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MP3 maximum bit rate issue

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Samrat Dutta
MP3 maximum bit rate issue
on Jul 25, 2013 at 8:02:25 am

I have tried to create a mp3 file with some specific parameter like maximum bitrate , duration ,sampling rate, channel. For this I have used ffmpeg Libmp3lame library with the following command ;

ffmpeg -i OLD1.mp3 -codec:a libmp3lame -ar 32000 -ab 56k -ac 2 -q:a 1 -t 00:03:00.000 -y NEW-1.mp3

Here we need to create a mp3 file with maxbit rate 56kbps. So I used -ab 56K but unfortunately It creates with 64K max bit rate.
So I want to know , is there any other command to create the file with proper maxbit rate?

and another question is what is the command in ffmpeg to get the max bit rate?

Answer of the above two questions are relly helpful to me.


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Angelo Lorenzo
Re: MP3 maximum bit rate issue
on Jul 25, 2013 at 9:48:27 pm

Please remove -v:a 1 as this maps to LAME's quality setting, it overrides -ar 56K.

Edit: This looks like it produces a CBR file. You can use -v:a 9 for a closer approximation. Average bitrate encoding (A variant on how VBR is calculated) doesn't look achievable through FFMPEG so you may need to use LAME's direct executable in the command line if you need absolute accuracy.

Angelo Lorenzo

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