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• Concatenate chunk containg headers to another chunk in h264

  18 novembre 2014, par Ortixx

  I’m trying to extract thumbnails from a torrent stream by downloading the first couple of chunks to get the headers, another set of chunks from the middle and then concat them to have a single video file.

  For this I’m using nodejs but I’m having trouble with the concatenation part. Obviously the headers include the length of the video so if I simply concat another chunk to the end of the headers chunk, it won’t work.

  In other words, I have 2 chunks of a video file : The first one contains the headers and some material and the other one is fully composed of a video stream. I want to combine the two to form a single video file
  So my question is how can I make this work properly if at all ?

• Converting avi to mp4 (use ffmpeg library) is very slow [closed]

  7 décembre 2012, par yAnTar

  I have task - convert any video from user to mp4 format.
  I use command

  ffmpeg -i $file -vcodec libx264 -vpre ultrafast -bt 500k -acodec libfaac -ab 56k -ac 2 -s 480x320 $outputFileMp4

  I try to change options bitrate, dimensions, but spped of converting is slow - 3 mbytes convert arround 90 seconds.

  If i convert avi to flv - no problem.

  FFmpeg version 0.6.5, Copyright (c) 2000-2010 the FFmpeg developers
  
    built on Jan 29 2012 17:52:15 with gcc 4.4.5 20110214 (Red Hat 4.4.5-6)
  
    configuration: --prefix=/usr --libdir=/usr/lib64 --shlibdir=/usr/lib64 --mandir=/usr/share/man --incdir=/usr/include --disable-avisynth --extra-cflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic -fPIC' --enable-avfilter --enable-avfilter-lavf --enable-libdc1394 --enable-libdirac --enable-libfaac --enable-libfaad --enable-libfaadbin --enable-libgsm --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-librtmp --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libx264 --enable-gpl --enable-nonfree --enable-postproc --enable-pthreads --enable-shared --enable-swscale --enable-vdpau --enable-version3 --enable-x11grab
  
    libavutil     50.15. 1 / 50.15. 1
  
    libavcodec    52.72. 2 / 52.72. 2
  
    libavformat   52.64. 2 / 52.64. 2
  
    libavdevice   52. 2. 0 / 52. 2. 0
  
    libavfilter    1.19. 0 /  1.19. 0
  
    libswscale     0.11. 0 /  0.11. 0
  
    libpostproc   51. 2. 0 / 51. 2. 0
  
  Input #0, avi, from 'intro.avi':
  
    Duration: 00:07:48.53, start: 0.000000, bitrate: 244 kb/s
  
      Stream #0.0: Video: camtasia, bgr24, 800x600, 15 tbr, 15 tbn, 15 tbc
  
      Metadata:
  
        strn            : Camtasia Producer_render549ab1f.avi Video #1
  
      Stream #0.1: Audio: pcm_s16le, 12000 Hz, 1 channels, s16, 192 kb/s
  
      Metadata:
  
        strn            : Microsoft Waveform: Camtasia Producer_render549ab1f.wav
  
  [libx264 @ 0x1202e40]using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle SSE4.1 Cache64
  
  [libx264 @ 0x1202e40]profile Constrained Baseline, level 2.2
  
  [libx264 @ 0x1202e40]264 - core 107 - H.264/MPEG-4 AVC codec - Copyleft 2003-2010 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0x1:0 me=dia subme=0 psy=1 psy_rd=0.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=25 scenecut=0 intra_refresh=0 rc=abr mbtree=0 bitrate=200 ratetol=2.5 qcomp=0.60 qpmin=10 qpmax=51 qpstep=4 ip_ratio=1.41 aq=0
  
  Output #0, mp4, to 'test2.mp4':
  
    Metadata:
  
      encoder         : Lavf52.64.2
  
      Stream #0.0: Video: libx264, yuv420p, 640x480, q=10-51, 200 kb/s, 15 tbn, 15 tbc
  
      Metadata:
  
        strn            : Camtasia Producer_render549ab1f.avi Video #1
  
      Stream #0.1: Audio: libfaac, 12000 Hz, 2 channels, s16, 5 kb/s
  
      Metadata:
  
        strn            : Microsoft Waveform: Camtasia Producer_render549ab1f.wav
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
    Stream #0.1 -> #0.1

  and result of executing

  frame= 7028 fps= 52 q=10.0 Lsize=    2654kB time=468.31 bitrate=  46.4kbits/s
  
  video:1883kB audio:672kB global headers:0kB muxing overhead 3.876805%
  
  [libx264 @ 0xe1ee40]frame I:29    Avg QP:10.83  size: 25781
  
  [libx264 @ 0xe1ee40]frame P:6999  Avg QP:10.08  size:   169
  
  [libx264 @ 0xe1ee40]mb I  I16..4: 80.1%  0.0% 19.9%
  
  [libx264 @ 0xe1ee40]mb P  I16..4:  0.2%  0.0%  0.0%  P16..4:  0.2%  0.0%  0.0%  0.0%  0.0%    skip:99.6%
  
  [libx264 @ 0xe1ee40]final ratefactor: 5.71
  
  [libx264 @ 0xe1ee40]coded y,uvDC,uvAC intra: 37.1% 3.3% 3.1% inter: 0.1% 0.0% 0.0%
  
  [libx264 @ 0xe1ee40]i16 v,h,dc,p: 87% 12%  1%  0%
  
  [libx264 @ 0xe1ee40]i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 20% 23% 27%  8%  6%  3%  3%  2%  8%
  
  [libx264 @ 0xe1ee40]i8c dc,h,v,p: 94%  6%  0%  0%
  
  [libx264 @ 0xe1ee40]kb/s:32.91

• AVFrame to RGB - decoding artifacts

  10 janvier 2013, par Hyndrix

  I want to programmatically convert a mp4 video file (with h264 codec) to single RGB images. With the command line this looks like :

  ffmpeg -i test1080.mp4 -r 30 image-%3d.jpg

  Using this command produces a nice set of pictures. But when I try to programmatically do the same some images (probably B and P frames) look odd (e.g. have kind of distorted areas with difference information etc.). The reading and conversion code is as follow :

  AVFrame *frame = avcodec_alloc_frame();
  
  AVFrame *frameRGB = avcodec_alloc_frame();
  
  
  
  AVPacket packet;
  
  
  
  int buffer_size=avpicture_get_size(PIX_FMT_RGB24, m_codecCtx->width,
  
      m_codecCtx->height);
  
  uint8_t *buffer = new uint8_t[buffer_size];
  
  
  
  avpicture_fill((AVPicture *)frameRGB, buffer, PIX_FMT_RGB24,
  
      m_codecCtx->width, m_codecCtx->height);
  
  
  
  while (true)
  
  {
  
      // Read one packet into `packet`
  
      if (av_read_frame(m_formatCtx, &packet) < 0) {
  
          break;  // End of stream. Done decoding.
  
      }
  
  
  
      if (avcodec_decode_video(m_codecCtx, frame, &buffer_size, packet.data, packet.size) < 1) {
  
          break;  // Error in decoding
  
      }
  
  
  
      if (!buffer_size) {
  
          break;
  
      }
  
  
  
      // Convert
  
      img_convert((AVPicture *)frameRGB, PIX_FMT_RGB24, (AVPicture*)frame,
  
          m_codecCtx->pix_fmt, m_codecCtx->width, m_codecCtx->height);
  
  
  
      // RGB data is now available in frameRGB for further processing
  
  }

  How can I convert the video stream so that each final image shows all image data, so that information from B and P frames is included in all frames ?

  [EDIT :] A sample image showing the artifacts is here : http://imageshack.us/photo/my-images/201/sampleq.jpg/

  Regards,