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• snow : remove an obsolete av_assert2

  9 juillet 2015, par Andreas Cadhalpun

  snow : remove an obsolete av_assert2
  It asserts that the frame linesize is larger than 37, but it can be
  
  smaller and decoding such frames works.
  Before commit cc884a35 src_stride > 7*MB_SIZE was necessary, because the
  
  blocks were interleaved in the tmp buffer and the last block was added
  
  with an offset of 6*MB_SIZE.
  
  It was changed for src_stride <= 7*MB_SIZE to write the blocks
  
  sequentially, hence the larger tmp_step.
  
  After that the assert was only necessary to make sure that the buffer
  
  remained large enough.
  
  Since commit bd2b6b33 s->scratchbuf is used as tmp buffer.
  
  As part of commit 86e107a7 the minimal scratchbuf size was increased to
  
  256*7*MB_SIZE, which is enough for any src_stride <= 7*MB_SIZE.
  Also add a comment explaining the tmp_step calculation.
  Signed-off-by : Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
  

  • [DH] libavcodec/snow.h

• Building ffmpeg on mac results in undefined symbols

  9 juin 2017, par Peter

  Environment : macOS 10.12.5, Xcode 8.3.3, pkg-config installed via brew

  I need to build a minimal version of ffmpeg that supports H.264 decoding. I have downloaded the source for ffmpeg version 3.3.1 and have successfully built it for Windows and Linux. Now, I am trying to build it for mac.

  The specific flags of the configuration that are relevant are :

  --disable-yasm
  
  --disable-everything
  
  --enable-decoder=h264
  
  --enable-decoder=h264_vda
  
  --enable-vda

  After running the configuration, when I run make, all the libraries such as libavcodec.a, libavfilter.a, libavformat.a, are built. However, ffmpeg itself does not get built. The error I get is :

  Undefined symbols for architecture x86_64:
  
    "_ff_vda_create_decoder", referenced from:
  
        _vdadec_init in libavcodec.a(vda_h264_dec.o)
  
    "_ff_vda_destroy_decoder", referenced from:
  
        _vdadec_init in libavcodec.a(vda_h264_dec.o)
  
        _vdadec_close in libavcodec.a(vda_h264_dec.o)
  
  ld: symbol(s) not found for architecture x86_64

  Looks like the functions are defined in ./libavcodec/vda_h264.c. However, it appears vda_h264.c is never compiled. Other vda related files such as vda.c and vda_h264_dec.c do get compiled (and added to libavcodec.a).

  I am thinking perhaps I am missing a configuration flag. Can someone please help ? Regards.

• avcodec/eatgv : Check remaining size after the keyframe header

  28 juillet 2019, par Michael Niedermayer

  avcodec/eatgv : Check remaining size after the keyframe header
  The minimal size which unpack() will not fail on is 5 bytes
  
  Fixes : Timeout (14sec -> 77ms) (testcase 15508)
  
  Fixes : 15508/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_EATGV_fuzzer-5700053513011200
  
  Fixes : 15996/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_EATGV_fuzzer-5751353223151616
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/eatgv.c