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• Color Correcting MP4/Webm videos

  2 octobre 2014, par sottenad

  I have a large video that features some animations too complex/long for other methods of embedding (gif, png sequence, etc.) and we are running into an issue with the colors in the video. Essentially we are including the background of the web page as part of the video in order to prevent the appearance of any edges on the video when it plays. We are trying to get the gradient background on the video to match that on the webpage, but the colors are WAY off.

  Are there any recommendations on how to color correct an MP4 video ? Or any html5-safe ways to do video with an alpha channel ?

• 2 source videos in FFMPEG... how to map audio ?

  21 juin 2012, par dcoffey3296

  i am currently placing 2 videos side by side in FFMPEG. Here is the command :

  ffmpeg -i input.mov -vf "[in] scale=1280:720, pad=2*1280:720 [left]; movie=right.mov, scale=1280:720 [right]; [left][right]  overlay=1280:0 [out]" -b:v 1000k -vcodec libx264 -an sidebyside.mp4

  I now need to manage the audio. I keep trying to specify :

  -acodec libfaac -ac 2 -map 0:1 -map 0:2

  to take the 2 audio channels from the first input and use them. I keep getting the error :

  [aformat @ 0x7febf2e01fc0] auto-inserting filter 'auto-inserted resampler 0' between the filter 'src' and the filter 'aformat'
  
      [aresample @ 0x7febf2e02180] [SWR @ 0x7febf40dd000] Input channel layout isnt supported
  
  Error opening filters!

  I'm looking for the best way to specify which video provides the audio ! Thanks for any advice !

  Here's the complete output :

  ffmpeg version 0.11.1 Copyright (c) 2000-2012 the FFmpeg developers
  
    built on Jun  9 2012 21:40:17 with clang 3.0 (tags/Apple/clang-211.10.1)
  
    configuration: --prefix= --enable-gpl --enable-version3 --enable-nonfree --enable-libx264 --enable-libxvid --enable-postproc --enable-swscale --enable-avfilter --enable-pthreads --enable-yasm --enable-libfaac --enable-libmp3lame --cc=clang --enable-libvorbis
  
    libavutil      51. 54.100 / 51. 54.100
  
    libavcodec     54. 23.100 / 54. 23.100
  
    libavformat    54.  6.100 / 54.  6.100
  
    libavdevice    54.  0.100 / 54.  0.100
  
    libavfilter     2. 77.100 /  2. 77.100
  
    libswscale      2.  1.100 /  2.  1.100
  
    libswresample   0. 15.100 /  0. 15.100
  
    libpostproc    52.  0.100 / 52.  0.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'left.mov':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 537199360
  
      compatible_brands: qt  
  
      creation_time   : 2012-06-19 21:13:20
  
    Duration: 00:02:28.81, start: 0.000000, bitrate: 36378 kb/s
  
      Stream #0:0(eng): Video: mpeg2video (Main) (xdvf / 0x66766478), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 35000 kb/s, 29.97 fps, 29.97 tbr, 2997 tbn, 59.94 tbc
  
      Metadata:
  
        creation_time   : 2012-06-19 21:13:20
  
        handler_name    : Apple Alias Data Handler
  
      Stream #0:1(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, 1 channels (FL), s16, 768 kb/s
  
      Metadata:
  
        creation_time   : 2012-06-19 21:13:20
  
        handler_name    : Apple Alias Data Handler
  
      Stream #0:2(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, 1 channels (FR), s16, 768 kb/s
  
      Metadata:
  
        creation_time   : 2012-06-19 21:13:20
  
        handler_name    : Apple Alias Data Handler
  
      Stream #0:3(eng): Data: none (tmcd / 0x64636D74)
  
      Metadata:
  
        creation_time   : 2012-06-19 21:13:20
  
        handler_name    : Apple Alias Data Handler
  
        timecode        : 02:20:28;08
  
  File 'output.mp4' already exists. Overwrite ? [y/N] y
  
  w:1920 h:1080 pixfmt:yuv420p tb:1/2997 sar:1/1 sws_param:flags=2
  
  [buffersink @ 0x7febf2c18c80] No opaque field provided
  
  [movie @ 0x7febf2c191c0] seek_point:0 format_name:(null) file_name:/Users/danielpcoffey/Desktop/tommy.mov stream_index:0
  
  [scale @ 0x7febf2c19320] w:1920 h:1080 fmt:yuv420p sar:1/1 -> w:1280 h:720 fmt:yuv420p sar:1/1 flags:0x4
  
  [pad @ 0x7febf2c19800] w:1280 h:720 -> w:2560 h:720 x:0 y:0 color:0x000000FF
  
  [scale @ 0x7febf2c1ca40] w:1920 h:1080 fmt:yuv420p sar:1/1 -> w:1280 h:720 fmt:yuva420p sar:1/1 flags:0x4
  
  [overlay @ 0x7febf2c1ce20] main w:2560 h:720 fmt:yuv420p overlay x:1280 y:0 w:1280 h:720 fmt:yuva420p
  
  [overlay @ 0x7febf2c1ce20] main_tb:1/2997 overlay_tb:1/2997 -> tb:1/2997 exact:1
  
  [aformat @ 0x7febf2e01fc0] auto-inserting filter 'auto-inserted resampler 0' between the filter 'src' and the filter 'aformat'
  
  [aresample @ 0x7febf2e02180] [SWR @ 0x7febf40dd000] Input channel layout isnt supported
  
  Error opening filters!

• What can be the substitute for SDL to direct ffmpeg decoded videos to screen in IOS ?

  18 octobre 2012, par jAckOdE

  I making a iOS video player using ffmpeg, the flow likes this :

  Video File---> [FFMPEG Decoder] —> decoded frames —> [a media director] —> /iphone screen (full and partial)/

  A media director will handle the tasks of rendering decoded video frames to iOS ui (UIView, UIWindow etc), outputting audio samples to iOS speaker, and threads management.

  SDL is one of those libs, but SDL is mainly made for game making purpose and seem to be not really mature for iOS.

  What can be the substitute for SDL ?