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• FFMPEG encoding with Intel Quick Sync, throwing "Access violation reading location "

  22 octobre 2015, par Paul Knopf

  I am using FFMPEG ffmpeg-20150610-git-913685f, from here.

  Using this library, I setup a application that captures UYVY frames from my frame grabber and encodes/muxes them to an MP4 file, using libx264. Works without issues.

  Now, I wanted to try to enabling Intel Quick Sync, so I changed the encoder.

  // old (libx264)
  
  //AVCodec* codec = avcodec_find_encoder(AV_CODEC_ID_H264);
  
  // new (Intel Quick Sync)
  
  AVCodec* codec = avcodec_find_encoder_by_name("h264_qsv");

  It finds the encoder ok. However, at the time of encoding a frame, I get the following exception.

  Unhandled exception at 0x000000005D4DDC9E (avcodec-56.dll) in
  MedXChangeDecLinkTest.exe : 0xC0000005 : Access violation reading
  location 0x0000000000000048.

  The exact API call is :

  avcodec_encode_video2(_internals->videoStream.stream->codec, &pkt, _internals->videoStream.frame, &got_packet);

  Is there more I need to do ? I noticed that there was a commit that added some additional pixel formats for QSV here. Do I have to do something differently, compared to how things were done with libx264 ?

  UPDATE : I also just realized that I am getting an error on the stdout.

  [h264_qsv @ 000000c7e6d8e680] Specified pixel format yuv420p is invalid or not supported

• Configuring install path : prefix=[PREFIX] not fully understood

  3 mai 2016, par whatshisface

  I think this is simply a general c++ question :

  I’m attempting to compile a local version of ffmpeg on Linux Fedora using the gnu c++ compiler. I have source code in a bunch of folders under :

  ~/<username>/Downloads/Code/ffmpeg_sources/
  
  </username>

  which is where I’m attempting to set the config flags to install the build to a target not under this tree but at a root level directory with local shared libraries :

  /usr/local/

  There is this following section near the beginning of the configuration file :

  Standard options:
  
  
  
   --prefix=PREFIX          install in PREFIX []
  
   --bindir=DIR             install binaries in DIR [PREFIX/bin]
  
   --datadir=DIR            install data files in DIR [PREFIX/share/ffmpeg]
  
   --docdir=DIR             install documentation in DIR [PREFIX/share/doc/ffmpeg]
  
   --libdir=DIR             install libs in DIR [PREFIX/lib]
  
   --shlibdir=DIR           install shared libs in DIR [PREFIX/lib]
  
   --incdir=DIR             install includes in DIR [PREFIX/include]
  
   --mandir=DIR             install man page in DIR [PREFIX/share/man]
  
   --enable-rpath           use rpath to allow installing libraries in paths
  
                            not part of the dynamic linker search path

  I may have completely misunderstood this, but I thought that setting a value like

  --prefix=/usr/local

  or

  --prefix=[/usr/local]

  might work, but it appears not to, as once the ./config, make&&make install is complete, it has done a bunch of stuff but there’s nothing installed at the target. There are a LOT of new executable files built in the source directory, so presumably the build is working but I’m simply specifying the paths incorrectly ? A part of the same problem is that it’s unclear whether, once I’ve set the

  --prefix=[PREFIX]

  correctly, I need to set all of the further

  --datadir, --libdir

  etc. or whether the first —prefix value is enough ?

  What is the above configuration syntax trying to show me ?

• Configuring install path : prefix=[PREFIX] not fully understood

  29 septembre 2019, par whatshisface

  I think this is simply a general c++ question :

  I’m attempting to compile a local version of ffmpeg on Linux Fedora using the gnu c++ compiler. I have source code in a bunch of folders under :

  ~/<username>/Downloads/Code/ffmpeg_sources/
  
  </username>

  which is where I’m attempting to set the config flags to install the build to a target not under this tree but at a root level directory with local shared libraries :

  /usr/local/

  There is this following section near the beginning of the configuration file :

  Standard options:
  
  
  
   --prefix=PREFIX          install in PREFIX []
  
   --bindir=DIR             install binaries in DIR [PREFIX/bin]
  
   --datadir=DIR            install data files in DIR [PREFIX/share/ffmpeg]
  
   --docdir=DIR             install documentation in DIR [PREFIX/share/doc/ffmpeg]
  
   --libdir=DIR             install libs in DIR [PREFIX/lib]
  
   --shlibdir=DIR           install shared libs in DIR [PREFIX/lib]
  
   --incdir=DIR             install includes in DIR [PREFIX/include]
  
   --mandir=DIR             install man page in DIR [PREFIX/share/man]
  
   --enable-rpath           use rpath to allow installing libraries in paths
  
                            not part of the dynamic linker search path

  I may have completely misunderstood this, but I thought that setting a value like

  --prefix=/usr/local

  or

  --prefix=[/usr/local]

  might work, but it appears not to, as once the ./config, make&&make install is complete, it has done a bunch of stuff but there’s nothing installed at the target. There are a LOT of new executable files built in the source directory, so presumably the build is working but I’m simply specifying the paths incorrectly ? A part of the same problem is that it’s unclear whether, once I’ve set the

  --prefix=[PREFIX]

  correctly, I need to set all of the further

  --datadir, --libdir

  etc. or whether the first —prefix value is enough ?

  What is the above configuration syntax trying to show me ?