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• avfilter/af_amix : Fix double-free of AVFilterChannelLayouts on error

  7 août 2020, par Andreas Rheinhardt

  avfilter/af_amix : Fix double-free of AVFilterChannelLayouts on error
  The query_formats function of the amix filter tries to allocate a list
  
  of channel layouts which are attached to more permanent objects
  
  (an AVFilter's links) for storage afterwards on success. If attaching
  
  a list to a link succeeds, the link becomes one of the common owners
  
  of the list. Yet if a list has been successfully attached to links (or if
  
  there were no links to attach it to in which case
  
  ff_set_common_channel_layouts() already frees the list) and an error
  
  happens lateron, the list was manually freed, which is wrong, because
  
  the list has either already been freed or it is owned by its links in
  
  which case these links' pointers to their list will become dangling and
  
  there will be double-frees/uses-after-free when these links are cleaned
  
  up automatically.
  This commit fixes this by removing the custom freeing code ; this is made
  
  possible by using the list in ff_set_common_channel_layouts() directly
  
  after its allocation (without anything that can fail in between).
  Notice that ff_set_common_channel_layouts() is buggy itself which can
  
  lead to double-frees on error. This is not fixed in this commit.
  Reviewed-by : Nicolas George <george@nsup.org>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavfilter/af_amix.c

• sws_freeContext/sws_scale/sws_getContext errors while compiling ffmpeg libraries

  17 avril 2014, par Steve

  I have been working on ffmpeg for one of my projects. I am trying to utilize the ffmpeg static or shared libraries for my Android x86 project. I have followed the steps provided by Intel on this weblink https://software.intel.com/en-us/android/blogs/2013/12/06/building-ffmpeg-for-android-on-x86. When I try to build my project, I encountered a three errors. I have been trying to rectify them from the past one week, I have tried all possible methods with no results.

  jni/jniplayer/jniplayer.cpp:1244 : error : undefined reference to 'sws_freeContext'
  jni/jniplayer/jniplayer.cpp:1384 : error : undefined reference to 'sws_scale'
  jni/jniplayer/jniplayer.cpp:1371 : error : undefined reference to 'sws_getContext'

  I have used arm libraries previously to build my Android arm project that compiled with no problems. Maybe, I am missing a few steps with x86. As all the above errors are generated only with x86.

  I suppose that the issue resides with the enabling of the macro for x86 platform.

  #if ARCH_ARM
  
  #define USE_SWSCALE 0
  
  #else
  
  #define USE_SWSCALE 1
  
  #endif

  Only when USE_SWSCALE is enabled, functions such as sws_getcontext get enabled in ffmpeg.

  Have someone encountered such errors before. Kindly, please offer me some help with this issue. Thanks in advance for any answers.

• Posthoc connect FFMPEG to opencv-python binary for Google Cloud Dataflow job

  16 juillet 2017, par bw4sz

  I would like to run some video processing jobs on linux based compute engines on Google Cloud DataFlow. Cloud DataFlow requires you to build a setup.py file, or supply dependencies in a requirements.txt.

  https://cloud.google.com/dataflow/pipelines/dependencies-python

  My video process requires opencv in python with FFMPEG support. I would like to avoid building opencv from source, as this takes nearly 35 minutes for each worker to git clone/make/make install.

  There is a linux python binary .whl that works great. But its specifically compiled without FFMPEG.

  From https://pypi.python.org/pypi/opencv-python

  "IMPORTANT NOTE

  MacOS and Linux wheels have currently some limitations :

  video related functionality is not supported (not compiled with FFmpeg)"

  Is it possible to post-hoc connect FFMPEG to the binary ? That is download FFMPEG and its libraries separately and still read video ? I know this is contrived, but are are there any options here besides building opencv from source for every new worker ?