[FFmpeg-user] Input 5.1 DTS, output 2.0 MP3: Atrocious Quality

Carl Eugen Hoyos cehoyos at ag.or.at
Sat May 16 09:52:12 CEST 2015

John L <orionfyre <at> hotmail.com> writes:

> ffmpeg version 2.5.6-0ubuntu0.15.04.1

Please test current FFmpeg git head, see 
(Please do not test 2.6)

> ffmpeg -i inter.dts -ac 2 -c libmp3lame inter-test.mp3
> This audio sample has the exact same audio defects as 
> in the shrunken video 
> Converting it to a stereo wave format, and then 
> converting into an mp3:
> ffmpeg -i inter.dts -ac 2 -c pcm_s32le inter.wav && 
> ffmpeg -i inter.wav -c libmp3lame inter.mp3
> both inter.wav and inter.mp3 are confirmed to be 
> GOOD stereo copies of the audio with no defects.

Please test the following:
$ ffmpeg -i inter.dts -ac 2 out16.wav
$ ffmpeg -i inter.dts -ac 2 -acodec pcm_s32le out32.wav
$ ffmpeg -i inter.dts -ac 2 -ab 640k out.ac3
$ ffmpeg -i inter.dts -ac 2 -ab 320k out.mp2

Iiuc, out32.wav sounds ok. Do the other three files 
sound ok for you or not?

> Until I have a solution I've already edited my 
> services to perform this intermediary wave step 
> work-around on all conversions.

You can do the intermediate step within FFmpeg, 
just play with -af aformat=s32.

Thank you, Carl Eugen

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