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  #1   Report Post  
Doc
 
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Default Someone says "anything over -10db in digital video is distortion" and you say....

Someone made the statement that "on a digital video deck you want to keep
the levels below -10db because above that you're into distortion." Further
they state that 0db is the same as clipping. I was under the impression that
attempting to *exceed* 0db yields clipping, since there isn't anything over
0db. Soundforge definitely makes a distinction between 0db and "clipped".

What say any of you?

Thanks for all shared wisdom.



  #2   Report Post  
Martin Heffels
 
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On Tue, 21 Jun 2005 21:00:43 GMT, "Doc"
wrote:

Someone made the statement that "on a digital video deck you want to keep
the levels below -10db because above that you're into distortion."


I think this person is mixing-up two things. Yes, you keep your levels
below -10dB in the digital domain, and you do this in order to avoid
them reaching 0dB, because that is where they clip. The area between
-10dB and 0dB is what is called "the headroom", and is there for
louder sounds (plosives, cough, whatever).
-10dB is quite high actually, if you don't know exactly what you're
doing. You can pick your choice between -12dB, -14dB, -18dB and even
-20dB. All these values are used as safeguard against clipping, and
each soundo has his own standard. I use generally -12dB for normal
dialogue, and -18dB if I don't know what could happen. But you will
have to find your own comfort-zone, because mine does not need to be
yours

cheers

-martin-

--
"Now I want you to say it thrice daily and don't dress a bun"
  #3   Report Post  
Steve King
 
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"Doc" wrote in message
nk.net...
Someone made the statement that "on a digital video deck you want to keep
the levels below -10db because above that you're into distortion."
Further
they state that 0db is the same as clipping. I was under the impression
that
attempting to *exceed* 0db yields clipping, since there isn't anything
over
0db. Soundforge definitely makes a distinction between 0db and "clipped".

What say any of you?

Thanks for all shared wisdom.


You are correct. I think the intent may have been to say that metering,
being what it is, an average of -10 (or -8 or -18 or ??) is a good place to
place the average peaks, because there will often be peaks that exceed the
average by 10 db or so. Therefore, to avoid clipping set a level that will
acommodate all peaks so that none exceeds the brick wall 0 dbfs.

Steve King


  #4   Report Post  
Mark
 
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Martin Heffels wrote:
On Tue, 21 Jun 2005 21:00:43 GMT, "Doc"
wrote:

Someone made the statement that "on a digital video deck you want to keep
the levels below -10db because above that you're into distortion."


I think this person is mixing-up two things. Yes, you keep your levels
below -10dB in the digital domain, and you do this in order to avoid
them reaching 0dB, because that is where they clip. The area between
-10dB and 0dB is what is called "the headroom", and is there for
louder sounds (plosives, cough, whatever).
-10dB is quite high actually, if you don't know exactly what you're
doing. You can pick your choice between -12dB, -14dB, -18dB and even
-20dB. All these values are used as safeguard against clipping, and
each soundo has his own standard. I use generally -12dB for normal
dialogue, and -18dB if I don't know what could happen. But you will
have to find your own comfort-zone, because mine does not need to be
yours

cheers

-martin-


And also the short plosives or other short transient sounds may not
register fully on the meter or led's so they may be well over 0 dB but
don't register over 0 dB.

I actually thik people should pay more attention to the AVERAGE meter
reading rather that the peak. Pick a level say -15 dB and try to set
the level so that 1/2 the time the meter is above -15 and 1/2 the time
it is below. If you do it this way, the "loudness" i.e how loud it
actually sounds ... will be more consistent.

Mark


Mark

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Jonny Durango
 
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Doc wrote:
Someone made the statement that "on a digital video deck you want to keep
the levels below -10db because above that you're into distortion." Further
they state that 0db is the same as clipping. I was under the impression that
attempting to *exceed* 0db yields clipping, since there isn't anything over
0db. Soundforge definitely makes a distinction between 0db and "clipped".

What say any of you?

Thanks for all shared wisdom.




This person is mixing levels....-10dB is a line level voltage for
certain equipment, not a reference point for where clipping begins. 0dB
is the absolute ceiling of the loudest volume that can be recorded on
digital equipment (ie. 16 1 bits for that sample). It's possible for a
-15dBu signal to cause clipping on some equipment, and a +5dB u signal
to be below clipping on other equipment.

Many people and software will consider the point at which you reach, but
not exceed 0dBFS to be clipping, simply because they are both
represented the same way in binary (all 1's)

Other people, like myself, believe that clipping may occur, but only
matters when you can hear it. Some equipment handles clipping really
well, and if you're recording a thrash distorted guitar part you might
not even notice lots of clipping. On the other hand, if you're recording
clean vocals, you probably won't be fine with even minimal clipping.

But yes I think you're right, clipping occurs when they are no more
zeros to turn on to represent the extra signal, or there are no more
metal oxide particles in a tape to represent the xtra signal/information.

Jonny Durango


  #6   Report Post  
Arny Krueger
 
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Doc wrote:

Someone made the statement that "on a digital video deck

you want to
keep the levels below -10db because above that you're into
distortion."


Most digital equipment clips someplace in the last 1 dB
before FS. Up until that point, digital equipment is
generally very clean.

However this begs the question - how are you measuring
levels? There's really only one totally reliable way to
measure levels in the digital domain, and that is to record
a sample and then look at it with a DAW.

What you actually record is where the rubber hits the road.
Everything else is an estimate.

Further they state that 0db is the same as clipping.


In many cases, clipping of real world digital equipment
takes place a bit below 0 dB, IOW -0.1 dB or maybe even as
low as -0.5 dB.

Furthermore, clipping might be frequency-dependent. If
clipping is frequency-dependent, the clip point is probably
the lowest at the highest frequencies. Most equipment will
hit its highest undistorted levels at 10 KHz, but there may
be increasing losses at higher frequencies.

Most of my cautionary comments apply to the less expensive
digital equipment.

I was under the impression that attempting to *exceed*

0db yields
clipping, since there isn't anything over 0db.


Fact is, a lot of digital equipment clips at some point
above -1 dB, but below 0 dB.

Soundforge definitely
makes a distinction between 0db and "clipped".


Theoretically, 0 dB signals are not clipped.



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Captain Slick
 
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Jonny Durango wrote:



But yes I think you're right, clipping occurs when they are no more
zeros to turn on to represent the extra signal, or there are no more
metal oxide particles in a tape to represent the xtra signal/information.

Jonny Durango


You'd hear the clipping at playback with D/A conversion, correct?

Then wouldn't it depend on the converter? If the converter created a
smooth peak (possible?) would that explain why some equipment handles it
better?
--


- Bill
  #8   Report Post  
Doc
 
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"Doc" wrote in message
nk.net...
Someone made the statement that "on a digital video deck you want to keep
the levels below -10db because above that you're into distortion."

Further
they state that 0db is the same as clipping. I was under the impression

that
attempting to *exceed* 0db yields clipping, since there isn't anything

over
0db. Soundforge definitely makes a distinction between 0db and "clipped".


I think I should clarify, this is referring to material that's already been
recorded, not a question of where to set the levels during recording.

I was under the impression that the waveform and VU meter in Soundforge etc.
"shows all". That there are no peaks that don't show up on the wave form and
the VU meter tells you exactly what the peak levels are up to 0db, unlike
analog meters which show an approximation of the peaks, which are likely
somewhat below the actual levels.

Yes? No?


  #9   Report Post  
DanR
 
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Doc wrote:
Someone made the statement that "on a digital video deck you want to keep
the levels below -10db because above that you're into distortion." Further
they state that 0db is the same as clipping. I was under the impression that
attempting to *exceed* 0db yields clipping, since there isn't anything over
0db. Soundforge definitely makes a distinction between 0db and "clipped".

What say any of you?

Thanks for all shared wisdom.


In an environment with digital and analog VTRs "tone" always is set to read 0 on
an analog VU meter and -20 on a digital meter. I am referring mainly to Beta SP
(analog) and Digi-Beta (digital machines) With properly recorded audio the level
on a Beta SP deck will fluctuate around the 0 level marker but sometimes read a
couple of db over. The same audio will read maybe 10 db above the -20 marker on
the digital machines due to it's "peak reading" tendencies.
In the old days (with tape) when there were only VU meters an engineer had to
"just know" that certain sounds would read much lower on a VU meter than they
really were. An extreme example would be orchestra bells or a triangle. If you
let the level approach -10 on a VU meter the sound would be distorted. This was
especially important on the first generation of the recording. Some of the
extreme peaks would saturate the tape but in a gentle way. Later in the "mix"
you could boost these same sounds and avoid the distortion because the extreme
peaks in the overtones were now gone.


  #10   Report Post  
William Sommerwerck
 
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Assuming the meter shows the true instantaneous peak level, this is utter
crap.

On a digital recorder, the higher the recording level the _lower_ the
distortion -- until you exceed 0dB, at which point you clip.




  #11   Report Post  
Doc
 
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"Arny Krueger" wrote in message
...
Doc wrote:


However this begs the question - how are you measuring
levels? There's really only one totally reliable way to
measure levels in the digital domain, and that is to record
a sample and then look at it with a DAW.


Soundforge.

In case you haven't seen my previous posts I'll give you a quick rundown.
Made a Firewire transfer of a musical performance from a DVCam deck to my
Sony TRV-240 Digital8 camcorder. From there through a Firewire port to my
H/D. When looking at the still unprocessed file I found that the highest
peaks were either right at 0db or registered as clipped. All the highest
peaks were in one particular song which was somewhat higher in level than
the rest of the performance.

I should probably mention that the people who recorded the sound at the
performance really messed up all over the place - they showed up late and
didn't get to do a sound check. Her vocal levels were all over the place in
the mix from hot and distorted to buried. Half the time she couldn't hear
herself in the monitors. Her mic died during one song. During the opening
bars of the performance (for TV), someone apparently hit the "on" button on
the onboard reverb - suddenly the sound is awash in ridiculously overboard
reverb and a couple of seconds later it suddenly goes away (I can just see
the board guy fumbling in a panicked scramble for the fader or pot.) It was
apparent from the shape of the waveform that for some reason the first and
last songs had compression/limiting applied to them - with a lot of
accompanying distortion - I assume with an onboard compressor/limiter they
had. Why just the first and last songs I have no idea. Given everything else
that happened, I have to wonder if they even knew they were doing it. Can't
imagine why the TV studio would do it.

Anyway, the fact is there's distortion all over the place, even in places
where the sound is nowhere near clipping. It's not caused by my gear, the
VHS copy the station gave her of the original tape sounds the same way.

I used Soundforge to add reverb via the Acoustic Mirror plugin. To do this,
I had to lower the overall levels by 2db to keep many more peaks from
clipping than already were once the reverb was applied. I figured I should
put it back to where it was, i.e. with the highest peaks (maybe 2 or 3
spikes where this ocurred) at 0db, which is what I did. Saved the whole
thing with the DV format, played it back to my camcorder via firewire and
then back to their DVcam deck.

When I mentioned to the Station manager about the levels issue, he seemed
incredulous that any of them were that hot. I explained that this is where
they were on the original file. He even asked if I had "adjusted" anything
during the Firewire transfer. I'm not aware that this is even possible. I
was under the impression that a Firewire transfer is utterly unlike going
from an analog source, that a transfer simply dumps whatever data is on the
digital tape to the h/d, no user intervention possible. At any rate, all I
did was set up the cam, hook up the Firewire cable and hit "capture" on the
Pinnacle Studio 9 software.


  #12   Report Post  
Mike Rivers
 
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Default


In article et writes:

Someone made the statement that "on a digital video deck you want to keep
the levels below -10db because above that you're into distortion."


That would be a pretty bad digital video deck, however they may want
to keep the peaks 10 dB below full scale because they want to have
10 dB of headroom in their playback chain. It could be that the deck
that they play back from produces an analog output from a -10 dBFS
digital recording that drives their system into clipping, but that's
sloppy system engineering on their part.

In any case, it's convention, and a trade organization (SMPTE)
standard, to deliver recordings that don't peak above -10 dBFS.

Further
they state that 0db is the same as clipping.


That's not correct.

First off, 'dB' by itself doesn't mean anything when talking about
levels. Let's assume that we're talking about dB relative to digital
full scale, which is the maximum digital level. This is what 0 dBFS
is, and it's likely that this is what your misinformant meant by "0
dB." You can have a recording with peaks that reach 0 dBFS that isn't
clipped. And you can't exceed 0 dBFS. But if you put an analog signal
into an A/D converter high enough so that it would go over 0 dBFS if
it could, then you'll get clipping.

Soundforge definitely makes a distinction between 0db and "clipped".


Most digital devices have a "clip" indicator, but those work in
different ways. (there's no standard for it) Some will light up when
the level gets to within a couple of tenths of a dB of full scale (say
-0.2 dBFS) just to give you warning that you're about to clip if
things get much louder. Some light up as soon as it sees a sample that
reaches full scale (this is becoming common for 24-bit systems).
Others light up when they see three (or some other number greater than
one) consecutive samples at the full scale value. That's a pretty good
guess that clipping has occurred, but if you're recording square
waves, you can have the clip light on all day and still be recording
what you put in.



--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo
  #14   Report Post  
Arny Krueger
 
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Doc wrote:


When I mentioned to the Station manager about the levels

issue, he
seemed incredulous that any of them were that hot. I

explained that
this is where they were on the original file. He even

asked if I had
"adjusted" anything during the Firewire transfer.


What's to adjust? ;-)

I'm not aware that
this is even possible. I was under the impression that a

Firewire
transfer is utterly unlike going from an analog source,

that a
transfer simply dumps whatever data is on the digital tape

to the
h/d, no user intervention possible.


That's my experience.

At any rate, all I did was set up
the cam, hook up the Firewire cable and hit "capture" on

the Pinnacle
Studio 9 software.


I've done my camcorder transfers using real basic software
and hardware - namely Windows Movie Maker (WMM) and a
generic Firewire card. It seems to work like clock - I push
some buttons, wait for a while and there's an AVI file on my
hard drive.

If I need to play with the sound track more seriously than
what WMM allows, I've used Audition/CE to pull the sound
track off of the computer file that Windows Movie Maker
created. WMM supports adding a stereo audio track back into
the movie from my hard drive.

Since the audio is always kept in the digital domain,
there's really not a lot to mess it up. It is what it is,
until I start playing with it with one of the editors that I
use.


  #15   Report Post  
Martin Heffels
 
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On Tue, 21 Jun 2005 23:11:40 GMT, "Doc"
wrote:

I'm not aware that this is even possible. I
was under the impression that a Firewire transfer is utterly unlike going
from an analog source, that a transfer simply dumps whatever data is on the
digital tape to the h/d, no user intervention possible.


You are right.

-m-

--
"Now I want you to say it thrice daily and don't dress a bun"


  #16   Report Post  
GKB
 
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I haven't read all the posts , but -10 digital seems to becoming a new
T.V. standard ,
From feeding cameras to the quality control inspector at discovery channel
sending shows back if there are peaks over that !

Maybe Will , will lend his experience , but it seems to combatting sloppy
field
work and over agressive transmitter chains .

regards Greg



"Doc" wrote in message
nk.net...
Someone made the statement that "on a digital video deck you want to keep
the levels below -10db because above that you're into distortion."

Further
they state that 0db is the same as clipping. I was under the impression

that
attempting to *exceed* 0db yields clipping, since there isn't anything

over
0db. Soundforge definitely makes a distinction between 0db and "clipped".

What say any of you?

Thanks for all shared wisdom.





  #17   Report Post  
Mike Rivers
 
Posts: n/a
Default


In article t writes:

Made a Firewire transfer of a musical performance from a DVCam deck to my
Sony TRV-240 Digital8 camcorder. From there through a Firewire port to my
H/D. When looking at the still unprocessed file I found that the highest
peaks were either right at 0db or registered as clipped.


That seems like it was a pretty hot recording. There was nothing in
your transfer process that would have added gain, so it is what it is.
If you were to play back the audio from the analog outputs of your
camcorder, you probably would have heard the clipping.

Unless one of the transfer options that you used automatically
normalized the recording on the way in. If peaks were formerly at
-10 dBFS, normalization would have brough the loudest peak up to
0 dBFS, but still not clipped digitally. You might want to take
another look at the settings in your transfer process. There might be
a button on there that you don't realize is pressed.

I should probably mention that the people who recorded the sound at the
performance really messed up all over the place - they showed up late and
didn't get to do a sound check. Her vocal levels were all over the place in
the mix from hot and distorted to buried.


Anyway, the fact is there's distortion all over the place, even in places
where the sound is nowhere near clipping.


That could explain the clipping on the recording. But depending on the
analog chain feeding the original recorder, it could have been clipped
going into the recorder. The digital level might have been OK, but
they were recording a clipped signal, perhaps at the mic input stage.

When I mentioned to the Station manager about the levels issue, he seemed
incredulous that any of them were that hot. I explained that this is where
they were on the original file. He even asked if I had "adjusted" anything
during the Firewire transfer. I'm not aware that this is even possible.


I've seen the "normalize on import" option on something that I have
around here. I don't have Sound Forge so I know that's not where I saw
it, but I know that it's an option on something. Maybe it's on
Tracktion. It's not a program that I use often enough to remember, and
it's not an option that I'd want to use.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo
  #18   Report Post  
Steve Guidry
 
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FWIW, we set reference tone at -10 on the DV deck's meters when recording
dialog. For music, we usually use -12. But on dialog, we're nearly always
compressed at least 3:1 at the mixer, so the 10 is more like 30.

And for music, there's just too much the audio guy does to the 2-mix to
fully explain here, but for levels, there's usually a compressor on most
every input (some of them 2-stage). For critical events, there's a separate
multi-track recording for re-mix, etc.

Steve



"Steve King" wrote in message
...
"Doc" wrote in message
nk.net...
Someone made the statement that "on a digital video deck you want to

keep
the levels below -10db because above that you're into distortion."
Further
they state that 0db is the same as clipping. I was under the impression
that
attempting to *exceed* 0db yields clipping, since there isn't anything
over
0db. Soundforge definitely makes a distinction between 0db and

"clipped".

What say any of you?

Thanks for all shared wisdom.


You are correct. I think the intent may have been to say that metering,
being what it is, an average of -10 (or -8 or -18 or ??) is a good place

to
place the average peaks, because there will often be peaks that exceed the
average by 10 db or so. Therefore, to avoid clipping set a level that

will
acommodate all peaks so that none exceeds the brick wall 0 dbfs.

Steve King




  #19   Report Post  
Steve Roberts
 
Posts: n/a
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On Tue, 21 Jun 2005 23:16:48 +0200, Martin Heffels
wrote:

On Tue, 21 Jun 2005 21:00:43 GMT, "Doc"
wrote:

Someone made the statement that "on a digital video deck you want to keep
the levels below -10db because above that you're into distortion."


I think this person is mixing-up two things. Yes, you keep your levels
below -10dB in the digital domain, and you do this in order to avoid
them reaching 0dB, because that is where they clip. The area between
-10dB and 0dB is what is called "the headroom", and is there for
louder sounds (plosives, cough, whatever).
-10dB is quite high actually, if you don't know exactly what you're
doing. You can pick your choice between -12dB, -14dB, -18dB and even
-20dB. All these values are used as safeguard against clipping, and
each soundo has his own standard. I use generally -12dB for normal
dialogue, and -18dB if I don't know what could happen. But you will
have to find your own comfort-zone, because mine does not need to be
yours


Over here in the BBC, we use -18dbfs as our reference level and we set
our peak to 8db higher than that - ie -10dbfs. This ensure that
there's always 10db of headroom before the onset of clipping.

Steve

The Doctor Who Restoration Team Website
http://www.restoration-team.co.uk
  #20   Report Post  
 
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The general standard for video in the US is (and has been for quite
some time) peaks at -10 and vu levels peaking between -18 and -24.
While this standard does fail to take advantage of the additional 10db
of headroom available in the digital realm, it allows for a seamless
signal flow between analog and digital machines.
This is not the case with DVDs, where there is not yet a clear standard
established.



  #22   Report Post  
Lorin David Schultz
 
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"Doc" wrote:

Someone made the statement that "on a digital video deck you want
to keep the levels below -10db because above that you're into
distortion."




They *might* have meant that it causes distortion further down the
chain. Or maybe they're just unclear on the details.

Either way, the standard in digital video these days is 0VU = -20dBFS
with peaks not exceeding -10dBFS. Some facilities nudge the 0VU mark up
or down a bit, but the -10dBFS ceiling seems pretty consistent.

--
"It CAN'T be too loud... some of the red lights aren't even on yet!"
- Lorin David Schultz
in the control room
making even bad news sound good

(Remove spamblock to reply)


  #23   Report Post  
Steve King
 
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"Lorin David Schultz" wrote in message
news:rGyve.60173$wr.18573@clgrps12...
"Doc" wrote:

Someone made the statement that "on a digital video deck you want
to keep the levels below -10db because above that you're into
distortion."




They *might* have meant that it causes distortion further down the chain.
Or maybe they're just unclear on the details.

Either way, the standard in digital video these days is 0VU = -20dBFS with
peaks not exceeding -10dBFS. Some facilities nudge the 0VU mark up or
down a bit, but the -10dBFS ceiling seems pretty consistent.


Of course, haven't we all seen the postings about Sony PD150/170 cameras and
their prosumer equivilents VX2000/2001 that will deliver excessively noisy
results at those settings? It is my understanding that other manufacturers
of this category of camera suffer similarly. Shortly after I switched from
BetaSP to DVCAM I had to reschedule an interview that was recorded to the
standards suggested by Lorin on a PD150. The result was simply too noisy to
use. It was an honest mistake by an experienced sound professional who
tried to apply standards that worked with analogue BetaSP to a new digital
format that simply doesn't have the capability to accommodate 20 dB of
headroom. (As a side note, the second interview was a bust. The
spontanaity of the first sitting was gone. Caution replaced candor. It
will, unfortunately, not be used in the documentary that is still an ongoing
project.)

Steve King


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Mike Rivers
 
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In article writes:

Of course, haven't we all seen the postings about Sony PD150/170 cameras and
their prosumer equivilents VX2000/2001 that will deliver excessively noisy
results at those settings?


Not me, but then I don't travel in those circles.

It is my understanding that other manufacturers
of this category of camera suffer similarly. Shortly after I switched from
BetaSP to DVCAM I had to reschedule an interview that was recorded to the
standards suggested by Lorin on a PD150. The result was simply too noisy to
use. It was an honest mistake by an experienced sound professional who
tried to apply standards that worked with analogue BetaSP to a new digital
format that simply doesn't have the capability to accommodate 20 dB of
headroom.


According to the classic definition, no digital system has any
headroom. When you get to 0 dBFS, you have no place else to go. You
make your own amount of headroom based on your familiarity (or
unfamiliarity) with the program material, and adherence to the
client's wishes. At -20 dBFS, in even the crummiest of the crummy, you
should have at least 60 dB of dynamic range available. Are you
suggesting that you barely have 20 dB of dynamic range below -20 dBFS?
That's absurd.

Maybe someone told him "record beween -10 and -20" and he was watching
the VU meter on his mixer barely move off the downscale pin. That, of
course, won't word, since 0 VU is calibrated to some nominal level
which is probably in the ballpark of the nominal recording level,
analog or digital (unless there's a +4/-10 discrepancy that nobody
accounted for).


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo
  #25   Report Post  
Steve King
 
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"Mike Rivers" wrote in message
news:znr1119798122k@trad...

In article
writes:

Of course, haven't we all seen the postings about Sony PD150/170 cameras
and
their prosumer equivilents VX2000/2001 that will deliver excessively
noisy
results at those settings?


Not me, but then I don't travel in those circles.


I'm not sure what you mean by this, but the topic of audio problems with the
PD150 and VX2000 have been discussed on this newsgroup as well as more
extensively on RAMPS. I'll include a quote from Jay Rose about the PD150:

"Sony started with the inferior preamp/AD in their VX2000, and added
balancing and phantom. Period. When the world complained about the awful
s/n, they (AFAIK) added a
software-based noise gate. No per-unit cost, those clever guys... If you
do a traditional measurement with an input signal that goes away -- what
Sound Devices did -- the gate kicks in and s/n is apparently improved.
It's simply a single-band masking phenomenon... the noise is still there,
and apparent with some signals."

It is my understanding that other manufacturers
of this category of camera suffer similarly. Shortly after I switched
from
BetaSP to DVCAM I had to reschedule an interview that was recorded to the
standards suggested by Lorin on a PD150. The result was simply too noisy
to
use. It was an honest mistake by an experienced sound professional who
tried to apply standards that worked with analogue BetaSP to a new
digital
format that simply doesn't have the capability to accommodate 20 dB of
headroom.


According to the classic definition, no digital system has any
headroom.


I was speaking of the 20 dB between -20 dBfs and digital full scale, but
thanks for the lecture anyway.

When you get to 0 dBFS, you have no place else to go. You
make your own amount of headroom based on your familiarity (or
unfamiliarity) with the program material, and adherence to the
client's wishes. At -20 dBFS, in even the crummiest of the crummy, you
should have at least 60 dB of dynamic range available. Are you
suggesting that you barely have 20 dB of dynamic range below -20 dBFS?
That's absurd.


What I tried to say, perhaps not well, is that if the tone is set at -20dBfs
and program peaks are allowed to go no higher than -16 dBfs on a PD150 with
the internal limiters off, audio recorded in a quiet setting will have an
objectionable amount of pre-amp noise. I am simply relating my experience
in hundreds of hours of shooting with PD150s and VX2000s and making my
evaluations based on 40 years of broadcast, recording studio, and video
production experience. But, I'm still learning every day ;-)

Maybe someone told him "record beween -10 and -20" and he was watching
the VU meter on his mixer barely move off the downscale pin. That, of
course, won't word, since 0 VU is calibrated to some nominal level
which is probably in the ballpark of the nominal recording level,
analog or digital (unless there's a +4/-10 discrepancy that nobody
accounted for).


Unfortunately, I was the director, so if there was any telling going on it
was me doing it. It was a very early shoot with the PD150 and the first
interior in a quiet office. Previous locations had been in exterior
locations, where ambient noise masked the camera audio deficiencies.

All that said, when one knows the inherent problems of the Sony cameras,
they can deliver excellent picture results and satisfactory audio tracks. I
have since adopted a working method for run and gun using a microphone (or
wireless receiver) directly into the camera of leaving the internal limiters
on and adjusting levels to peak around -6 dbfs. The internal limiters are
not great, but they do prevent clipping. This seems to be an acceptable
compromise. When feeding the cameras from an external mixer better results
can be had by turning off the internal camera limiters and using the mixer
limiters to keep audio from exceeding digital full scale yet still peak
around the -6 dBfs point.

Steve King

I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo





  #26   Report Post  
Mike Rivers
 
Posts: n/a
Default


In article writes:

Not me, but then I don't travel in those circles.


I'm not sure what you mean by this, but the topic of audio problems with the
PD150 and VX2000 have been discussed on this newsgroup as well as more
extensively on RAMPS. I'll include a quote from Jay Rose about the PD150:


Geez, I haven't seen a post here from Jay Rose in years. Hey, Jay!
Howzitgon'?

Perhaps I should clarify "those circles." If people are discussing a
problem with a video recorder, I usually can't really be of any help
and it's not something I'm likely to need to know, so to avoid
overcrowding my brain, I might not be paying much attention to such
discussions.

What I tried to say, perhaps not well, is that if the tone is set at -20dBfs
and program peaks are allowed to go no higher than -16 dBfs on a PD150 with
the internal limiters off, audio recorded in a quiet setting will have an
objectionable amount of pre-amp noise.


Well, that's (as Jay said) because they use crappy preamps. It's not a
fault of the medium or method. I wouldn't tolerate a piece of
equipment that poor. You just can't work with it. If it has that poor
a noise floor, I'd suspect that it probably also starts to distort, or
maybe even clips, when you put enough level into it to reach full
scale. But since I don't have one, I can't confirm any of this.

All that said, when one knows the inherent problems of the Sony cameras,
they can deliver excellent picture results and satisfactory audio tracks. I
have since adopted a working method for run and gun using a microphone (or
wireless receiver) directly into the camera of leaving the internal limiters
on and adjusting levels to peak around -6 dbfs. The internal limiters are
not great, but they do prevent clipping. This seems to be an acceptable
compromise.


Whatever works. If it's an otherwise good setup, you do what you have
to do. Maybe the next generation will be better.

--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo
  #28   Report Post  
Alex Bird
 
Posts: n/a
Default



Mike Rivers wrote:
In article writes:

Of course, haven't we all seen the postings about Sony PD150/170 cameras and
their prosumer equivilents VX2000/2001 that will deliver excessively noisy
results at those settings?


Not me, but then I don't travel in those circles.

It is my understanding that other manufacturers
of this category of camera suffer similarly. Shortly after I switched from
BetaSP to DVCAM I had to reschedule an interview that was recorded to the
standards suggested by Lorin on a PD150. The result was simply too noisy to
use. It was an honest mistake by an experienced sound professional who
tried to apply standards that worked with analogue BetaSP to a new digital
format that simply doesn't have the capability to accommodate 20 dB of
headroom.


According to the classic definition, no digital system has any
headroom. When you get to 0 dBFS, you have no place else to go. You
make your own amount of headroom based on your familiarity (or
unfamiliarity) with the program material, and adherence to the
client's wishes. At -20 dBFS, in even the crummiest of the crummy, you
should have at least 60 dB of dynamic range available. Are you
suggesting that you barely have 20 dB of dynamic range below -20 dBFS?
That's absurd.

Maybe someone told him "record beween -10 and -20" and he was watching
the VU meter on his mixer barely move off the downscale pin. That, of
course, won't word, since 0 VU is calibrated to some nominal level
which is probably in the ballpark of the nominal recording level,
analog or digital (unless there's a +4/-10 discrepancy that nobody
accounted for).


I find this hard to believe too. On the other hand I've heard some
rough sound from one of these cameras recording an interview. I think
they were using 32kHz sampling through ignorance, I don't think the
levels were too bad, but the amount of mushy noise from the lossy
compression was unimpressive.

Alex

  #29   Report Post  
Richard Crowley
 
Posts: n/a
Default


"Doc" wrote in message
nk.net...
Someone made the statement that "on a digital video deck you want to
keep
the levels below -10db because above that you're into distortion."


Sounds like they were refering to some sort of local "stanndard"
for keeping the average at -10dBFS to allow 10dB of hedroom.

10dB seems pretty risky unless you have a very predictable
source. Most of us use -20dBFS as the reference (it would
have been called the 0dB point back in analog days.)

Further they state that 0db is the same as clipping. I was under
the impression that attempting to *exceed* 0db yields clipping,
since there isn't anything over 0db.


In the real world the difference between 0dB and OVER 0dB
is nonexistent. Nobody can adjust levels to keep the signal peaks
at 0 without going over. Some compressors can come very
close, but you don't want to hear what happens to your audio
when you push it that close.

Soundforge definitely makes a distinction between 0db and "clipped".


Soundforge is working on after-the-fact files, not real-time
recording level setting.

  #30   Report Post  
 
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I use Dorrough 280-D meters, which display vu and peak levels
simultaneously. Since -20 on the digital scale = 0 vu, vu levels
peaking between -18 and -24 on the digital scale = +2 to -4 in the
analog realm, so long as machines are calibrated to -20. Sorry this
wasn't clear in my last post.

Mike Rivers wrote:
In article .com writes:

The general standard for video in the US is (and has been for quite
some time) peaks at -10 and vu levels peaking between -18 and -24.


That's true for digital peak levels, which are not indicated by a VU
meter. Do you know where the -18 to -24 range on the VU scale is?
Let's not get our meters confused.




  #31   Report Post  
Martin Heffels
 
Posts: n/a
Default

On Sun, 26 Jun 2005 14:09:27 GMT, "Lorin David Schultz"
wrote:

Either way, the standard in digital video these days is 0VU = -20dBFS
with peaks not exceeding -10dBFS.


Avid seems to think 0VU=-14dBFS.
I know I am whinging here, but your standard does not have to be my
standard. If you want to speak about such a standard, it is wise to
add in which country you are, so people can apply your suggestions
to their situations.

cheers

-martin-

--
"Now I want you to say it thrice daily and don't dress a bun"
  #35   Report Post  
 
Posts: n/a
Default

I'm with ya Mike. In addition to the Dorroughs, I have an old pair of
analog vu meters I keep an eye on as well when setting levels.



  #36   Report Post  
 
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On 2005-06-27
said:
writes: I use Dorrough 280-D meters, which
display vu and peak levels simultaneously. Since -20 on the
digital scale = 0 vu, vu levels peaking between -18 and -24 on
the digital scale = +2 to -4 in the analog realm, so long as
machines are calibrated to -20. Sorry this wasn't clear in my

last post. That's a good meter and it tells you a lot. Being an old
fuddyduddy myself, I still use an analog console with pretty close
to real VU meters on it. I find that with my digital stuff
calibrated so that 0 VU equals -20 dBFS, by watching the VU meters
the way I always have, I get perfectly satisfactory record levels.

Ditto here. I have a vu indicator which gives me an audible tone at
0vu and set things up with my wif's help using her eyes so that a 1
khz tone generates -20 dbfs once we've gone over to digital. I get
satisfactory recordings this way.

Some people think that when they look at the waveform view on their
DAW and the squiggles don't fill up the full track width, they have
a "weak signal." I keep reminding them that -6 dBFS, which is a
reasonably hot level, only uses half the graphic height, so -10 dBFS
is just a wiggly line down the middle. That's why they have zoom
buttons on these things.

I remind them that it's audio, you're supposed to use your friggin'
ears!!!
That's why we ahve another thread about why it has to be so f**ing
loud which has been hijacked into an analog vs digital thread.




Richard Webb,
Electric SPider Productions, New Orleans, La.
REplace anything before the @ symbol with elspider for real email

--



THe knobs turn in both directions". That's why it's called
mixing, otherwise we would call it adding
  #37   Report Post  
Kurt Albershardt
 
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Steve King wrote:
"Lorin David Schultz" wrote in message
news:rGyve.60173$wr.18573@clgrps12...


the standard in digital video these days is 0VU = -20dBFS with
peaks not exceeding -10dBFS. Some facilities nudge the 0VU mark up or
down a bit, but the -10dBFS ceiling seems pretty consistent.



Of course, haven't we all seen the postings about Sony PD150/170 cameras and
their prosumer equivilents VX2000/2001 that will deliver excessively noisy
results at those settings? It is my understanding that other manufacturers
of this category of camera suffer similarly.



Right, -12 dBFS is generally a better reference level for most DVcams.
Having an external preamp or mixer with a decent limiter helps quite a bit.


  #38   Report Post  
Doc
 
Posts: n/a
Default


"Richard Crowley" wrote in message
...

Soundforge definitely makes a distinction between 0db and "clipped".


Soundforge is working on after-the-fact files, not real-time
recording level setting.



Right, that's what I was referring to, material that's already been
recorded. When I got it, it had a few peaks of 0db and some that were
clipped.


  #39   Report Post  
Lorin David Schultz
 
Posts: n/a
Default

"Steve King" wrote:

[...] Shortly after I switched from BetaSP to DVCAM I had to
reschedule an interview that was recorded to the standards suggested
by Lorin on a PD150. The result was simply too noisy to use. It was
an honest mistake by an experienced sound professional who tried to
apply standards that worked with analogue BetaSP to a new digital
format that simply doesn't have the capability to accommodate 20 dB
of headroom.




Hey, don't blame me! I just stated the facts, I didn't set the
standard! g

Our SX camcorders are all calibrated to 0VU = -20dBFS and we don't have
any noise problems. Of course, you could buy a truckload of PD150s for
what one of those costs though.

--
"It CAN'T be too loud... some of the red lights aren't even on yet!"
- Lorin David Schultz
in the control room
making even bad news sound good

(Remove spamblock to reply)


  #40   Report Post  
Lorin David Schultz
 
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Default

"Martin Heffels" wrote:

Avid seems to think 0VU=-14dBFS.


Which Avid? Ours is -20.



I know I am whinging here, but your standard does not have to be my
standard. If you want to speak about such a standard, it is wise to
add in which country you are, so people can apply your suggestions
to their situations.




There seems to be a whole lotta "shoot the messenger" coming from one of
the groups to which this thread is cross-posted. I didn't establish the
standard, I'm just quoting it. Whether anyone chooses to observe it or
not is no skin off my meters... like I said, I didn't come up with it so
my feelings won't be hurt if someone doesn't like it (though a committee
at Sony may take you off their Christmas card list).

Maybe it's different across the pond (I'm in North America), but I don't
think so. I think it's just a case of some people and organizations
choosing to adopt different approaches. Any piece of digital pro video
gear I've ever encountered has the zero VU mark at -20 on the meters
(note that I've not actually seen the Avid to which you refer). Maybe
other devices that I haven't seen are different.

Anyway, how does your comment relate to the original poster's question?

--
"It CAN'T be too loud... some of the red lights aren't even on yet!"
- Lorin David Schultz
in the control room
making even bad news sound good

(Remove spamblock to reply)




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