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View Full Version : MPEG 1 Layer 2 a.k.a. MP2 software decoder?

pandy
3rd July 2015, 09:02
Searching for good MP2 software decoder - seem that MP2 decoder in ffmpeg is limited to 16bits, foobar2000 decoder is also limited and seem behave unstable in particular situations...
So is there any 24 - xx bit int of float decoder available (open source / freeware preferred).

Thnx in Advance!
nevcairiel
3rd July 2015, 09:32
ffmpeg has a float decoder (ie. -c:a mp2float) . Is that one only producing 16-bit of actual relevant data?
pandy
3rd July 2015, 10:00
ffmpeg has a float decoder (ie. -c:a mp2float) . Is that one only producing 16-bit of actual relevant data?

I need to decode MP2 to PCM (with at least 24 bit) - currently ffmpeg with @ffmpeg -i %1 -vn -c:a pcm_f32le -y %1_pcm_f32le.wav produce 32 bit float PCM WAV but signal inside (source is MP2) is 16 bit.
nevcairiel
3rd July 2015, 11:05
Try adding "-c:a mp2float" before the "-i" command, that should make it use the float decoder. No idea why it defaults to the s16 decoder...
Not sure how much more precision that will actually give you, but at least its not artificially cut down to 16-bit.
pandy
3rd July 2015, 15:55
Try adding "-c:a mp2float" before the "-i" command, that should make it use the float decoder. No idea why it defaults to the s16 decoder...
Not sure how much more precision that will actually give you, but at least its not artificially cut down to 16-bit.


Thx, indeed default is not float one - but still i see no improvement - depends on source (encoder) and decoder i see strange results (discrete tones not existing in source) - this is very strange - such low quality... (between -70 and -90dBFS noise floor).
LoRd_MuldeR
11th July 2015, 18:55
What about mpg123 decoder library?
http://mpg123.de/
pandy
15th July 2015, 09:19
What about mpg123 decoder library?
http://mpg123.de/

Thx for tip - i had impression that is no longer actively maintained and such surprise... there is bug fix from 2015-05-24 (but no binaries yet) - i will do test (in free time and when binaries will be available) and provide feedback.
LoRd_MuldeR
15th July 2015, 18:43
Thx for tip - i had impression that is no longer actively maintained and such surprise... there is bug fix from 2015-05-24 (but no binaries yet) - i will do test (in free time and when binaries will be available) and provide feedback.

If you need up-to-date binaries, look here ;)
https://github.com/lordmulder/LameXP/tree/master/res/tools
pandy
16th July 2015, 12:15
If you need up-to-date binaries, look here ;)
https://github.com/lordmulder/LameXP/tree/master/res/tools

:thanks:

and btw - is there any reference audio MPEG-1 Layer I and II decoder (similar to ISO MPEG-2 video decoder - mpeg2dec)

I should say downloadable reference decoder as buying ISO/IEC TR 13818-5:2005 have no sense to me...