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• Re-encode video stream only with ffmpeg (and with all audio streams)

  25 septembre 2016, par razr

  I’m looking for a way to re-encode the video stream of a movie only and keep all other streams as they are using ffmpeg or more specific streamio/streamio-ffmpeg (Github - StreamIO-FFMPEG).

  I already tried various combinations of -map 0 or -map a:0 -map s:0, but in all combinations I tried, either nothing is encoded at all, or not all other streams are copied to the new file. In most cases there is only one audio stream after encoding, when there were two before, and sometimes the subtitle streams are lost, too. Also most times the info what language the streams are in gets lost.

  So when I have a movie file (mkv) with the following streams :

  0: video [H.264, 1080p]
  
  1: audio [english, mp3]
  
  2: audio [french, mp3]
  
  3: subtitle [english (forced)]
  
  4: subtitle [english]

  What should the ffmpeg parameters be, if I want to encode the video file to H.265 and 720p and keep all other streams as they are ?

  What should the parameters be, if I additionally want to encode the audio streams as AAC ?

  Thanks in advance !

• ffmpeg : Missing subtitles on iPod

  7 septembre 2016, par forthrin

  I generating a playable video on a 3rd generation iPod Nano using the following command line, but I’m having certain challenges related to subtitles, stability and metadata.

  ffmpeg -y -i in.mkv -i in.srt -profile:v baseline -level 3 -refs 6 -ar 44100 -ac 2 -ab 128k
  
  -vf "scale=640:-1,pad=iw:480:0:(oh-ih)/2" -map 0:0 -map 0:1 -map 1:0 -map_metadata -1
  
  -movflags +faststart -scodec mov_text -metadata:s:s:0 language=eng out.mp4

  1. Subtitles won’t show. I tried both iPod settings "Subtitles On" and "Captions On". iPod software is latest 1.1.3. Subtitles show with OS X QuickTime after I change from "Auto" to "English" in the subtitle menu. Is there an ffmpeg flag to make subtitles display on the iPod ?

  2. The video player exits after 11-12 minutes for many of the converted videos. Restricting the bitrate -b:v 600k -bufsize 600k did not help. Any advice how to circumvent this ?

  3. Lastly, how can I make the video show under the "TV show" menu on the iPod ? Couldn’t find any help searching for "ffmpeg metadata tv". Or is this an internal iTunes feature ?

• FFmpeg. avcodec_find_encoder(AV_CODEC_ID_H264) return false

  14 juillet 2016, par Иван Чванов

  The problem : I can not connect the h264 codec for encoding and decoding of frames.

  ---

  Description :

  I downloaded from here ffmpeg library https://ffmpeg.zeranoe.com/builds/, version dev.

  Connect it to your project QT :

  extern "C"
  
  {
  
      #include 
  
      #include 
  
      #include 
  
      #include 
  
      #include 
  
  }
  
      
  
  #pragma comment (lib, "avcodec.lib")
  
  #pragma comment (lib, "avformat.lib")
  
  #pragma comment (lib, "swscale.lib")
  
  #pragma comment (lib, "avutil.lib")

  Next prescribe av_register_all(); to include all codecs.

  Next, call the function : avcodec_find_encoder(AV_CODEC_ID_H264), returns false.

  In the ReadMe file, the library said that it was collected with —enable-libx264 and —enable-gpl compile the keys including h264 codec that is supposed to be.

  If the call : avcodec_find_encoder(AV_CODEC_ID_MPEG1VIDEO), it returns an object AVCodec, as it should.

  I use the MinGW compiler. OC Windows 7.

  How can I resolve or work around the problem ? Compile the library itself has not yet obtained. I understand you to connect sources and "poking" them, that too is meaningless.

  ---

  ** Once again, I will describe my problem : **

  I need to encode the codec h264 (can VP9) individual frames in one program, and then decode them in another program. You can use other libraries. The language C ++. It is necessary to use interframe compression codec, rather than simply pressed apart frames.

  Sorry for my english.

  Ideas. Advice. Suggestions.