Баг с обрезанием дорожек при ресемплинге

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willrain
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Баг с обрезанием дорожек при ресемплинге

Post by willrain » Sat Jan 29, 2011 8:18 pm

Собственно, все подробно изложено в этом топике - http://www.linux.org.ru/forum/talks/5849008 - после ресемплинга итоговая дорожка оказывается короче исходной с потерей данных в разнице.

Gale Andrews
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Re: Баг с обрезанием дорожек при ресемплинге

Post by Gale Andrews » Sun Jan 30, 2011 8:12 pm

Если вы хотите сообщить ошибок вы должны делать это на английском языке здесь:
http://audacityteam.org/contact/#feedback

Если речь идет о вставили клипов, которые требуют ресамплинг находясь на неправильной длины и скорости, это зафиксировано в последней версии кода (ствол).




Gale
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Gale Andrews
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Re: Баг с обрезанием дорожек при ресемплинге

Post by Gale Andrews » Mon Jan 31, 2011 5:52 pm

willrain wrote: 1. Open any audio track (or just use tone generator)
2. Take a look at time counter or use one track as reference
3. Go to the "Tracks - Resample" and enter, for example, 192000
4. Compare original and resampled track - now resampled track is shorter
(and all information between 3,28895 and 3,30000 is lost

Reproduced on Debian Squeeze and Gentoo, both versions are 1.3.12.
Thanks for writing to [email protected] and confirming the bug in English. I cannot reproduce the significant length change on Windows 7 in either 1.3.12 Release or SVN HEAD (both of which use libresample for resampling). So I think the bug you are seeing isn't the problem I mentioned where you get a length and speed change if you paste a clip at a given sample rate into a track at another rate. That issue is now fixed in HEAD.

I can reproduce your issue in the Ubuntu-packaged 1.3.12 in which Ubuntu use libsamplerate instead of libresample, so I assume it to be an issue with libsamplerate or how Audacity works with it. There is no pitch change in the resampled track. Can you please look at Help > About Audacity (Build Information tab) and confirm under "Core Libraries" that libsamplerate is being used?

I also note the resampling to 192000 Hz takes 5 minutes as opposed to 30 seconds using libresample on Windows, and that changing the project rate to the rate you want to resample to, then resampling does not avoid the problem. Fortunately, changing the project rate and exporting as WAV still works correctly, so that is the workaround.

Trying your steps on Windows 7 in SVN HEAD on a 30 second 44100 Hz tone, I did according to Selection Toolbar get 5,760,002 samples in the resampled track instead of the expected 5,760,000, and similar "one or two samples extra" results if I resampled the tone to other rates. The resampled tracks do appear slightly longer. We'd have to investigate that further.



Gale
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willrain
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Re: Баг с обрезанием дорожек при ресемплинге

Post by willrain » Mon Jan 31, 2011 8:24 pm

Can you please look at Help > About Audacity (Build Information tab) and confirm under "Core Libraries" that libsamplerate is being used?
Yes,
Core Libraries
libsamplerate (Sample rate conversion) Enabled

Code: Select all

[email protected]:~$ LANG=C apt-cache policy libsamplerate0
libsamplerate0:
  Installed: 0.1.7-3
If you have time, a quick summary there of my answer translated to Russian may perhaps help someone.
Ок, из той половины, что я понял - что на винде используется другая библиотека для ресемплинга и проблема либо в libsamplerate, либо в том, как редактор с ней работает. В общем, будут разбираться ).

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