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• How to prescale a frame using ffmpeg and H.265

  20 juillet 2017, par akw

  I want to decode video frames with the H.265 coded (AV_CODEC_ID_HEVC)
  I use the following code :

  AVCodec *hevcCodec = avcodec_find_decoder(AV_CODEC_ID_HEVC);
  
  AVCodecContext *avctx  = avcodec_alloc_context3(hevcCodec);
  
  avcodec_open2(avctx, hevcCodec, 0);
  
  AVFrame *frame = av_frame_alloc();
  
  AVPacket pkt;
  
  av_init_packet(&pkt);
  
  pkt.data = myDataPtr;
  
  pkt.size = myDataSize;
  
  int got_frame = 0;
  
  avcodec_send_packet(avctx, &pkt);
  
  if (avcodec_receive_frame(avctx, frame) >=0 ) {
  
          got_frame = 1;
  
          ...
  
  }

  This works fine, I got my YUV frame and can process it further (like converting to RGB or scaling, etc.)
  However, I would like to somehow tell the ffmpeg library, to scale the AVFrame while decoding (a scale factor of a power of 2 would be sufficient).
  I don’t want to scale after converting to RGB or use swscale or anything. I have to decode a lot of frames and need a smaller resolution.

  Is it possible to give the AVCodecContext some hints to scale the frames ?
  (I tried setting avctx.width and avctx.height, but this did not help)

• ppc : Clarify and extend the cpuid check

  10 mai 2015, par Luca Barbato

  ppc : Clarify and extend the cpuid check
  Add POWER entries.
  

  • [DBH] libavutil/ppc/cpu.c

• ffmpeg convert images to mp4 error

  31 mai 2013, par Ryan Saxe

  So I have a script that grabs a bunch of images from the web and then converts them into a movie. Yet I get a whole bunch of errors when I run it.

  First let me show what I am running and then I will post the error because it's huge :

  #for gif
  
  #call('convert -set delay 5 -loop 0 ' + folder + '*.jpg ' + name + '.gif', shell=True)
  
  #for mov
  
  #call('convert -quality 100 ' + folder + '*.jpg ' + name + '.mov', shell=True)
  
  #for organized movie
  
  call('ffmpeg -r 10 -b 1800 -i ' + folder + '%0' + str(size) + 'd.jpg ' + name + '.mp4', shell=True)

  So the commented out versions work fine, but I need to use the 3rd version ! Here is the response I get from ffmpeg :

  ffmpeg version 1.2 Copyright (c) 2000-2013 the FFmpeg developers
  
    built on Mar 31 2013 21:55:33 with Apple clang version 4.1 (tags/Apple/clang-421.11.66) (based on LLVM 3.1svn)
  
    configuration: --prefix=/opt/local --enable-swscale --enable-avfilter --enable-libmp3lame --enable-libvorbis --enable-libopus --enable-libtheora --enable-libschroedinger --enable-libopenjpeg --enable-libmodplug --enable-libvpx --enable-libspeex --enable-libfreetype --mandir=/opt/local/share/man --enable-shared --enable-pthreads --cc=/usr/bin/clang --arch=x86_64 --enable-yasm --enable-gpl --enable-postproc --enable-libx264 --enable-libxvid
  
    libavutil      52. 18.100 / 52. 18.100
  
    libavcodec     54. 92.100 / 54. 92.100
  
    libavformat    54. 63.104 / 54. 63.104
  
    libavdevice    54.  3.103 / 54.  3.103
  
    libavfilter     3. 42.103 /  3. 42.103
  
    libswscale      2.  2.100 /  2.  2.100
  
    libswresample   0. 17.102 /  0. 17.102
  
    libpostproc    52.  2.100 / 52.  2.100
  
  Please use -b:a or -b:v, -b is ambiguous
  
  [mjpeg @ 0x7f8cc402a800] [IMGUTILS @ 0x7fff5a680ae0] Picture size 10835x53928 is invalid
  
      Last message repeated 26 times
  
  [mjpeg @ 0x7f8cc402a800] Found EOI before any SOF, ignoring
  
  [mjpeg @ 0x7f8cc402a800] mjpeg: unsupported coding type (cf)
  
  [mjpeg @ 0x7f8cc402a800] mjpeg: unsupported coding type (c8)
  
  [mjpeg @ 0x7f8cc402a800] [IMGUTILS @ 0x7fff5a680ae0] Picture size 54310x53928 is invalid
  
  [mjpeg @ 0x7f8cc402a800] only 8 bits/component accepted
  
      Last message repeated 8 times
  
  [mjpeg @ 0x7f8cc402a800] mjpeg: unsupported coding type (c5)
  
  [mjpeg @ 0x7f8cc402a800] [IMGUTILS @ 0x7fff5a680ae0] Picture size 10835x53928 is invalid
  
      Last message repeated 12 times
  
  [mjpeg @ 0x7f8cc402a800] mjpeg: unsupported coding type (cf)
  
  [mjpeg @ 0x7f8cc402a800] only 8 bits/component accepted
  
  [mjpeg @ 0x7f8cc402a800] mjpeg: unsupported coding type (cf)
  
  [mjpeg @ 0x7f8cc402a800] only 8 bits/component accepted
  
  [mjpeg @ 0x7f8cc402a800] mjpeg: unsupported coding type (cf)
  
  [mjpeg @ 0x7f8cc402a800] only 8 bits/component accepted
  
  [image2 @ 0x7f8cc4029c00] decoding for stream 0 failed
  
  [image2 @ 0x7f8cc4029c00] Could not find codec parameters for stream 0 (Video: mjpeg): unspecified size
  
  Consider increasing the value for the 'analyzeduration' and 'probesize' options
  
  /Users/ryansaxe/Desktop/kaggle_parkinsons/MOVIES/%03d.jpg: could not find codec parameters

  Note :

  [mjpeg @ 0x7f8cc402a800] mjpeg: unsupported coding type (cf)
[mjpeg @ 0x7f8cc402a800] only 8 bits/component accepted

  repeated about 30 times, but i cut it out of the traceback because it was overwhelming.

  Question : What did I do wrong and how do I fix it ?

  Edit :

  I download the jpeg files using the urllib python library's urlretrieve. This is how I save them :

  for src,name in zip(urls,range(len(urls))):
  
      file_name = folder + str(name) + '.jpg'
  
      urlretrieve(src, file_name)