[Libav-user] Noise on mms-stream playing

Alexey Belkevich belkevich at mlsdev.com
Thu Feb 7 08:34:01 CET 2013

> If I understand your use-case correctly, you have written 
> a software that uses libavcodec internally to decode wma.
> Your software works fine with older versions of libavcodec 
> (FFmpeg 0.11) but not with newer versions of libavcodec 
> (although ffmpeg - the command line application - still 
> works fine, its console outputs looks slightly different 
> though).

> The reason is that the wma decoder has changed. wma 
> internally uses floats, in the past (until FFmpeg 0.11) 
> these floats were converted to s16 (16 bit integer) inside 
> the decoder. For clarity reasons, it was decided that it 
> makes no sense to convert these floats into int's inside 
> the decoder.
> The decoder now outputs (planar) floats (the native wma format), 
> assuming you need int's (s16) in your application, you now have 
> to use the aconvert filter (or libswresample directly) to 
> convert from float to int16.

Ok, I will try to use it
> Please understand that it is not a solution for you to use 
> 0.11 forever because new features are not backported to 
> old versions of FFmpeg.

Of course, thats why I'm writing here =) 
> I hope that clears it up, Carl Eugen

Now everything is clear. Thank you very much Carl! 

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