Hi all,

I'm new here so please just point me at a faq or
whatever if this has been done to death before.

I'm transferring old audio tapes to wav playing
back on a Revox A77 but some were recorded on an
older machine where the speed wasn't very accurate
but could be reasonably consistent. I'm looking
for a utility that will let me process the wav
files to change the speed by an arbitrary
percentage, presumably by simple interpolation.
I'm not looking for great quality as the
originals were poor quality and quite noisy
anyway. Some may even have been at 1 7/8 ips
but they have sentimental value. I'd rather use
some shareware solution than write my own so does
anyone have any suggestions.

Thanks
George

On Fri, 17 Sep 2004 18:44:37 +0100, "George Dishman"
wrote:

Hi all,

I'm new here so please just point me at a faq or
whatever if this has been done to death before.

I'm transferring old audio tapes to wav playing
back on a Revox A77 but some were recorded on an
older machine where the speed wasn't very accurate
but could be reasonably consistent. I'm looking
for a utility that will let me process the wav
files to change the speed by an arbitrary
percentage, presumably by simple interpolation.

The program you need should change the sample rate. Most audio editors
can do that. The function to look for is "change time/pitch".
I use Adobe Audition for that and it offeres three functions:
"change time (and preserve pitch)" and "change pitch (and preserve
time)" require a hefty interpolation that may leave some artifacts.
Changing both time and pitch are done by change of sample rate
(which is done without artifacts).

Norbert

"George Dishman" wrote in message
...
I'm transferring old audio tapes to wav playing
back on a Revox A77 but some were recorded on an
older machine where the speed wasn't very accurate
but could be reasonably consistent. I'm looking
for a utility that will let me process the wav
files to change the speed by an arbitrary
percentage, presumably by simple interpolation.
I'm not looking for great quality as the
originals were poor quality and quite noisy
anyway. Some may even have been at 1 7/8 ips
but they have sentimental value. I'd rather use
some shareware solution than write my own so does
anyone have any suggestions.

The best freeware I know of for changing sample rate, is Voxengo R8Brain.
You can resample at a higher or lower rate, but set the output file headers
for the original sample rate. This has the same effect as increasing or
decreasing tape speed. Resample quality is excellent.

The other problem for 1 7/8 ips recordings, assuming your A77 doesn't have 1
7/8 ips playback, is that the EQ will be wrong. You can change that in
software too.

TonyP.

"TonyP" wrote in message
u...
...
The best freeware I know of for changing sample rate, is Voxengo R8Brain.
You can resample at a higher or lower rate, but set the output file headers
for the original sample rate. This has the same effect as increasing or
decreasing tape speed. Resample quality is excellent.

My thanks to you and Norbert, this is exactly
what I was looking for.

The other problem for 1 7/8 ips recordings, assuming your A77 doesn't have 1
7/8 ips playback, is that the EQ will be wrong. You can change that in
software too.

Good point, I hadn't thought of that. I doubt
the original quality is good enough for it to
show up as most was recorded from AM radio
thirty years ago but now I know where to look.

thanks again
George

On Sat, 18 Sep 2004 15:58:29 +1000, "TonyP"
wrote:

The best freeware I know of for changing sample rate, is Voxengo R8Brain.
You can resample at a higher or lower rate, but set the output file headers
for the original sample rate. This has the same effect as increasing or
decreasing tape speed. Resample quality is excellent.

In deed, it's a great program. I did some checks: I used a recording
with 44.1 kHz original sample rate and tried to speed up to 102%.
So I patched 45 kHz into the file and started r8brain. Output sample
rate was then selected as 44.1 kHz. No problems. The file got
converted and it sounded ok. To verify that is was converted at all
I played back both files at the same time - the difference is clearly
audible.

Another fine program, Shibatch Sample Rate Converter (ssrc.exe), tells
me that the ratio 44100/45000 is not in its tables. It does a good job
on converting well known sample rates though.

Norbert