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• 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.

• How to "extend" aws docker base image (.net core from scratch) by ... libs/ubuntu/ffmpeg ?

  26 avril 2022, par Nigrimmist

  i would like to use AWS Lambda through the image containers using .net core 3.1 and it is works fine for me in simplest code case. But i stucked with next scenario :

  


  By default, aws provide base image with .net core with aws libs based on "from scratch". So as i know, it minimal Linux that does not contains even package manager.

  


  I need to work with ffmpeg in the code, but to do it i need to install few packages and ... fmpeg. I have working code on image

  


  FROM mcr.microsoft.com/dotnet/runtime:3.1-bionic


  


  It is ubuntu with .net core runtime. But what is the right strategic in case of AWS Lambda image ? How can i ... merge them ?.

  


  Have few ideas, but not sure :

  


  

  1. use as is FROM public.ecr.aws/lambda/dotnet:core3.1 and try to install package manager, all depenendencies to use ffmpeg and so on ?

  


  2. Use mcr.microsoft.com/dotnet/runtime:3.1-bionic, somehow add required by amazon dependencies (how ? download content and attach from local ?) and configure it to run in Lambda runtime ?

  


  3. ... ?

  


  


  Will be glad to hear where is the solution here. Thanks !

  


• 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