[Ffmpeg-devel] Re: WMA decoder improvement

[Patrice Bensoussan]

 >Ian Braithwaite skrev:
 >> Hi,
 >>
 >>

Hi,

 >> Here's a little improvement to wma decoding.
 >>
 >> I've compared the decoded output against that produced by the  
wmadmo dll
 >> used with mplayer.
 >>
 >> Testing on "...samples/A-codecs/WMA/Bangles 01 - Walk Like An  
 >Egyptian.wma",
 >> it reduces the difference between MS and ffmpeg from
 >>   max +-4142, rms 21.0  to  max +-575, rms 1.3.
 >>
 >> On a 30s clip I use for testing ("g_64k.wma", can't remember now  
where it >came
 >> from:-/) the improvement is from
 >>   max +-1361, rms = 9.3  to  max +-1, rms = 0.04 (!!)
 >>
 >>
 >> Here's what it does.
 >> Exponents can be reused from one block to the next.
 >> In wma, block sizes vary, for example between 128,256,512,1024  
and 2048 >samples.
 >> Currently, when reusing exponents in blocks with a different  
block size,
 >> the exponent block is down or up sampled to the new size.
 >> So a block of exponents can be resized from 512 -> 256 samples,  
and then
 >> resized back again from 256 -> 512 samples,
 >> discarding and duplicating every other sample, respectively.
 >>
 >> The patch keeps the original exponent blocks, and resizes (on the  
fly) to
 >> each new block size.
 >>
 >>
 >>  wma.h    |    1
 >>  wmadec.c |   79 +++++++++++++++++ 
+-------------------------------------->-------
 >> 2 files changed, 24 insertions(+), 56 deletions(-)
 >>
 >
 >Make test and make fulltest regressions passed thus applied.
 >
 >>
 >> There seem to be quite a few variants of wma, so I can't be sure  
that
 >> this is the right thing to do in all cases.
 >>
 >> Also, to compare against the MS codec, I had to prevent the first  
two
 >> blocks from being output.
 >> There's a little patch for that too, but I'm pretty sure it doesn't
 >> do the right thing in all cases.
 >> I've attached it in case anyone wants to reproduce my measurements.
 >>
 >>
 >> Regards,
 >> Ian
 >>
 >>  
------------------------------------------------------------------------
 >
 >
 >MvH
 >Benjamin Larsson

This patch completely breaks the decoding of sample files I have.  
Moreover it generate a lot of warnings at runtime related to double  
free() calls.
See ffmpeg output below:

[patriceb at patrice-bensoussans-ibook-g4 ~/tmp/WMA/ffmpeg/ppc]$ ./ 
ffmpeg -i ~/tmp/WMA/songs/blacksmith.wma ~/Desktop/test.mp3
FFmpeg version SVN-r8627, Copyright (c) 2000-2007 Fabrice Bellard, et  
al.
   configuration: --cc=gcc-3.3 --enable-pthreads --disable-network -- 
disable-vhook --enable-small --enable-libmp3lame --enable-libfaac -- 
disable-decoder=cook --extra-ldflags=-L/Users/patriceb/tmp/WMA/opt/ 
lib --extra-cflags=-I/Users/patriceb/tmp/WMA/opt/include --enable-gpl  
--enable-x264 --enable-liba52 --enable-libfaad
   libavutil version: 49.4.0
   libavcodec version: 51.40.2
   libavformat version: 51.11.0
   built on Apr  5 2007 21:33:38, gcc: 3.3 20030304 (Apple Computer,  
Inc. build 1819)
Input #0, asf, from '/Users/patriceb/tmp/WMA/songs/blacksmith.wma':
   Duration: 00:00:34.2, start: 2.600000, bitrate: 164 kb/s
   Stream #0.0: Audio: wmav2, 44100 Hz, stereo, 160 kb/s
Output #0, mp3, to '/Users/patriceb/Desktop/test.mp3':
   Stream #0.0: Audio: mp3, 44100 Hz, stereo, 64 kb/s
Stream mapping:
   Stream #0.0 -> #0.0
Press [q] to stop encoding
size=     266kB time=34.1 bitrate=  64.0kbits/s
video:0kB audio:266kB global headers:0kB muxing overhead 0.000000%
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0x4380d54d; This could be a double free(), or free() called with the  
middle of an allocated block; Try setting environment variable  
MallocHelp to see tools to help debug
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0x437d337d; This could be a double free(), or free() called with the  
middle of an allocated block; Try setting environment variable  
MallocHelp to see tools to help debug
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0xa; This could be a double free(), or free() called with the middle  
of an allocated block; Try setting environment variable MallocHelp to  
see tools to help debug
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0x1c4bf4; This could be a double free(), or free() called with the  
middle of an allocated block; Try setting environment variable  
MallocHelp to see tools to help debug
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0x1b9ad8; This could be a double free(), or free() called with the  
middle of an allocated block; Try setting environment variable  
MallocHelp to see tools to help debug
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0x9; This could be a double free(), or free() called with the middle  
of an allocated block; Try setting environment variable MallocHelp to  
see tools to help debug
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0x1c4bf4; This could be a double free(), or free() called with the  
middle of an allocated block; Try setting environment variable  
MallocHelp to see tools to help debug
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0x1b9ad8; This could be a double free(), or free() called with the  
middle of an allocated block; Try setting environment variable  
MallocHelp to see tools to help debug
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0x8; This could be a double free(), or free() called with the middle  
of an allocated block; Try setting environment variable MallocHelp to  
see tools to help debug
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0x1c4bf4; This could be a double free(), or free() called with the  
middle of an allocated block; Try setting environment variable  
MallocHelp to see tools to help debug
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0x1b9ad8; This could be a double free(), or free() called with the  
middle of an allocated block; Try setting environment variable  
MallocHelp to see tools to help debug
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0x7; This could be a double free(), or free() called with the middle  
of an allocated block; Try setting environment variable MallocHelp to  
see tools to help debug
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0x1c4bf4; This could be a double free(), or free() called with the  
middle of an allocated block; Try setting environment variable  
MallocHelp to see tools to help debug
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0x1b9ad8; This could be a double free(), or free() called with the  
middle of an allocated block; Try setting environment variable  
MallocHelp to see tools to help debug
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0x6; This could be a double free(), or free() called with the middle  
of an allocated block; Try setting environment variable MallocHelp to  
see tools to help debug
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0x1c4bf4; This could be a double free(), or free() called with the  
middle of an allocated block; Try setting environment variable  
MallocHelp to see tools to help debug
ffmpeg(23258) malloc: ***  Deallocation of a pointer not malloced:  
0x1b9ad8; This could be a double free(), or free() called with the  
middle of an allocated block; Try setting environment variable  
MallocHelp to see tools to help debug

Patch should be reverted IMHO until it gets fixed. Converted mp3 file  
is not audible.

Regards,
Patrice