Stretching WAV files without losing quality

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Archived from groups: rec.audio.pro,rec.video.desktop (More info?)

I have a 2 hour WAV file that I need to make 1 second longer. I was doing
the video capture and audio was ahead of video by 1 second factor.

So I need to stretch it without losing quality. The effect should be the
same as if I played an analog cassette tape a bit slower. The reason I'm asking
is that I had never had problems with squeezing WAV file (i.e. making them
shorter). But I once tried to stretch the WAV file in GoldWave sound editor
and artifacts such as clicks and distortion were introduced in sound. Any way
to do it without artifacts? Thanks.

--Leonid

PS. The WAV file is 16 bit 48kHz.
 
Archived from groups: rec.audio.pro,rec.video.desktop (More info?)

Leonid Makarovsky wrote:

> I have a 2 hour WAV file that I need to make 1 second longer. I was doing
> the video capture and audio was ahead of video by 1 second factor.
>
> So I need to stretch it without losing quality. The effect should be the
> same as if I played an analog cassette tape a bit slower. The reason I'm asking
> is that I had never had problems with squeezing WAV file (i.e. making them
> shorter). But I once tried to stretch the WAV file in GoldWave sound editor
> and artifacts such as clicks and distortion were introduced in sound. Any way
> to do it without artifacts? Thanks.

Time/pitch scaling has really matured in the last couple of
years years. Steinberg's Wavelab has one of the best
implementations I've encountered. Celemony is a product
made specifically for that purpose, has a lot more
capability than you probably need, is rather expensive, but
has a hell of a reputation. Adobe Audition in its latest
incarnation is also reputed to be quite good but is outside
my experience because it requires XP.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein
 
Archived from groups: rec.audio.pro,rec.video.desktop (More info?)

Leonid Makarovsky wrote:
> I have a 2 hour WAV file that I need to make 1 second longer. I was
> doing
> the video capture and audio was ahead of video by 1 second factor.
>
> So I need to stretch it without losing quality. The effect should be
> the
> same as if I played an analog cassette tape a bit slower. The reason
> I'm asking is that I had never had problems with squeezing WAV file
> (i.e. making them shorter). But I once tried to stretch the WAV file
> in GoldWave sound editor and artifacts such as clicks and distortion
> were introduced in sound. Any way to do it without artifacts? Thanks.
>
> --Leonid
>
> PS. The WAV file is 16 bit 48kHz.


Sound Forge will do this very easily - and without the clicks and pops. For
that matter, the audio tools built into Vegas will do it as well and you'd
have the added benefit of seeing what you're doing. You can get a trial
version of either to see if they do what you want.

Mike
 
Archived from groups: rec.audio.pro,rec.video.desktop (More info?)

Cooledit, Wavelab Soundforge etc will all do a respectanle job, although you
might consider putting in snippets of silence if you can

Don

"Leonid Makarovsky" <venom@cs.bu.edu> wrote in message
news:ckfmll$qi4$1@news3.bu.edu...
> I have a 2 hour WAV file that I need to make 1 second longer. I was doing
> the video capture and audio was ahead of video by 1 second factor.
>
> So I need to stretch it without losing quality. The effect should be the
> same as if I played an analog cassette tape a bit slower. The reason I'm
asking
> is that I had never had problems with squeezing WAV file (i.e. making them
> shorter). But I once tried to stretch the WAV file in GoldWave sound
editor
> and artifacts such as clicks and distortion were introduced in sound. Any
way
> to do it without artifacts? Thanks.
>
> --Leonid
>
> PS. The WAV file is 16 bit 48kHz.
 
Archived from groups: rec.audio.pro,rec.video.desktop (More info?)

On Tue, 12 Oct 2004 01:34:59 -0700, Bob Cain
<arcane@arcanemethods.com> wrote:

>
>
>Leonid Makarovsky wrote:
>
>> I have a 2 hour WAV file that I need to make 1 second longer. I was doing
>> the video capture and audio was ahead of video by 1 second factor.
>>
>> So I need to stretch it without losing quality. The effect should be the
>> same as if I played an analog cassette tape a bit slower. The reason I'm asking
>> is that I had never had problems with squeezing WAV file (i.e. making them
>> shorter). But I once tried to stretch the WAV file in GoldWave sound editor
>> and artifacts such as clicks and distortion were introduced in sound. Any way
>> to do it without artifacts? Thanks.
>
>Time/pitch scaling has really matured in the last couple of
>years years. Steinberg's Wavelab has one of the best
>implementations I've encountered. Celemony is a product
>made specifically for that purpose, has a lot more
>capability than you probably need, is rather expensive, but
>has a hell of a reputation. Adobe Audition in its latest
>incarnation is also reputed to be quite good but is outside
>my experience because it requires XP.

Magix, who market Samplitude, sell a less powerful version called
"Magix Studio" or something like that for around $50, it's a very
powerful app that misses a few of the high end features of Samplitude,
but the time stretch should be in there and it works very well. I
think you can download a trial version and check it out. Also there
is a good time-stretch plugin from Prosoniq called "Time Factory" that
is excellent.

Al
 
Archived from groups: rec.audio.pro,rec.video.desktop (More info?)

In article <ckfmll$qi4$1@news3.bu.edu> venom@cs.bu.edu writes:

> I have a 2 hour WAV file that I need to make 1 second longer. I was doing
> the video capture and audio was ahead of video by 1 second factor.

Is this one second (cumulative) off at the end of the two hour video
program? Why not just find a few places where the sync is far enough
to be noticable (like a sound that doesn't occur right in time with
the image of what makes the sound), chop the audio file, and drag it
into place? Line up all the important parts and the rest of it won't
matter. If you have to make the time come out exact, you can always
find other places to chop it. This is easier, less potentially
damaging to the audio (but back up your file first before cutting it)
and will give you a better production.


--
I'm really Mike Rivers (mrivers@d-and-d.com)
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 here: double-m-eleven-double-zero at yahoo
 
Archived from groups: rec.audio.pro,rec.video.desktop (More info?)

In rec.audio.pro Mike Kujbida <kujfam-misleadingspam@sympatico.ca> wrote:
: Sound Forge will do this very easily - and without the clicks and pops. For
: that matter, the audio tools built into Vegas will do it as well and you'd
: have the added benefit of seeing what you're doing. You can get a trial
: version of either to see if they do what you want.

Mike,

I have SoundForge 5.0. What option of stretching should I use? There're many
there. I also have the tool called SSRC which is the best tool for resampling.
I was thinking maybe I should resample this WAV file to say 48.001kHz and then
tell the program to play it back at 48kHz?

--Leonid
 
Archived from groups: rec.audio.pro,rec.video.desktop (More info?)

In rec.audio.pro Don Nafe <dnafe@magma.ca> wrote:
: Cooledit, Wavelab Soundforge etc will all do a respectanle job, although you
: might consider putting in snippets of silence if you can

What does that mean?

--Leonid
 
Archived from groups: rec.audio.pro,rec.video.desktop (More info?)

"Leonid Makarovsky" <venom@cs.bu.edu> wrote in message
news:ckgpho$hoa$2@news3.bu.edu...
> In rec.audio.pro Don Nafe <dnafe@magma.ca> wrote:
> : Cooledit, Wavelab Soundforge etc will all do a respectanle job, although
> you
> : might consider putting in snippets of silence if you can
>
> What does that mean?

Cut the audio track apart at several natural pauses and slip it back
into sync so that the error doesn't accumulate.
 
Archived from groups: rec.audio.pro,rec.video.desktop (More info?)

Leonid Makarovsky wrote:

> I have SoundForge 5.0. What option of stretching should I use? There're many
> there. I also have the tool called SSRC which is the best tool for resampling.
> I was thinking maybe I should resample this WAV file to say 48.001kHz and then
> tell the program to play it back at 48kHz?

SRC will give an aritfact free result but the the frequency
content of the material is also scaled. If you want the
pitch to remain unchaged, SRC is not the way to do it.

Time/pitch scaling is much different than source rate
conversion (although SRC may be part of the internal
process). SRC has a theoretical solution that can be
calculated to any desired accuracy. Time/pitch scaling
doesn't have a theoretical solution (it's non-causal and
non-linear in really nasty ways) and is approached instead
with various hueristics. The heuristics have dramatically
improved in recent years for almost all products that
include the capability.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein
 
Archived from groups: rec.audio.pro,rec.video.desktop (More info?)

On 12 Oct 2004 04:30:45 GMT, Leonid Makarovsky <venom@cs.bu.edu>
wrote:

>I have a 2 hour WAV file that I need to make 1 second longer. I was doing
>the video capture and audio was ahead of video by 1 second factor.
>
>So I need to stretch it without losing quality. The effect should be the
>same as if I played an analog cassette tape a bit slower. The reason I'm asking
>is that I had never had problems with squeezing WAV file (i.e. making them
>shorter). But I once tried to stretch the WAV file in GoldWave sound editor
>and artifacts such as clicks and distortion were introduced in sound. Any way
>to do it without artifacts? Thanks.

Playing an analogue tape slower would shift pitch as well as change
length. Though with a change of this tiny magnitude, it's hardly an
issue.

"Audio ahead of video" implies that they just need aligning. But you
mean the overall lengths are different and you really have an audio
file that, though aligned to video at the start, ends up 1 sec.
behind?

1 sec. in two hours. That's a tiny ratio. I'm not sure that any wave
editor will accept a resampling factor of 0.9998611 and, if it did,
do anything useful with it.

Within the 2 hours of audio, can you find 10 places where you could
unobtrusively insert 0.1 sec of silence (or paste in that amount of
ambient sound, if more appropriate? Would that get things near
enough?

CubaseFAQ www.laurencepayne.co.uk/CubaseFAQ.htm
"Possibly the world's least impressive web site": George Perfect
 
Archived from groups: rec.audio.pro,rec.video.desktop (More info?)

Leonid Makarovsky wrote:
> In rec.audio.pro Mike Kujbida <kujfam-misleadingspam@sympatico.ca>
> wrote:
>> Sound Forge will do this very easily - and without the clicks and
>> pops. For that matter, the audio tools built into Vegas will do it
>> as well and you'd have the added benefit of seeing what you're
>> doing. You can get a trial version of either to see if they do what
>> you want.
>
> Mike,
>
> I have SoundForge 5.0. What option of stretching should I use?
> There're many there. I also have the tool called SSRC which is the
> best tool for resampling. I was thinking maybe I should resample this
> WAV file to say 48.001kHz and then tell the program to play it back
> at 48kHz?
>
> --Leonid


Not sure is SF 5.0 has it. I've got SF 6.0 and I'd use the Process > Time
Stretch option myself. I just tried this with a 2 hr. clip and it took
about 2 min. to process. Because the stretch amount is negligible (0.01%),
you won't hear the difference.

Mike
 
Archived from groups: rec.video.desktop (More info?)

Audition, Sound Forge and Premiere Pro do it easily without loss of
quality.


On 12 Oct 2004 04:30:45 GMT, Leonid Makarovsky <venom@cs.bu.edu>
wrote:

>I have a 2 hour WAV file that I need to make 1 second longer. I was doing
>the video capture and audio was ahead of video by 1 second factor.
>
>So I need to stretch it without losing quality. The effect should be the
>same as if I played an analog cassette tape a bit slower. The reason I'm asking
>is that I had never had problems with squeezing WAV file (i.e. making them
>shorter). But I once tried to stretch the WAV file in GoldWave sound editor
>and artifacts such as clicks and distortion were introduced in sound. Any way
>to do it without artifacts? Thanks.
>
>--Leonid
>
>PS. The WAV file is 16 bit 48kHz.
 
Archived from groups: rec.video.desktop (More info?)

Leonid Makarovsky wrote:
>I have a 2 hour WAV file that I need to make 1 second longer. I was doing
>the video capture and audio was ahead of video by 1 second factor.
>
>So I need to stretch it without losing quality. The effect should be the
>same as if I played an analog cassette tape a bit slower. The reason I'm
>asking
>is that I had never had problems with squeezing WAV file (i.e. making them
>shorter). But I once tried to stretch the WAV file in GoldWave sound editor
>and artifacts such as clicks and distortion were introduced in sound. Any
>way
>to do it without artifacts? Thanks.

How are you joining audio and video? If you are using NLE, it is
simple enough to break the audio track at several places where
there are natural pauses and slip it back in sync. IMHO, preferable
to trying to stretch the entire 2 hour file!
 
Archived from groups: rec.audio.pro,rec.video.desktop (More info?)

In rec.audio.pro Bob Cain <arcane@arcanemethods.com> wrote:
: SRC will give an aritfact free result but the the frequency
: content of the material is also scaled. If you want the
: pitch to remain unchaged, SRC is not the way to do it.


I don't want pitch to remain unchanged. The problem is that SSRC will not
convert a WAV file with 47999Hz to 48000Hz. It says that it must be dividable
by 2 or 3.

So I guess I'm stuck with SoundForge 5.0. I don't like how GoldWave does it.

--Leonid
 
Archived from groups: rec.audio.pro,rec.video.desktop (More info?)

"Leonid Makarovsky" <venom@cs.bu.edu> skrev i en meddelelse
news:ckfmll$qi4$1@news3.bu.edu...
> I have a 2 hour WAV file that I need to make 1 second longer. I was doing
> the video capture and audio was ahead of video by 1 second factor.
>
> So I need to stretch it without losing quality. The effect should be the
> same as if I played an analog cassette tape a bit slower. The reason I'm
asking
> is that I had never had problems with squeezing WAV file (i.e. making them
> shorter). But I once tried to stretch the WAV file in GoldWave sound
editor
> and artifacts such as clicks and distortion were introduced in sound. Any
way
> to do it without artifacts? Thanks.
>
> --Leonid
>
> PS. The WAV file is 16 bit 48kHz.

Just duplicate every 7200th sample.
 
Archived from groups: rec.audio.pro,rec.video.desktop (More info?)

"Leonid Makarovsky" <venom@cs.bu.edu> wrote in message
news:ckhssg$nhg$1@news3.bu.edu...
> In rec.audio.pro Bob Cain <arcane@arcanemethods.com> wrote:
> : SRC will give an aritfact free result but the the frequency
> : content of the material is also scaled. If you want the
> : pitch to remain unchaged, SRC is not the way to do it.
>
>
> I don't want pitch to remain unchanged. The problem is that SSRC will not
> convert a WAV file with 47999Hz to 48000Hz. It says that it must be
> dividable
> by 2 or 3.

Well... What would it do? Mathematically it would only be adding ONE sample
per second.


>
> So I guess I'm stuck with SoundForge 5.0. I don't like how GoldWave does
> it.
>
> --Leonid
 
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