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• Does FFMPEG utilize CUDA or any other hardware acceleration yet ?

  25 janvier 2012, par Jason

  Simple question, but I am having trouble finding the answer.

  We are deciding on a transcoding engine (preferrably open source) and it looks to me that FFMPEG does not utilize hardware acceleration, but I am not sure.

  I believe ffmpeg uses libavcodec, the same library used in countless other products, such as Handbrake. I can't believe they don't support hardware acceleration, therefore, my question.

• Reading JPEG in ffmpeg

  23 octobre 2012, par Paul Lammertsma

  I'm trying to get ffmpeg to encode several individual JPEG images into a video on Android. I've successfully built it for Android (see the configuration string at the end of this post).

  I can encode an h.263+ video with randomly generated frame content, and ffmpeg otherwise appears to work well.

  A similar question suggests that the following code should be sufficient to load an image into an AvFrame :

  // Make sure we have the codecs
  
  av_register_all();
  
  
  
  AVFormatContext *pFormatCtx;
  
  int ret = av_open_input_file(&pFormatCtx, imageFileName, NULL, 0, NULL);
  
  
  
  if (ret != 0) {
  
      printf("Can't open image file '%s': code %d, %s",
  
          imageFileName, ret, strerror(AVERROR(ret)));
  
  }

  The above returns the correct absolute file path and error :

  Failed '/sdcard/DCIM/Camera/IMG083.jpg' : code -1094995529, Unknown error : 1094995529

  Incidentally, if I omit av_register_all(), it returns with error 2.

  I've compiled ffmpeg with the following arguments :

  ./configure —target-os=linux
  —prefix=$PREFIX
  —enable-cross-compile
  —extra-libs="-lgcc"
  —arch=arm
  —cc=$PREBUILT/bin/arm-linux-androideabi-gcc
  —cross-prefix=$PREBUILT/bin/arm-linux-androideabi-
  —nm=$PREBUILT/bin/arm-linux-androideabi-nm
  —sysroot=$PLATFORM
  —extra-cflags=" -O3 -fpic -DANDROID -DHAVE_SYS_UIO_H=1 -Dipv6mr_interface=ipv6mr_ifindex -fasm -Wno-psabi -fno-short-enums -fno-strict-aliasing -finline-limit=300 $OPTIMIZE_CFLAGS "
  —enable-shared
  —enable-static
  —extra-ldflags="-Wl,-rpath-link=$PLATFORM/usr/lib -L$PLATFORM/usr/lib -nostdlib -lc -lm -ldl -llog"
  —disable-everything
  —enable-demuxer=mov
  —enable-demuxer=h264
  —disable-ffplay
  —enable-protocol=file
  —enable-avformat
  —enable-avcodec
  —enable-decoder=mjpeg
  —enable-decoder=png
  —enable-parser=h264
  —enable-encoder=h263
  —enable-encoder=h263p
  —disable-network
  —enable-zlib
  —disable-avfilter
  —disable-avdevice

  Any suggestions would be most welcome !

• Getting artifacts when trying to read video stream from YouTube

  23 février 2012, par givi

  I'm trying to read the video frames from the RTSP stream that I get from YouTube. Here is the link for my test video :

  rtsp ://v8.cache5.c.youtube.com/CiILENy73wIaGQkJlrXMiAG8BxMYDSANFEgGUgZ2aWRlb3MM/0/0/0/video.3gp

  If I'm reading frames from the local file - everything is fine, but when read them from a stream I get nothing but lots of artifacts. I've googled around and found out that there might be a problem with UDP packets and switching to TCP may help but I really can't find where it is possible to change this.

  Here is the function for reading a frame :

  bool nextFrame(AVFormatContext *pFormatCtx, AVCodecContext *pCodecCtx, int videoStream, AVFrame *pFrame) {  AVPacket packet;
  
      int frameFinished = 0;
  
  
  
      while( !frameFinished && av_read_frame(pFormatCtx, &packet) >= 0 ) {
  
          // Is this a packet from the video stream?
  
          if( packet.stream_index == videoStream ) {
  
              // Decode video frame
  
              avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
  
          }
  
  
  
          // Free the packet that was allocated by av_read_frame
  
          av_free_packet(&packet);    
  
         }    
  
         return frameFinished!=0;  
  
  }

  I'm also getting lots of error messages in my log :

  [h263 @ 0x7804c00] warning: first frame is no keyframe
  
  [h263 @ 0x7804c00] illegal ac vlc code at 6x1
  
  [h263 @ 0x7804c00] Error at MB: 18
  
  [h263 @ 0x7804c00] concealing 99 DC, 99 AC, 99 MV errors
  
  [h263 @ 0x7804c00] I cbpy damaged at 10 4
  
  [h263 @ 0x7804c00] Error at MB: 58
  
  [h263 @ 0x7804c00] concealing 99 DC, 99 AC, 99 MV errors
  
  [h263 @ 0x7804c00] I cbpy damaged at 6 6
  
  [h263 @ 0x7804c00] Error at MB: 78
  
  [h263 @ 0x7804c00] concealing 76 DC, 76 AC, 76 MV errors
  
  [h263 @ 0x7804c00] I cbpy damaged at 5 5
  
  [h263 @ 0x7804c00] Error at MB: 65
  
  [h263 @ 0x7804c00] concealing 88 DC, 88 AC, 88 MV errors
  
  [h263 @ 0x7804c00] illegal ac vlc code at 7x5
  
  [h263 @ 0x7804c00] Error at MB: 67
  
  [h263 @ 0x7804c00] concealing 86 DC, 86 AC, 86 MV errors

  ...and so on

  edit : this is 99.9% a UDP-TCP problem. I've found this link :

  rtsp ://195.200.199.8/mpeg4/media.amp

  This is some test camera available online. It streams with artifacts. However if it has get parameter 'tcp' and if I use this

  rtsp ://195.200.199.8/mpeg4/media.amp ?tcp

  everything works without artifacts.

  So to correct my question : is there any way to force YouTube or ffmpeg to use TCP ?