Exchanging audio channels in MP3 files?

[Andrej Kluge]

Hi,

Is there a software that can exchange the audio channels (left/right) of
existing MP3 files, pereferably losslessly?

Reason: I have just ripped a large CD box to MP3, only to discover that the
channels are reversed. If I had known this before, I would have ripped them
to WAV, exchanged the channels and then converted them to MP3, but now this
would mean a lot of wasted time.

Of course I could just reverse the ear plugs of my headphones, but this is
no real solution...

Thanks and Ciao
AK

[Geoff]

Andrej Kluge wrote:
> Hi,
>
> Is there a software that can exchange the audio channels (left/right)
> of existing MP3 files, pereferably losslessly?
>
> Reason: I have just ripped a large CD box to MP3, only to discover
> that the channels are reversed. If I had known this before, I would
> have ripped them to WAV, exchanged the channels and then converted
> them to MP3, but now this would mean a lot of wasted time.
>
> Of course I could just reverse the ear plugs of my headphones, but
> this is no real solution...

This is presumable some file where sides really matter ? If not, just
imagine you are in the orchestra, band, or whatever, instead of in the
audience.

geoff

[GregS[_3_]]

In article >, "geoff" > wrote:
>Andrej Kluge wrote:
>> Hi,
>>
>> Is there a software that can exchange the audio channels (left/right)
>> of existing MP3 files, pereferably losslessly?
>>
>> Reason: I have just ripped a large CD box to MP3, only to discover
>> that the channels are reversed. If I had known this before, I would
>> have ripped them to WAV, exchanged the channels and then converted
>> them to MP3, but now this would mean a lot of wasted time.
>>
>> Of course I could just reverse the ear plugs of my headphones, but
>> this is no real solution...
>
>This is presumable some file where sides really matter ? If not, just
>imagine you are in the orchestra, band, or whatever, instead of in the
>audience.
>
>geoff


That reminds me of a club where there was a small bar in back of the band, up on a second balcony.
It was great to listen and practically be in the band, drummer 3 foot away. Definately
the best sound in the house, rather poor out front most of the time.

greg

[Andrej Kluge]

Hi,

geoff wrote:
>> Of course I could just reverse the ear plugs of my headphones, but
>> this is no real solution...
>
> This is presumable some file where sides really matter ?

Actually, yes. This is classical music, and if the violins play on the wrong
side it sounds definitely weird. Are there only pop/rock aficionados present
who don't understand this?

Ciao
AK

[Geoff]

Andrej Kluge wrote:
> Hi,
>
> geoff wrote:
>>> Of course I could just reverse the ear plugs of my headphones, but
>>> this is no real solution...
>>
>> This is presumable some file where sides really matter ?
>
> Actually, yes. This is classical music, and if the violins play on
> the wrong side it sounds definitely weird. Are there only pop/rock
> aficionados present who don't understand this?

Didn't you read my next sentence ;-)

But orchestral music on MP3 - surely you are joking ?

geoff

[Richard Crowley]

"Andrej Kluge" wrote ...
> Is there a software that can exchange the audio channels (left/right) of
> existing MP3 files, pereferably losslessly?
>
> Reason: I have just ripped a large CD box to MP3, only to discover that
> the
> channels are reversed. If I had known this before, I would have ripped
> them
> to WAV, exchanged the channels and then converted them to MP3, but now
> this
> would mean a lot of wasted time.

It seems highly doubtful that it can be done *losslessly*.
Because the data for the two channels is not independent
while encoded in stereo MP3 (as it would be in WAV,
for example.)

[David Nebenzahl]

On 1/21/2010 6:33 PM Richard Crowley spake thus:

> "Andrej Kluge" wrote ...
>
>> Is there a software that can exchange the audio channels
>> (left/right) of existing MP3 files, pereferably losslessly?
>>
>> Reason: I have just ripped a large CD box to MP3, only to discover
>> that the channels are reversed. If I had known this before, I would
>> have ripped them to WAV, exchanged the channels and then converted
>> them to MP3, but now this would mean a lot of wasted time.
>
> It seems highly doubtful that it can be done *losslessly*.
> Because the data for the two channels is not independent
> while encoded in stereo MP3 (as it would be in WAV,
> for example.)

So you're saying that MP3s are encoded using deltas *between* channels,
as well as within each channel? Never thought of it that way, but it
makes sense.

Still, would it really be any more lossy than doing any kind of editing
and re-saving on a MP3 file?


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"

[Andrej Kluge]

Hi,

Richard Crowley wrote:
>
> It seems highly doubtful that it can be done *losslessly*.
> Because the data for the two channels is not independent
> while encoded in stereo MP3 (as it would be in WAV,
> for example.)

Well I was hoping there would be only a bit or two to be changed in the MP3
header that control the channel assignement. (like those MP3 gain changing
programs where this is done without re-encoding the actual data)

If not, I will have to live with it.

Thanks for your reply,

Ciao
AK

[David Nebenzahl]

On 1/21/2010 11:19 PM Andrej Kluge spake thus:

> Richard Crowley wrote:
>
>> It seems highly doubtful that it can be done *losslessly*.
>> Because the data for the two channels is not independent
>> while encoded in stereo MP3 (as it would be in WAV,
>> for example.)
>
> Well I was hoping there would be only a bit or two to be changed in the MP3
> header that control the channel assignement. (like those MP3 gain changing
> programs where this is done without re-encoding the actual data)
>
> If not, I will have to live with it.

Or you could get a 4PDT switch and connect it between amp and speakers ...


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"

[Arny Krueger]

"David Nebenzahl" > wrote in message
.com
> On 1/21/2010 6:33 PM Richard Crowley spake thus:
>
>> "Andrej Kluge" wrote ...
>>
>>> Is there a software that can exchange the audio channels
>>> (left/right) of existing MP3 files, pereferably
>>> losslessly?

Not that I know of.

>>> Reason: I have just ripped a large CD box to MP3, only
>>> to discover that the channels are reversed. If I had
>>> known this before, I would have ripped them to WAV,
>>> exchanged the channels and then converted them to MP3,
>>> but now this would mean a lot of wasted time.

Not to mention potential quality loss. I don't know if channel rotation is
described in the file header or not.

>> It seems highly doubtful that it can be done
>> *losslessly*. Because the data for the two channels is
>> not independent while encoded in stereo MP3 (as it would
>> be in WAV, for example.)

Yes and no.

> So you're saying that MP3s are encoded using deltas
> *between* channels, as well as within each channel? Never
> thought of it that way, but it makes sense.

Both techniques are used. The sum/difference MP3s are called "Joint Stereo".

[Albie]

On Fri, 22 Jan 2010 07:44:36 -0500, "Arny Krueger" >
wrote:

>"David Nebenzahl" > wrote in message
.com
>> On 1/21/2010 6:33 PM Richard Crowley spake thus:
>>
>>> "Andrej Kluge" wrote ...
>>>
>>>> Is there a software that can exchange the audio channels
>>>> (left/right) of existing MP3 files, pereferably
>>>> losslessly?
>
>Not that I know of.
>
>>>> Reason: I have just ripped a large CD box to MP3, only
>>>> to discover that the channels are reversed. If I had
>>>> known this before, I would have ripped them to WAV,
>>>> exchanged the channels and then converted them to MP3,
>>>> but now this would mean a lot of wasted time.
>
>Not to mention potential quality loss. I don't know if channel rotation is
>described in the file header or not.
>
>>> It seems highly doubtful that it can be done
>>> *losslessly*. Because the data for the two channels is
>>> not independent while encoded in stereo MP3 (as it would
>>> be in WAV, for example.)
>
>Yes and no.
>
>> So you're saying that MP3s are encoded using deltas
>> *between* channels, as well as within each channel? Never
>> thought of it that way, but it makes sense.
>
>Both techniques are used. The sum/difference MP3s are called "Joint Stereo".
>


Why does one never seem to get a straight answer around here? 8-)

AFAICS, all you need do is to play your MP3 files back via software
that offers "Reverse" channels. You're on your own there, because I
still use WinAmp 2.8 (?), and this primitive does not offer that
feature. Most dedicated pre-amps _do_ have a channel reverse.

Failing this, you require a file editor that allows Copy/Paste, but
now you must reverse each of your files. I realize you want to avoid
doing this. (Sound Forge is good, but WaveOSaur is legitimately free!
8-) Its downside is, of course, a total lack of a manual.)

As to the wag who derides playing classical music with MP3 files, he
should avoid paper, pen and ink as they say. It is well-established
by now that the vast majority of mortals can discern no difference
when the sources have been well-recorded. When differences were
statistically proved, the few golden-eared listeners (like the VP of
A&R at DG) preferred the MP3 sound to the CD!! 8-) I understand that
many heavyweights in the field of psychology were involved when MP3
was developed and tested. It is nothing to deprecate.

Oh, and I can't remember who it was, but some world-class conductor
did place his violin section on the right. 8-) Try Googling for it.
I learned this from an ancient "Classic CD" magazine, (no longer in
print... like the rag reporting the famous MP3 lab test, supra).

Albie

[David Nebenzahl]

On 1/22/2010 6:47 AM Albie spake thus:

> As to the wag who derides playing classical music with MP3 files, he
> should avoid paper, pen and ink as they say. It is well-established
> by now that the vast majority of mortals can discern no difference
> when the sources have been well-recorded. When differences were
> statistically proved, the few golden-eared listeners (like the VP of
> A&R at DG) preferred the MP3 sound to the CD!! 8-) I understand that
> many heavyweights in the field of psychology were involved when MP3
> was developed and tested. It is nothing to deprecate.
>
> Oh, and I can't remember who it was, but some world-class conductor
> did place his violin section on the right. 8-) Try Googling for it.
> I learned this from an ancient "Classic CD" magazine, (no longer in
> print... like the rag reporting the famous MP3 lab test, supra).

Dunno about violins on the right (don't doubt it, just have never heard
of that), but I do know that George Szell (Cleveland Orch.) swapped the
violas and celli, putting the violas on the outside right. (There's a
picture showing this on the cover of an ablum I have of his.) No doubt
there have been other unconventional seating arrangements used over the
years.


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"

[cjt]

David Nebenzahl wrote:
> On 1/22/2010 6:47 AM Albie spake thus:
>
>> As to the wag who derides playing classical music with MP3 files, he
>> should avoid paper, pen and ink as they say. It is well-established
>> by now that the vast majority of mortals can discern no difference
>> when the sources have been well-recorded. When differences were
>> statistically proved, the few golden-eared listeners (like the VP of
>> A&R at DG) preferred the MP3 sound to the CD!! 8-) I understand that
>> many heavyweights in the field of psychology were involved when MP3
>> was developed and tested. It is nothing to deprecate.
>>
>> Oh, and I can't remember who it was, but some world-class conductor
>> did place his violin section on the right. 8-) Try Googling for it.
>> I learned this from an ancient "Classic CD" magazine, (no longer in
>> print... like the rag reporting the famous MP3 lab test, supra).
>
> Dunno about violins on the right (don't doubt it, just have never heard
> of that), but I do know that George Szell (Cleveland Orch.) swapped the
> violas and celli, putting the violas on the outside right. (There's a
> picture showing this on the cover of an ablum I have of his.) No doubt
> there have been other unconventional seating arrangements used over the
> years.
>
>
Nothing unconventional about that -- it's the difference between
"American" and "European" seating.

[Albie]

On Thu, 21 Jan 2010 19:06:07 +0100, "Andrej Kluge" >
wrote:

>Hi,
>
>Is there a software that can exchange the audio channels (left/right) of
>existing MP3 files, pereferably losslessly?
>
>Reason: I have just ripped a large CD box to MP3, only to discover that the
>channels are reversed. If I had known this before, I would have ripped them
>to WAV, exchanged the channels and then converted them to MP3, but now this
>would mean a lot of wasted time.
>
>Of course I could just reverse the ear plugs of my headphones, but this is
>no real solution...
>
>Thanks and Ciao
>AK


And I just have downloaded and used a program called "Audacity 1.2.6"
in the event you want to go the hard route. This editor would permit
of channel-swapping, inter alia, and the best part: It's Free!

Many tutorials available. Downloaded separately.

More of a heavyweight than WaveOSaur, but not quite as easy to use.

Albie

[Andrej Kluge]

Hi,

Albie wrote:
> And I just have downloaded and used a program called "Audacity
> 1.2.6" in the event you want to go the hard route. This editor
> would permit of channel-swapping, inter alia

On MP3 files? Without re-encoding?

(for WAV files, I already have one program which does that)

Ciao
AK

[Richard Crowley]

"Andrej Kluge" < wrote ...
> Albie wrote:
>> And I just have downloaded and used a program called "Audacity
>> 1.2.6" in the event you want to go the hard route. This editor
>> would permit of channel-swapping, inter alia
>
> On MP3 files? Without re-encoding?

No. Seems unlikely that there are ANY applications that can manipulate
MP3 without decoding and re-encoding. Same problem in the video
world with most flavors of MPEG.

[Albie]

On Sat, 23 Jan 2010 21:57:10 -0800, "Richard Crowley"
> wrote:

>"Andrej Kluge" < wrote ...
>> Albie wrote:
>>> And I just have downloaded and used a program called "Audacity
>>> 1.2.6" in the event you want to go the hard route. This editor
>>> would permit of channel-swapping, inter alia
>>
>> On MP3 files? Without re-encoding?
>
>No. Seems unlikely that there are ANY applications that can manipulate
>MP3 without decoding and re-encoding. Same problem in the video
>world with most flavors of MPEG.

Au contraire! I just did it. With Audacity, one loads an MP3 file,
edits same and then "Exports" it back to Either an MP3 file or a WAV
file! It probably does silently convert to RAW in order to edit, but
the user has no inkling of it.

You might prefer the truly intuitive use of WaveOSaur. It has a
primary flaw in that it only handle file sizes of around 32 megs.
To circumvent this, download another freebie called Slice Audio File
Splitter. It will permit inaudible splits such that WaveOSaur can
accomodate them. I have used this with great success.

THIS JUST IN! I see where WaveOSaur has a "Swap Channels" function. I
have not used it, but it appears as a MenuItem under the "Process"
Menu. HEY, FINALLY A DIRECT ANSWER TO A QUESTION !! 8-)

Albie

[David Nebenzahl]

On 1/24/2010 7:03 AM Albie spake thus:

> On Sat, 23 Jan 2010 21:57:10 -0800, "Richard Crowley"
> > wrote:
>
>> "Andrej Kluge" < wrote ...
>>
>>> Albie wrote:
>>>
>>>> And I just have downloaded and used a program called "Audacity
>>>> 1.2.6" in the event you want to go the hard route. This editor
>>>> would permit of channel-swapping, inter alia
>>>
>>> On MP3 files? Without re-encoding?
>>
>> No. Seems unlikely that there are ANY applications that can
>> manipulate MP3 without decoding and re-encoding. Same problem in
>> the video world with most flavors of MPEG.
>
> Au contraire! I just did it. With Audacity, one loads an MP3 file,
> edits same and then "Exports" it back to Either an MP3 file or a WAV
> file! It probably does silently convert to RAW in order to edit, but
> the user has no inkling of it.

I'm sure you did it, but this still raises the question: was your MP3
data degraded by the "silent" decoding and re-encoding that occurred
when you edited it? If so, it may not have been enough for you to have
realized that this happened.

I'm not asking this rhetorically; I actually don't know. I *suspect*
that what Mr. Crowley warned about is the case, that any application
that manipulates MP3s in any way must decode and re-encode them, which
by implication means that the data will be degraded each time, since
this is a lossy format. Is this correct?

If so, it's the same thing, by analogy, as making a xerox of a xerox of
a xerox of a xerox of a ...; each time through, the image gets a little
more degraded.

Now if only there was a bit somewhere in the MP3 header which said
"reverse channel assignments" ...


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"

[Andrej Kluge]

Hi,

David Nebenzahl wrote:
> I'm not asking this rhetorically; I actually don't know. I *suspect*
> that what Mr. Crowley warned about is the case, that any application
> that manipulates MP3s in any way must decode and re-encode them,
> which by implication means that the data will be degraded each
> time, since this is a lossy format. Is this correct?

AFAIK yes.

> Now if only there was a bit somewhere in the MP3 header which said
> "reverse channel assignments" ...

Exactly my notion.

I've got a promising reply from someone in the German audio newsgroup,
mentioning some internal technical specs and the need to do the programming
myself, but when there is such a possibilty I'm sure someone has implemented
it in some program somewhere.

Ciao
AK

[Richard Crowley]

"Albie" wrote ...
> "Richard Crowley" wrote:
>>"Andrej Kluge" < wrote ...
>>> Albie wrote:
>>>> And I just have downloaded and used a program called "Audacity
>>>> 1.2.6" in the event you want to go the hard route. This editor
>>>> would permit of channel-swapping, inter alia
>>>
>>> On MP3 files? Without re-encoding?
>>
>>No. Seems unlikely that there are ANY applications that can manipulate
>>MP3 without decoding and re-encoding. Same problem in the video
>>world with most flavors of MPEG.
>
> Au contraire! I just did it. With Audacity, one loads an MP3 file,
> edits same and then "Exports" it back to Either an MP3 file or a WAV
> file! It probably does silently convert to RAW in order to edit, but
> the user has no inkling of it.

NO, You DECODED the MP3 to WAV (or its internal equivalent) .
You may not have known that you did that because the application
did it automatically (and surreptitiously) behind the scenes. Then,
you re-encoded it back to MP3 (perhaps automatically without being
asked). But this is exactly what the OP was asking to NOT do.

[Andrej Kluge]

Hi,

Richard Crowley wrote:
>> Au contraire! I just did it. With Audacity, one loads an MP3
>> file, edits same and then "Exports" it back to Either an MP3 file
>> or a WAV file! It probably does silently convert to RAW in order
>> to edit, but the user has no inkling of it.
>
> NO, You DECODED the MP3 to WAV (or its internal equivalent) .
> You may not have known that you did that because the application
> did it automatically (and surreptitiously) behind the scenes. Then,
> you re-encoded it back to MP3 (perhaps automatically without being
> asked). But this is exactly what the OP was asking to NOT do.

Thanks, I thought I was talking to a brick wall :)

Ciao
AK

[David Nebenzahl]

On 1/24/2010 1:07 PM Andrej Kluge spake thus:

> David Nebenzahl wrote:
>
>> I'm not asking this rhetorically; I actually don't know. I *suspect*
>> that what Mr. Crowley warned about is the case, that any application
>> that manipulates MP3s in any way must decode and re-encode them,
>> which by implication means that the data will be degraded each
>> time, since this is a lossy format. Is this correct?
>
> AFAIK yes.
>
>> Now if only there was a bit somewhere in the MP3 header which said
>> "reverse channel assignments" ...
>
> Exactly my notion.
>
> I've got a promising reply from someone in the German audio newsgroup,
> mentioning some internal technical specs and the need to do the programming
> myself, but when there is such a possibilty I'm sure someone has implemented
> it in some program somewhere.

Well, it all depends on what's in the MP3 header, and from what I've
seen it doesn't look promising. Here's a page with a description of the
header:

http://www.mp3-converter.com/mp3codec/mp3_anatomy.htm

According to this, there are two fields having to do with the
channel-ness of the file:

o Channel mode (stereo, joint stereo, dual channel, single channel)
o Mode extension (used only with joint stereo, to conjoin channel data)

That second field looks intriguing, but I haven't been able to find any
sites which actually explain its function so far. Perhaps you can
determine this. But I don't think there's anything here that lets you
swap stereo channels, unfortunately.

If you could, it would be trivially easy to write a program which would
read an MP3, change some bits in the header and rewrite it. (The hardest
part would be if you had to recalculate a checksum because of the
changed data, but even this is a piece of cake.)


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"

[Albie]

On Sun, 24 Jan 2010 12:39:21 -0800, David Nebenzahl
> wrote:

>On 1/24/2010 7:03 AM Albie spake thus:
>
>> On Sat, 23 Jan 2010 21:57:10 -0800, "Richard Crowley"
>> > wrote:
>>
>>> "Andrej Kluge" < wrote ...
> >>
>>>> Albie wrote:
> >>>
>>>>> And I just have downloaded and used a program called "Audacity
>>>>> 1.2.6" in the event you want to go the hard route. This editor
>>>>> would permit of channel-swapping, inter alia
>>>>
>>>> On MP3 files? Without re-encoding?
>>>
>>> No. Seems unlikely that there are ANY applications that can
>>> manipulate MP3 without decoding and re-encoding. Same problem in
>>> the video world with most flavors of MPEG.
>>
>> Au contraire! I just did it. With Audacity, one loads an MP3 file,
>> edits same and then "Exports" it back to Either an MP3 file or a WAV
>> file! It probably does silently convert to RAW in order to edit, but
>> the user has no inkling of it.
>
>I'm sure you did it, but this still raises the question: was your MP3
>data degraded by the "silent" decoding and re-encoding that occurred
>when you edited it? If so, it may not have been enough for you to have
>realized that this happened.
>
>I'm not asking this rhetorically; I actually don't know. I *suspect*
>that what Mr. Crowley warned about is the case, that any application
>that manipulates MP3s in any way must decode and re-encode them, which
>by implication means that the data will be degraded each time, since
>this is a lossy format. Is this correct?
>
>If so, it's the same thing, by analogy, as making a xerox of a xerox of
>a xerox of a xerox of a ...; each time through, the image gets a little
>more degraded.
>
>Now if only there was a bit somewhere in the MP3 header which said
>"reverse channel assignments" ...

As to point one, it would depend upon the listener. What is audible
degradation to one guy might pass unnoticed to another. Our channel
switcher will just have to use the free software, switch a file and
give a listen. No need to A-B test. It is personal satisfaction
only.

As to point two, someone has pointed out that one channel is but the
delta of the other. If so, a single bit switched shouldn't work. The
best answer then lies in the analog world. Like in the days of the
cave man, his preamp needs a Reverse Channels knob. 8-)

Albie

[Geoff]

Albie wrote:
> As to the wag who derides playing classical music with MP3 files, he
> should avoid paper, pen and ink as they say. It is well-established
> by now that the vast majority of mortals can discern no difference
> when the sources have been well-recorded. When differences were
> statistically proved, the few golden-eared listeners (like the VP of
> A&R at DG) preferred the MP3 sound to the CD!! 8-) I understand that
> many heavyweights in the field of psychology were involved when MP3
> was developed and tested. It is nothing to deprecate.

Me. Anything with sensitive low-level harmonicly-rich sounds in conjunction
with louder components, and many other sceanrios, is likely to suffer
audibly and obviousy to all but the most cloth-eared. But if you are happy
with the quality yu achieve, go for it.

geoff

PS, Classical music typiaclly does not have violins with flangers.

[Geoff]

Richard Crowley wrote:
> "Andrej Kluge" < wrote ...
>> Albie wrote:
>>> And I just have downloaded and used a program called "Audacity
>>> 1.2.6" in the event you want to go the hard route. This editor
>>> would permit of channel-swapping, inter alia
>>
>> On MP3 files? Without re-encoding?
>
> No. Seems unlikely that there are ANY applications that can manipulate
> MP3 without decoding and re-encoding. Same problem in the video
> world with most flavors of MPEG.

Yeah - just because it doesn't explicitly say it's not re-encoding doesn't
mean that it isn't !

geof

[Mr.T]

"Albie" > wrote in message
...
> As to the wag who derides playing classical music with MP3 files, he
> should avoid paper, pen and ink as they say. It is well-established
> by now that the vast majority of mortals can discern no difference
> when the sources have been well-recorded. When differences were
> statistically proved, the few golden-eared listeners (like the VP of
> A&R at DG) preferred the MP3 sound to the CD!! 8-) I understand that
> many heavyweights in the field of psychology were involved when MP3
> was developed and tested. It is nothing to deprecate.

And anybody who claims they are unable to tell an MP3 from a wave file, and
still fails to make any mention of bit rates is just as stupid!

Fact is at 320kbs MP3's will suit most people and most music just fine. At
64kbs or less, MP3's with almost any encoder and almost any type of music is
pretty easy to pick for nearly everyone.
If *you* can't I wouldn't admit it to the world! :-)

MrT.

[Mr.T]

"David Nebenzahl" > wrote in message
.com...
> >>>> And I just have downloaded and used a program called "Audacity
> >>>> 1.2.6" in the event you want to go the hard route. This editor
> >>>> would permit of channel-swapping, inter alia
> >>>
> >>> On MP3 files? Without re-encoding?

If you only use it to PLAY the file and *NOT* resave it, then only one
decode to wave takes place, and no more loss than any other MP3 player
occurs.


> >> No. Seems unlikely that there are ANY applications that can
> >> manipulate MP3 without decoding and re-encoding. Same problem in
> >> the video world with most flavors of MPEG.
> >
> > Au contraire! I just did it. With Audacity, one loads an MP3 file,
> > edits same and then "Exports" it back to Either an MP3 file or a WAV
> > file! It probably does silently convert to RAW in order to edit, but
> > the user has no inkling of it.
>
> I'm sure you did it, but this still raises the question: was your MP3
> data degraded by the "silent" decoding and re-encoding that occurred
> when you edited it? If so, it may not have been enough for you to have
> realized that this happened.

Of *course* it adds loss when you decode AND re-encode! However what most
people don't realise is that the greatest loss occors on the first encode.
Once that part of the signal is gone, it doesn't have to be re-encoded next
time. From my experiments the first encode reduces quality by about the same
as the next 4 or 5 re-encodes. YMMV.


> Now if only there was a bit somewhere in the MP3 header which said
> "reverse channel assignments" ...

As others have pointed out, any player can do it easily after it has decoded
to wave. Not all MP3 players provide that facility of course, but it's
certainly not difficult to do.

MrT.

[Mr.T]

"Albie" > wrote in message
...
> As to point two, someone has pointed out that one channel is but the
> delta of the other.

For the joint stereo mode only.

>If so, a single bit switched shouldn't work.

Yes it would, all MP3 files are decoded to wave files when they are played.
The player can easily reassign which signal to output to each channel
*after* decoding takes place.
(not all players necessarily provide that facility of course, and there
appears to be no header bit to make it automatic, but it CAN certainly be
done!)


>The
> best answer then lies in the analog world. Like in the days of the
> cave man, his preamp needs a Reverse Channels knob. 8-)

Yep, or a reverse channel software switch to do the same thing.
If he has neither he could build a line switcher or speaker switcher, or
learn to live with it and worry about something important instead.

MrT.

[Andrej Kluge]

Hi,

Mr.T wrote:
> Fact is at 320kbs MP3's will suit most people and most music just
> fine. At 64kbs or less, MP3's with almost any encoder and almost any
> type of music is pretty easy to pick for nearly everyone.
> If *you* can't I wouldn't admit it to the world! :-)

My MP3s have 256 kb/s, and this is OK for me. My hearing is not what it used
to be anyway (the trebles are dwindling), so this is -- for me -- the best
tradeoff between quality and file size.

Ciao
AK

[Doug Freyburger]

Mr.T wrote:
>
> And anybody who claims they are unable to tell an MP3 from a wave file, and
> still fails to make any mention of bit rates is just as stupid!

That or they listen to their music in their car and the background noise
overwhelms any of that detail. Why do so few folks listen to classical
music in their car? You mean there were supposed to be violins going
while that truck went by? I think the "wall of sound" concept was
introduced to rock music because so many folks were listening to the
music on their car radios so the music needed to overwhelm that truck
going by.

Side by side in an otherwise silent room, sure I can tell an MP3 from a
wave file. Ah to even have a room where I could do that on a regular
basis ...

[David Nebenzahl]

On 1/25/2010 11:09 PM Mr.T spake thus:

> "David Nebenzahl" > wrote in message
> .com...
>
>> I'm sure you did it, but this still raises the question: was your MP3
>> data degraded by the "silent" decoding and re-encoding that occurred
>> when you edited it? If so, it may not have been enough for you to have
>> realized that this happened.
>
> Of *course* it adds loss when you decode AND re-encode! However what most
> people don't realise is that the greatest loss occors on the first encode.
> Once that part of the signal is gone, it doesn't have to be re-encoded next
> time. From my experiments the first encode reduces quality by about the same
> as the next 4 or 5 re-encodes. YMMV.

I didn't know this, though it makes perfect sense now that I think of it.

It would be nice to know how this works quantitatively, based on
empirical evidence. Not doubting you, just wondering how much loss
occurs right off the bat. If the 2nd decode-encode cycle adds negligible
loss, then it might be OK to edit the file to reverse the channels.


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"

[Dave Platt]

In article >,
David Nebenzahl > wrote:

>If you could, it would be trivially easy to write a program which would
>read an MP3, change some bits in the header and rewrite it. (The hardest
>part would be if you had to recalculate a checksum because of the
>changed data, but even this is a piece of cake.)

Based on what I know/read of MPEG audio encoding, I think that the
problem you're trying to solve *is* solvable, but is rather more
complex than you would wish.

In order to swap channels in an MP3 stream, you'd need to do something
along the following lines:

- Separate the stream into frames, by detecting the frame syncs and
parsing the headers.

- Un-do the Huffman coding (a lossless operation) to recover the
frame full of perceptually-coded data (this is a lossless operation)

- Based on the information in the mode and mode extension fields,
"tear apart" the encoded (quantized) data for the left and right
channels, and then "put it back together" in the opposite
orientation. In the case of a joint-stereo encoding I imagine that
this might require swapping the sign of the inter-channel
difference value. I *think* that this swapping-around could be
done losslessly (without decoding and then re-encoding), at least
in most cases, but I can't swear to that.

- Do a new pass of Huffman encoding (which is lossless) and put the
frame headers onto each Huffman block (this might require changing
the padding bits).

- Stream out the frames.

--
Dave Platt > AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

[Geoff]

Doug Freyburger wrote:
> Mr.T wrote:
>>
>> And anybody who claims they are unable to tell an MP3 from a wave
>> file, and still fails to make any mention of bit rates is just as
>> stupid!
>
> That or they listen to their music in their car and the background
> noise overwhelms any of that detail. Why do so few folks listen to
> classical music in their car? You mean there were supposed to be
> violins going while that truck went by? I think the "wall of sound"
> concept was introduced to rock music because so many folks were
> listening to the music on their car radios so the music needed to
> overwhelm that truck going by.
>
> Side by side in an otherwise silent room, sure I can tell an MP3 from
> a wave file. Ah to even have a room where I could do that on a
> regular basis ...

I use 256K (non-joint) stereo MP3s in my car on long trips. I can hear the
difference easily between these and the source CDs, in the car, while
driving, and that with average pop-rock, let alone anything more subtle.

I put up with it for the convenience. In the car. Only.


geoff

[Mr.T]

"David Nebenzahl" > wrote in message
s.com...
> It would be nice to know how this works quantitatively, based on
> empirical evidence. Not doubting you, just wondering how much loss
> occurs right off the bat. If the 2nd decode-encode cycle adds negligible
> loss, then it might be OK to edit the file to reverse the channels.

Simply do what I did and try it for yourself.
You won't get any "empirical evidence" here for *your* music with *your*
encoder, and *your* settings.

MrT.

[David Nebenzahl]

On 1/26/2010 8:34 PM Mr.T spake thus:

> "David Nebenzahl" > wrote in message
> s.com...
>
>> It would be nice to know how this works quantitatively, based on
>> empirical evidence. Not doubting you, just wondering how much loss
>> occurs right off the bat. If the 2nd decode-encode cycle adds negligible
>> loss, then it might be OK to edit the file to reverse the channels.
>
> Simply do what I did and try it for yourself.
> You won't get any "empirical evidence" here for *your* music with *your*
> encoder, and *your* settings.

No, by empirical evidence I meant some numeric value of comparison. Say,
maybe, number of samples changed between original and re-encoded stream,
or some such, as a rough measure of corruption. Of course any other
comparisons are going to be subjective. (And of course the measure of
corruption would depend on the specific source material; what I'd be
after would be an average over many samples.)


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"

[Mr.T]

"David Nebenzahl" > wrote in message
s.com...
> No, by empirical evidence I meant some numeric value of comparison. Say,
> maybe, number of samples changed between original and re-encoded stream,
> or some such, as a rough measure of corruption.

You could have 100% of samples changed without audible corruption, (or 1
sample changed can be audible) so I can't see what you expect that to tell
you?

>Of course any other comparisons are going to be subjective.

It's ALL subjective when you are dealing with lossy compression.

MrT.

[David Nebenzahl]

On 1/26/2010 9:14 PM Mr.T spake thus:

> "David Nebenzahl" > wrote in message
> s.com...
>
>> No, by empirical evidence I meant some numeric value of comparison. Say,
>> maybe, number of samples changed between original and re-encoded stream,
>> or some such, as a rough measure of corruption.
>
> You could have 100% of samples changed without audible corruption, (or 1
> sample changed can be audible) so I can't see what you expect that to tell
> you?

Well, that's true; just counting changed samples won't tell you
anything. But I'm sure there must be some way to quantify the level of
corruption, or more properly the degree of difference between a
re-encoded file and the original, based on what would actually be
audible rather than just raw numeric differences between samples. It
wouldn't be trivial to calculate, that's for sure.

Anyhow, at this point this is just an academic question and we've moved
way beyond the OP's issue.


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"

[Peter Larsen[_3_]]

Andrej Kluge wrote:

> Hi,

> geoff wrote:
>>> Of course I could just reverse the ear plugs of my headphones, but
>>> this is no real solution...

>> This is presumable some file where sides really matter ?

> Actually, yes. This is classical music, and if the violins play on
> the wrong side it sounds definitely weird. Are there only pop/rock
> aficionados present who don't understand this?

There is no reason why absolute L and R should not also matter in other
renderings of real or imaginary acoustic events.

> Ciao
> AK

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

Richard Crowley wrote:

> It seems highly doubtful that it can be done *losslessly*.
> Because the data for the two channels is not independent
> while encoded in stereo MP3 (as it would be in WAV,
> for example.)

Depends on the mp3 options selected, however the general rule _is_ that
decode-encode would be required.

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

David Nebenzahl wrote:

> So you're saying that MP3s are encoded using deltas *between*
> channels, as well as within each channel? Never thought of it that
> way, but it makes sense.

No no no, M-S encoding is one of the options, strict X-Y encoding of high
range (discarding ramdom phase between channels) another, that one kills
real ambience.

> Still, would it really be any more lossy than doing any kind of
> editing and re-saving on a MP3 file?

I wouldn't worry too much on the second encode if say max quality variable
bandwidth ms-encode was the initial choice. It is also possible to select
encode as fully independent channels, but that is an unlikely initial
choice.

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

Albie wrote:

> Why does one never seem to get a straight answer around here? 8-)

We do not *do* simple around here, it is against the union contract.

> AFAICS, all you need do is to play your MP3 files back via software
> that offers "Reverse" channels. You're on your own there, because I
> still use WinAmp 2.8 (?), and this primitive does not offer that
> feature. Most dedicated pre-amps _do_ have a channel reverse.

It is still a "must remember" thing, what is asked about is a "get it right"
thing.

> Failing this, you require a file editor that allows Copy/Paste, but
> now you must reverse each of your files.

No, no no and no. You only do that for a spoiler that allows you to identify
what work P.D.Q. Bach has pdq'ed.

> I realize you want to avoid
> doing this. (Sound Forge is good, but WaveOSaur is legitimately free!
> 8-) Its downside is, of course, a total lack of a manual.)

Reverse is a simple word with a clear meaning, since you ask for simplicity
and clarity please ponder at least 3/8's of a millisecond on what it
actually means.

> As to the wag who derides playing classical music with MP3 files, he
> should avoid paper, pen and ink as they say. It is well-established
> by now that the vast majority of mortals can discern no difference
> when the sources have been well-recorded.

First the took the psychoacoustics and based encode-decode schemes on them,
next those schemes had to be modified based on listening tests. My current
level of outdated information is that the books have not yet been rewritten.
I have also seen politically correct AES papers that - imo correctly - put
the major part of the difference between 96 k sample rate recordings and 48
k sample rate recordings in the category "those that use it also care more
about sound quality".

> When differences were
> statistically proved, the few golden-eared listeners (like the VP of
> A&R at DG) preferred the MP3 sound to the CD!! 8-)

What makes you assume that said VP has hearing that is perfect, even if only
by ENT standards that require only that he understands spoken word. There is
one special case where mp3 encoding can be helpful, one and only one. That
case is distortion or artifacts from digital noise reduction, such small and
audibly very bothering noises will be discarded in mp3 encoding.

> I understand that
> many heavyweights in the field of psychology were involved when MP3
> was developed and tested. It is nothing to deprecate.

Read the latter part of the above paragraph and the stuff about the
non-rewritten books on psychoacoustics again. The real rorschach test of mp3
is whether a Strad sounds like one afterwards, and it doesn't, it sounds
like a Yamaha.

> Oh, and I can't remember who it was, but some world-class conductor
> did place his violin section on the right. 8-)

I you may be writing about the alternative viennese orchestra setup. My
recollection is that it is not used as much because the standard setup makes
it easist for all the musicians to keep the pitch, it may be imperfect.

> Albie

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

David Nebenzahl wrote:

> Dunno about violins on the right (don't doubt it, just have never
> heard of that), but I do know that George Szell (Cleveland Orch.)
> swapped the violas and celli, putting the violas on the outside
> right. (There's a picture showing this on the cover of an ablum I
> have of his.) No doubt there have been other unconventional seating
> arrangements used over the years.

Doing that has some merit because it makes them more well defined by being
closer to the audience, but it has the disadvantage that the instrument
radiates away from the audience rather than towards it. In a string quartet
it is the setup I prefer from a recording viewpoint tho' ... violas can get
lost between 2' and cello otherwise, and the cello as the third from the
left as seen from the audience will also project more in the direction of
the audience than it will in position 4 and thus it is better able to
compensat for being in the 2' tier. In full ensemble as well as in chamber
ensemble context it primarily must be about required communication in the
ensemble, so for the same ensemble it could be work, ie. performed oeuvre,
dependent.

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

Albie wrote:

>>> On MP3 files? Without re-encoding?

>> No. Seems unlikely that there are ANY applications that can
>> manipulate MP3 without decoding and re-encoding. Same problem in
>> the video world with most flavors of MPEG.

> Au contraire! I just did it. With Audacity, one loads an MP3 file,
> edits same and then "Exports" it back to Either an MP3 file or a WAV
> file! It probably does silently convert to RAW in order to edit, but
> the user has no inkling of it.

I trust you about the magnitude of inkling, but you yourself describe a
decode-encode.

> THIS JUST IN! I see where WaveOSaur has a "Swap Channels" function. I
> have not used it, but it appears as a MenuItem under the "Process"
> Menu. HEY, FINALLY A DIRECT ANSWER TO A QUESTION !! 8-)

No Albie, the OP wants it right for all files he downloads to his preferred
earbuster.

> Albie

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

Andrej Kluge wrote:

> My MP3s have 256 kb/s, and this is OK for me. My hearing is not what
> it used to be anyway (the trebles are dwindling), so this is -- for
> me -- the best tradeoff between quality and file size.

It is not about treble, it is about detail, except that treble can get
splatty at low bit rates. Some of the time I downsample to 32 kHz samplerate
prior to encoding when using max quality variable bit rate ... anyway: mp3
sounds like the lack of detail just after a major noise exposure .... that
lack of detail applies 20-whatever it allows, the mptreble over 14 kHz kinda
sounds like white noise anyway .... I seriously think that not bothering the
encode with it is better than having it splattified.

> Ciao
> AK

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

Doug Freyburger wrote:

> Side by side in an otherwise silent room, sure I can tell an MP3 from
> a wave file. Ah to even have a room where I could do that on a
> regular basis ...

Better check with Arny's ABX software, it is good for the modesty, not all
nuances are best detected in short abx listening sessions, but it does put
things in a good order of importance.

Kind regards

Peter Larsen

[David Nebenzahl]

On 1/27/2010 12:08 AM Peter Larsen spake thus:

> Andrej Kluge wrote:
>
>> geoff wrote:
>>
>>>> Of course I could just reverse the ear plugs of my headphones, but
>>>> this is no real solution...
>
>>> This is presumable some file where sides really matter ?
>
>> Actually, yes. This is classical music, and if the violins play on
>> the wrong side it sounds definitely weird. Are there only pop/rock
>> aficionados present who don't understand this?
>
> There is no reason why absolute L and R should not also matter in other
> renderings of real or imaginary acoustic events.

I dunno; take a listen to the opening track of Jimi Hendrix's "Axis:
Bold as Love". Does it really matter if the whooshy sounds pan from
right to left to right, or vice versa?


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"

[Andrej Kluge]

Hi,

Peter Larsen wrote:
> No Albie, the OP wants it right for all files he downloads to his
> preferred earbuster.

Um, actually no. As I wrote I want it only for this special case -- a CD box
which I ripped from CD (not downloaded) and which has the audio channels
reversed (maybe it was done intentionally?).

Ok, I confess: while it is indeed classical music, it is no orchestral
music, but solo harpsichord. The trebles are on the left and the bass is on
the right, i.e. like you would hear it if you stand on the other side of the
harpsichord, facing the pianist (as opposed to what the pianist himself
would hear). That was a very strange experience. But I tell you what:
meanwhile (I'm about halfway through listening to it now) I got accustomed
to it :-)

Ciao
AK

[Peter Larsen[_3_]]

David Nebenzahl wrote:

> On 1/27/2010 12:08 AM Peter Larsen spake thus:

>> Andrej Kluge wrote:

>>> geoff wrote:

>>>>> Of course I could just reverse the ear plugs of my headphones, but
>>>>> this is no real solution...

>>>> This is presumable some file where sides really matter ?

>>> Actually, yes. This is classical music, and if the violins play on
>>> the wrong side it sounds definitely weird. Are there only pop/rock
>>> aficionados present who don't understand this?

>> There is no reason why absolute L and R should not also matter in
>> other renderings of real or imaginary acoustic events.

> I dunno; take a listen to the opening track of Jimi Hendrix's "Axis:
> Bold as Love". Does it really matter if the whooshy sounds pan from
> right to left to right, or vice versa?

How about a drumkit eh? - nothing said about the w i d t h of said.

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

Andrej Kluge wrote:

> Hi,

> Peter Larsen wrote:
>> No Albie, the OP wants it right for all files he downloads to his
>> preferred earbuster.

> Um, actually no. As I wrote I want it only for this special case -- a
> CD box which I ripped from CD (not downloaded) and which has the
> audio channels reversed (maybe it was done intentionally?).

> Ok, I confess: while it is indeed classical music, it is no orchestral
> music, but solo harpsichord. The trebles are on the left and the bass
> is on the right, i.e. like you would hear it if you stand on the
> other side of the harpsichord, facing the pianist (as opposed to what
> the pianist himself would hear). That was a very strange experience.
> But I tell you what: meanwhile (I'm about halfway through listening
> to it now) I got accustomed to it :-)

I record from the audience's perspective. Generally that would imply
recording any "piano class" object at least partly from the side it opens
the lid towards since that side would normally be the one the audience
hears.

> Ciao
> AK

Kind regards

Peter Larsen

[Doug Freyburger]

geoff wrote:
> Doug Freyburger wrote:
>> Mr.T wrote:
>
>>> And anybody who claims they are unable to tell an MP3 from a wave
>>> file, and still fails to make any mention of bit rates is just as
>>> stupid!
>
>> That or they listen to their music in their car and the background
>> noise overwhelms any of that detail. Why do so few folks listen to
>> classical music in their car? You mean there were supposed to be
>> violins going while that truck went by? I think the "wall of sound"
>> concept was introduced to rock music because so many folks were
>> listening to the music on their car radios so the music needed to
>> overwhelm that truck going by.
>
> I use 256K (non-joint) stereo MP3s in my car on long trips. I can hear the
> difference easily between these and the source CDs, in the car, while
> driving, and that with average pop-rock, let alone anything more subtle.

Clearly your hearing works differently than mine. I've seen people
moving their lips in very loud environments like rock concerts. Clearly
they believe the person they are facing will be able to hear them and
therefore they think they could hear the person facing them. Not me.
High enough background noise overwhlems the sound for me and turns it
off. If I'm in a car on the interstate and I go by a big truck it
doesn't matter in the least what sort of sound is theoretically coming
out of the speakers. It's enough Db under the level of the truck so
it's turned off for me.

I do wish there was such a thing as a test that measures hearing loss in
a way that has meaning in industrialized society. I get that playing a
quiet sound in a silent room does have some use. I've tried playing
those ring tones that kids use that adults can't here and I can only
hear the sound 5-10 years younger than the table predicts. But high
pitch pure tones aren't of much use when I'm at the airport and a jet
passes overhead. Or walking past a construction site with a jack
hammer. Or at a rock concert watching someone's lips move and figuring
they believe I should be able to hear something.

[Andrej Kluge]

Hi,

Dick Pierce wrote:
> Andrej Kluge wrote:
>>
>> Ok, I confess: while it is indeed classical music, it is no
>> orchestral music, but solo harpsichord. The trebles are on the
>> left and the bass is on the right, i.e. like you would hear it if
>> you stand on the other side of the harpsichord, facing the pianist
>> (as opposed to what the pianist himself would hear).
>
> One minor nit to start: pianists play, as a general rule,
> pianos, not harpsichords. Harpsichordists, cembalists or
> clavicinists play harpischords.

I knew someone would notice that slip :-) (the word escaped me when I wrote
this)

> Be that as it may, I have several harpsichords here.

You lucky dog.

> The radiation pattern of such intruments is EXCEEDINGLY
> complex and variable. Where, in fact, the major portion of
> a given note is radiated from the soundboard is not at all
> well correlated with the position of the key that sounded
> that not. And further, which portion of the note (spectrally)
> is radiated form where is as well VERY complex.

Well, I know how a grand piano looks inside, and that the strings here are
crossed so the direction where the sound comes from is indeed not easy to
discern. However, from what I've seen of cembalo (harpsichords) pictures
their strings are straight, i.e. the long (bass) strings are on the left
(seen from the player).

> Your stated phenomenon of a clear left-right auditory sense
> of where a note is oming from is exceedingly difficult to
> detect when you are sitting at the keyboard playing and make
> the concious effort to isolate what your hands are doing and,
> positionally, what your ears are hearing.

I just listened to other cembalo recordings of my collection (with
headphones or course) and noticed that in most of them (except the one in
question, and one other recording) both bass and treble comes (more or less)
from the center. The other recording with rather clear left/right separation
of bass/treble has the bass on the left and treble on right.

> For the audience, such a clear left-right distinction is
> simply absent auditorially, even from someone sitting 10
> feet from the instrument.

Yes, of course.

> All that being said, the vast majority of harpsichord
> recordings that exhibit a distinct bass-to-left, treble-
> to-right image do so unnaturally, some to the point of
> sounding just plain wierd.

Well, I wondered myself how these CDs have been recorded. Presumably with
two microphones hung directly into the instrument? The cembalo here is very
closely recorded, with practically no reverb (I like that since it brings
out contrapuntal structures very clearly). BTW, it's the 10 CD box with
Händel's complete harpsichord music played by Eberhard Kraus.

> But, if you want weird, I suppose you get to demand
> the proper wierd.

Sorry, I don't understand that (which may be because I'm German)

Thanks and Ciao
AK

[David Nebenzahl]

On 1/27/2010 7:55 AM Peter Larsen spake thus:

> David Nebenzahl wrote:
>
>> On 1/27/2010 12:08 AM Peter Larsen spake thus:
>>
>>> Andrej Kluge wrote:
>>>
>>>> geoff wrote:
>>>>
>>>>>> Of course I could just reverse the ear plugs of my headphones, but
>>>>>> this is no real solution...
>>>>>
>>>>> This is presumable some file where sides really matter ?
>>>>
>>>> Actually, yes. This is classical music, and if the violins play on
>>>> the wrong side it sounds definitely weird. Are there only pop/rock
>>>> aficionados present who don't understand this?
>>>
>>> There is no reason why absolute L and R should not also matter in
>>> other renderings of real or imaginary acoustic events.
>>
>> I dunno; take a listen to the opening track of Jimi Hendrix's "Axis:
>> Bold as Love". Does it really matter if the whooshy sounds pan from
>> right to left to right, or vice versa?
>
> How about a drumkit eh? - nothing said about the w i d t h of said.

Huh? What on earth does that have to do with channel assignment.

Sometimes you're just *out there*, man.


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"

[Geoff]

Andrej Kluge wrote:
> Hi,
>
> Peter Larsen wrote:
>> No Albie, the OP wants it right for all files he downloads to his
>> preferred earbuster.
>
> Um, actually no. As I wrote I want it only for this special case -- a
> CD box which I ripped from CD (not downloaded) and which has the
> audio channels reversed (maybe it was done intentionally?).
>
> Ok, I confess: while it is indeed classical music, it is no orchestral
> music, but solo harpsichord. The trebles are on the left and the bass
> is on the right, i.e. like you would hear it if you stand on the
> other side of the harpsichord, facing the pianist (as opposed to what
> the pianist himself would hear). That was a very strange experience.
> But I tell you what: meanwhile (I'm about halfway through listening
> to it now) I got accustomed to it :-)

Kind of depends if the player is facing you, back to you, or as would be
more usual - side on.


geoff

[Andrej Kluge]

Hi,

Dick Pierce wrote:
> The stound of a harpsichord or piano does not come from
> the strings, it comes from the soundboard. The strings
> have far too small a radiating area and acoustically couple
> very inefficiently. Rather, the vibration of the strings
> is coupled mechanically through the bridge pines through
> the bridge to the soundboard and thence mechanically to
> the portion(s) of the soundboard that's best at radiating
> that particular frequency when excited from that particular
> point in the bridge.

Interesting, I didn't know that. One of my friends has a spinet in his
basement. Next time I see him I have to have a closer look.

> In all of the times I have played and listened live to harpsichord
> performance on may dozens of different instruments ranging from
> real historical samples to modern reproducrtions, I can't say
> that I have ever heard the clear left/right distinction you
> observe in your recordings.

I could send you a sample if you want. In one piece there is a scale right
at the beginning, you can clearly hear how it goes from right to left.

Ciao
AK

[Andrej Kluge]

Hi,

Dick Pierce wrote:
> Thanks for the offer but, no thanks. I would consider such
> a presentation to be strange and, unless the recording was
> the only one around for the piece or the performance was
> exemplary, I'd not be interested.

Well, I think many pieces of that CD box are the only recordings you will
find of them. And yes, IMO the performance is outstanding, YMMV.

But you can hear a sample here:

http://www.jpc.de/jpcng/classic/detail/-/art/Georg-Friedrich-H%E4ndel-Das-Gesamtwerk-f%FCr-Cembalo-Vol-9/hnum/7600128

Track 27 (Menuet h-Moll) will show the left/right issue quite well.

Or:
http://www.jpc.de/jpcng/classic/detail/-/art/Georg-Friedrich-H%E4ndel-Das-Gesamtwerk-f%FCr-Cembalo-Vol-6/hnum/7600094

Track 6 (Fantasia a-Moll)

Ciao
AK

[David Nebenzahl]

On 1/27/2010 1:39 PM Andrej Kluge spake thus:

> Dick Pierce wrote:
>
>> The stound of a harpsichord or piano does not come from
>> the strings, it comes from the soundboard. The strings
>> have far too small a radiating area and acoustically couple
>> very inefficiently. Rather, the vibration of the strings
>> is coupled mechanically through the bridge pines through
>> the bridge to the soundboard and thence mechanically to
>> the portion(s) of the soundboard that's best at radiating
>> that particular frequency when excited from that particular
>> point in the bridge.
>
> Interesting, I didn't know that. One of my friends has a spinet in his
> basement. Next time I see him I have to have a closer look.

That's true for *all* stringed instruments (well, all "acoustic" ones at
any rate). A vibrating string by itself can produce almost no audible
sound. It needs some kind of diaphragm to move air.

And to further complicate matters, it's not just the soundboard of the
instrument that radiates sound. Depending on the instrument, other parts
also participate: for instance, the back in both the guitar and violin
family of instruments contributes significantly to the sound.

And directionality is yet another more complex subject. At least with a
violin (and undoubtedly other instruments as well), the perceived
direction of sound--as well as the perceived direction depending on
frequency--is not always the obvious one. There seems to be a certain
amount of acoustic black magic at work betwixt sound source and listener.


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"

[Andrej Kluge]

Hi,

David Nebenzahl wrote:
> On 1/27/2010 1:39 PM Andrej Kluge spake thus:
>
>> Dick Pierce wrote:
>>
>>> The stound of a harpsichord or piano does not come from
>>> the strings, it comes from the soundboard.
>>
>> Interesting, I didn't know that. One of my friends has a spinet in
>> his basement. Next time I see him I have to have a closer look.
>
> That's true for *all* stringed instruments (well, all "acoustic"
> ones at any rate). A vibrating string by itself can produce almost
> no audible sound. It needs some kind of diaphragm to move air.

I admid that I looked up "soundboard" in the dictionary only after I wrote
my posting (in German: "Korpus", "Klangkörper"). I thought it is some
special device in harpsichords, but of course every string instrument has
it.

> And directionality is yet another more complex subject. At least
> with a violin (and undoubtedly other instruments as well), the
> perceived direction of sound--as well as the perceived direction
> depending on frequency--is not always the obvious one.

Yet in the recordings I mentioned the direction of the notes can be clearly
heard.

Thanks and Ciao
AK

[Geoff]

Andrej Kluge wrote:
> Hi,
>
> David Nebenzahl wrote:
>> On 1/27/2010 1:39 PM Andrej Kluge spake thus:
>>
>>> Dick Pierce wrote:
>>>
>>>> The stound of a harpsichord or piano does not come from
>>>> the strings, it comes from the soundboard.
>>>
>>> Interesting, I didn't know that. One of my friends has a spinet in
>>> his basement. Next time I see him I have to have a closer look.
>>
>> That's true for *all* stringed instruments (well, all "acoustic"
>> ones at any rate). A vibrating string by itself can produce almost
>> no audible sound. It needs some kind of diaphragm to move air.
>
> I admid that I looked up "soundboard" in the dictionary only after I
> wrote my posting (in German: "Korpus", "Klangkörper"). I thought it
> is some special device in harpsichords, but of course every string
> instrument has it.
>
>> And directionality is yet another more complex subject. At least
>> with a violin (and undoubtedly other instruments as well), the
>> perceived direction of sound--as well as the perceived direction
>> depending on frequency--is not always the obvious one.
>
> Yet in the recordings I mentioned the direction of the notes can be
> clearly heard.
>
> Thanks and Ciao
> AK

[Geoff]

Andrej Kluge wrote:

> Yet in the recordings I mentioned the direction of the notes can be
> clearly heard.

And from a rasonably 'audience' listening position ?

geoff

[Peter Larsen[_3_]]

David Nebenzahl wrote:

>>> I dunno; take a listen to the opening track of Jimi Hendrix's "Axis:
>>> Bold as Love". Does it really matter if the whooshy sounds pan from
>>> right to left to right, or vice versa?

>> How about a drumkit eh? - nothing said about the w i d t h of said.

> Huh? What on earth does that have to do with channel assignment.

I didn't say anyting about the width because it doesn't have anything to do
with channel assignment.

> Sometimes you're just *out there*, man.

There is a standard setup of a drumkit, so there is a proper way to render
it in stereo, just as there is a proper way to render a piano or a string
quartet.

Kind regards

Peter Larsen

[Mr.T]

"Andrej Kluge" > wrote in message
...
> Well, I think many pieces of that CD box are the only recordings you will
> find of them. And yes, IMO the performance is outstanding, YMMV.

Seems to me they have probably just panned it that way deliberately, and
simply converting it to mono may be an improvement. That will provide better
quality MP3's at any given bit rate as a bonus.

MrT.

[Mr.T]

"Andrej Kluge" > wrote in message
...
> Yet in the recordings I mentioned the direction of the notes can be
clearly
> heard.

But may have been deliberately panned with frequency dependant channel
splitting, at the whim of the producer.
Frankly I'd just convert it to mono!

MrT.

[Andrej Kluge]

Hi,

Mr.T wrote:
>> Yet in the recordings I mentioned the direction of the notes can
>> be clearly heard.
>
> But may have been deliberately panned with frequency dependant
> channel splitting, at the whim of the producer.

Somehow I don't think so, as the recordings are from 1972. Did such
knowledge/technology exist back then?

> Frankly I'd just convert it to mono!

No, this doesn't sound good with headphones (IMO.

Ciao
AK

[Andrej Kluge]

Hi,

Andrej Kluge wrote:
> Yet in the recordings I mentioned the direction of the notes can be
> clearly heard.

By the way, in those two samples I mentioned, the cembalo in use was a
Grimaldi. I found pictures of those on the web:

http://www.de.early-keyboard.com/Grimaldi.htm

They seem rather long (compared to other cembali) -- I suspect the sound
engineer had put one microphone at the far left side and the other on the
far right side of it, and thus created this spacial distinction?

Ciao
AK

[Mr.T]

"Andrej Kluge" > wrote in message
...
> > But may have been deliberately panned with frequency dependant
> > channel splitting, at the whim of the producer.
>
> Somehow I don't think so, as the recordings are from 1972. Did such
> knowledge/technology exist back then?

Of course, you just use a couple of mics (or even send the same signal to
two mixer channels), EQ, and pan as desired. Simple.


> > Frankly I'd just convert it to mono!
>
> No, this doesn't sound good with headphones (IMO.


Hell if you are using headphones, simply swap them to the other ears! How
hard is that?
Either way it's still going to sound wrong of course.

MrT.

[David Nebenzahl]

On 1/29/2010 5:17 AM Dick Pierce spake thus:

> These instruments are very typical of 17th and 18th century
> Italian harpsichords. and they are actually somewhat smaller
> in overall size compared to other regional variants. If you
> were to look, for example, at some of the early- to mid-18th
> century German harpsichords, which are, as harpsichord go,
> almost gargantuan, things like the Grimaldi would look tiny
> by comparison.

Being a harpsichord person, you might appreciate this story. (Then
again, you might not.)

In another lifetime, I used to play in orchestras. One time we were
doing some Baroque violin concerto or other (Bach or some such), with a
harpsichord next to the conductor's podium. I remember during the dress
rehearsal, the solo violinist went over to the harpsichord to give the
orchestra an A. He hit the key and had an annoyed look on his face. He
then proceeded to hit the key several times more, each time with more
force and a more annoyed look.

We thought it was pretty funny.


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"

[John[_48_]]

Winamp allows you to swap Left/Right channels when you play (using
plugins):

Options > Preferences
- Plug-ins - DSP/Effect
Select "Nullsoft Signal Processing Studio DSP"
Click "Configure active plug-in"
Click "Load" button
Load "justin - stereo channel swap.sps"

There is also a separate stereo swapper plugin.

Hope that helps,
John
http://www.mp3-boss.com

[Bohgosity BumaskiL]

"Andrej Kluge" > wrote in message
...
> Hi,
>
> Richard Crowley wrote:
>>
>> It seems highly doubtful that it can be done *losslessly*.
>> Because the data for the two channels is not independent
>> while encoded in stereo MP3 (as it would be in WAV,
>> for example.)
>
> Well I was hoping there would be only a bit or two to be changed in the
> MP3
> header that control the channel assignement. (like those MP3 gain changing
> programs where this is done without re-encoding the actual data)
>
> If not, I will have to live with it.

You can look up the format in wikipedia, and more details are in technical
documents. I think such an operation is do-it-yourself. Maybe there is an
*MP3 mod utility* (lossless MP3 modification utility). Some such thing is
for JPEGs. I am lost at how you managed to exchange stereo channels
unintentionally. This is coming from a guy who has sixteen presets on my
stereo processor in Nero WaveEdit. If you actually prefer violins on one
side or the other, then it might do you some good to lose that polarity. I
will always do my duet vocals cross-channel from my synth, now that I am
routinely including synth.
_______
http://ecn.ab.ca/~brewhaha/Sound/Sucker.mp3
If it sounds too good to be true, then don't be a sucker.