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• Why review compositing work in MJPEG videos rather than (say) H.264 ?

  6 juin 2016, par d3vid

  I have received a request to encode DPX files to MOV/MJPEG rather than MOV/H.264 (which ffmpeg picks by default if you convert to output.mov). These is to review compositing renders (in motion), so color accuracy is critical.

  Comparing a sample "ideal" MOV to the current (H.264) output I can see :

  • resolution : the same
  • ColorSpace/Primaries : Rec609 (SD) versus Rec709 (HD)
  • YUV : 4:2:0 versus 4:4:4
  • filesize : smaller

  The ffmpeg default seems to be better quality and result in a smaller filesize. Is there something I’m missing ?

• How to concatenate two videos w. ffmpeg — documented code not working

  2 mars 2014, par Jim Miller

  I'm trying to concatenate two videos with ffmpeg. Nothing fancy ; I just want one video that consists of video A immediately followed by video B.

  I've tried the code from How to concatenate (join, merge) media files on a freshly built and otherwise-working-fine install of ffmpeg 1.2.1 on Fedora 17, but the following error message appears :

  $ ffmpeg -i video_a.mov -i video_b.mov -filter_complex '[0:0] [0:1] [1:0] [1:1] concat=n=2:v=1:a=1 [v] [a]' -map '[v]' -map '[a]' output.mp4
  
  
  
  ffmpeg version N-54271-g7f866c1 Copyright (c) 2000-2013 the FFmpeg developers
  
    built on Jun 29 2013 11:05:42 with gcc 4.7.2 (GCC) 20120921 (Red Hat 4.7.2-2)
  
    configuration: --enable-gpl --enable-nonfree --enable-pthreads --enable-libx264 --enable-libfaac --extra-cflags=-I/usr/local/include --extra-ldflags=-L/usr/local/lib
  
    libavutil      52. 37.101 / 52. 37.101
  
    libavcodec     55. 17.100 / 55. 17.100
  
    libavformat    55. 10.100 / 55. 10.100
  
    libavdevice    55.  2.100 / 55.  2.100
  
    libavfilter     3. 77.101 /  3. 77.101
  
    libswscale      2.  3.100 /  2.  3.100
  
    libswresample   0. 17.102 /  0. 17.102
  
    libpostproc    52.  3.100 / 52.  3.100
  
  
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'v1221-MTQxMzcyNTIxODU2.mov':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 0
  
      compatible_brands: qt  
  
      creation_time   : 2013-03-28 20:34:59
  
      encoder         : Mac OS X v10.8.3 (CMA 914, CM 926.87, x86_64)
  
      encoder-eng     : Mac OS X v10.8.3 (CMA 914, CM 926.87, x86_64)
  
    Duration: 00:00:05.34, start: 0.000000, bitrate: 15837 kb/s
  
      Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 221 kb/s
  
      Metadata:
  
        creation_time   : 2013-03-28 20:34:59
  
        handler_name    : Core Media Data Handler
  
      Stream #0:1(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 15512 kb/s, 29.81 fps, 30 tbr, 600 tbn, 1200 tbc
  
      Metadata:
  
        creation_time   : 2013-03-28 20:34:59
  
        handler_name    : Core Media Data Handler
  
  
  
  Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'v1224-MTQxMzcyNTIxODg5.mov':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 0
  
      compatible_brands: qt  
  
      creation_time   : 2013-03-28 20:36:28
  
      encoder         : Mac OS X v10.8.3 (CMA 914, CM 926.87, x86_64)
  
      encoder-eng     : Mac OS X v10.8.3 (CMA 914, CM 926.87, x86_64)
  
    Duration: 00:00:04.13, start: 0.000000, bitrate: 15689 kb/s
  
      Stream #1:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 221 kb/s
  
      Metadata:
  
        creation_time   : 2013-03-28 20:36:28
  
        handler_name    : Core Media Data Handler
  
      Stream #1:1(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 15446 kb/s, 29.79 fps, 30 tbr, 600 tbn, 1200 tbc
  
      Metadata:
  
        creation_time   : 2013-03-28 20:36:28
  
        handler_name    : Core Media Data Handler
  
  
  
  Stream specifier ':0' in filtergraph description [0:0] [0:1] [1:0] [1:1] concat=n=2:v=1:a=1 [v] [a] matches no streams.

  A few other things to note :

  • The two videos I'm working with were shot with the same camera, so there shouldn't be any problems with aspect ratio or other gory video details.
  • I'm able to do other things with my ffmpeg installation, like convert one of those videos from .mov to .mp4 (yes, I had to recompile with faac...), which seems to vouch for both the ffmpeg and the video.
  • I've tried modifying the above invocation to produce a .mov file at the end, but I get the same error as before.
  • I've tried some stupid hacking tricks on the request above, like concatenating two copies of the same video, as well as some other invocations from other places around the web that involve filter_complex. Even on ones that were cited as working, I get the "matches no streams" message.

• FFmpeg development on Eclipse on Windows

  10 juillet 2013, par Juan Ayala

  The first thing I did was to refer to tutorial on FFmpeg site.

  I set up MSYS+MinGW64, I cloned all the relevant pre-requisites (i.e OpenSSL, x264, rtmpdump),
  I successfully cross-compiled them all. I ran the configure for FFmpeg, and I was able to cross-compile that as well. And my statically linked ffmpeg.exe works to my satisfaction.

  In Eclipse I was able to create a project, load up the source code, navigate it, make some changes, even compile and step-through debug. The problem I am having is with the Eclipse design-time error, and I think this is more of an Eclipse/C++ thing than FFmpeg.

  For example in ffmpeg.c I find this error "Field 'bitstream_filters' could not be resolved" at this line :

  AVBitStreamFilterContext *bsfc = output_streams[i]->bitstream_filters;

  that output_streams is of type

  OutputStream **output_streams

  and when I try to open the declaration for OutputStream Eclipse gives me the option of two locations. Obviously Eclipse is not sure which of these declarations it is, hence the "could not be resolved" error. OutputStream is defined in the following 2 files

  • ffmpeg.h
  • libavformat/smoothstreamingenc.c

  (hmm nice to know FFmpeg can do smooth streaming...) but anyway the correct definition would of been the one in ffmpeg.h.

  So... the whole goal of getting the source into an IDE was so that I could enjoy the benefits of such things like intelisense. What can I do in Eclipse to set some sort of order or rule as to how it should resolve types in cases where the names clash like this ?