Re: [dvd::rip] Sound distortion

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Dnia 2005-07-24 12:03, Użytkownik Jörn Reder napisał:
> Jurek Bartuszek wrote:
> You could transcode a smaller test chunk with AC3 passthrough enabled to
> see, erm, hear ;) if the original stream is already distorted in some 
> way.
> 
> If not, you should encode to Ogg/Vorbis. If this works, something with 
> your transcode / MP3 encoding is broken, if not we have a more general 
> transcode audio processing problem. Do you use any audio filter? Do you
> use volume rescaling? Probably rescaling is too aggressive, so the sound
> distorts?

Thanks for you reply! The original AC3 stream is not distorted at all.

- - How do I transcode to Ogg/Vorbis? I can only choose from MP3 and AC3
- - No audio filters are being used (well, I didn't set any and the
filters list is empty).
- - I've tried various volume rescaling values. That changes nothing.

Remember, that the sound not only gets distorted - it is also balanced
to the left a little bit.

Below I post URL's to the chunks to compare original and encoded
streams. It's a pretty good idea to put on the headphones in order to
hear the difference clearly:

Here is the AC3 chunk:
http://gamma.mini.pw.edu.pl/~bartuszekj/mt/mt_dvdrip_ac3.avi

Here is the same chunk transcoded with dvdrip (Mp3, 192kbps, 48000Hz)
http://gamma.mini.pw.edu.pl/~bartuszekj/mt/mt_dvdrip_mp3.avi

The difference is obvious, I suppose. In order to check whether it's a
lame-regarded problem, I've done a little testing:

Ripped an audio cd: http://gamma.mini.pw.edu.pl/~bartuszekj/mt/mt.wav

$ lame -b 192 mt.wav mt.mp3

http://gamma.mini.pw.edu.pl/~bartuszekj/mt/mt.mp3

In this case the distortion and balance problems are not present.

Any ideas?

Regards,

Jurek Bartuszek
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