[FFmpeg-devel] [PATCH] WMA Lossless: reset channel residues between subframes

Mashiat Sarker Shakkhar mashiat.sarker at gmail.com
Sat Apr 14 21:04:58 CEST 2012

On 4/15/2012 12:38 AM, Jakub Stachowski wrote:
> For first test I used WMA file from bug #1055:
> Decoded with dBpoweramp or Microsoft's wmal2pcm.exe I got 1410612 samples.
> Decoded with ffmpeg (without taking skip value): 1413120
> During decoding last frame, get_bits1() returned 460 samples to skip.
> Difference is 2048+460 samples, so it should skip one full frame (I
> wonder which one) and 460 from last one?

Are you just assuming that samples_per_frame = 2048 or did you check?

> Next test: hand-crafted file with 15000 samples. All of them zeros apart
> from last 14 bytes, then encoded with MS Expression Encoder
> wmal2pcm.exe decoded it perfectly
> ffmpeg after taking skip value into account also created file with right
> length, however all samples were 0 (last 14 non-zero bytes got destroyed).

Why don't you share your WIP patch or git tree with us? If possible do 
share the samples too.

> So it is step in right direction, but not completely correct yet.

I'd say you are stepping in the right direction. May be there are quirks 
that we are not aware of. It's easy enough to compare the bitstream 
reads with refcode. Share your code so that I can test.



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