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• ffmpeg : Infinite amount of filters/crossfading dynamic playlist

  30 juillet 2019, par MaPePeR

  I want to use ffmpeg to play a dynamic playlist infinitely. The idea is, that an external command/script is executed to request the path to the next file (using the predicted start-time of the file as an argument) and continue playing files infinitely.

  From the answer to "Using FFMPEG to stream continuously videos files to a RTMP server" i learned, that i need to write a custom demuxer, that is similar to the concat demuxer. The problem arises from the fact, that i want to crossfade between the audio files and from my understanding of the demuxer i would have to implement that functionality into the demuxer itself to be able to do it, because a demuxer can only produce one (or a finite number) audio output stream and you need two to use the acrossfade-filter.

  So i would have to set up the filter graph like this :

  file1 --------------------------------*-->| cross | ---->more filters ---> Output
  
  file2 -----------------*-->| cross |----->| fade  |
  
  file3 --*-->| cross |----->| fade  |
  
        ... ->| fade  |

  Using an infinite number of crossfade-filters.

  Also i would really like to pre-filter(*, e.g. silenceremove) the audio files before cross-fading, which makes it even more complicated and the "implement everything in the demuxer"-approach even worse.

  My current solution would be to implement a custom demuxer that alternates between two output streams and does the prefiltering internally as well as an input-alternating crossfade filter like this :

  files -> | alternating |----->| alternating | ----> more filters--->
  
           |   demuxer*  |----->|  crossfade  |

  The problem i see with this approach is that i would need to send multiple EOF-terminated files from the demuxer to the crossfade-filter and i don’t know if that is even possible/allowed when using the standard ffmpeg functions like ff_request_frame.

  Can you tell me if this approach is feasible or do you have a better solution to this problem or any idea that would make this easier ?

• FFmpeg scale and concat with dynamic height

  21 août 2018, par Praveen Tamil

  Hi below is the code I’m using to concat multiple images.

  ffmpeg -loop 1 -t 1 -i img1.jpeg -loop 1 -t 1 -i img2.jpeg -loop 1 -t 1 -i img3.jpeg 
  
  -loop 1 -t 1 -i img4.jpeg -filter_complex "
  
  [0:v]scale=640:480:force_original_aspect_ratio=decrease, pad=640:480:(ow-iw)/2:(oh-ih)/2[v0];
  
  [1:v]scale=640:480:force_original_aspect_ratio=decrease, pad=640:480:(ow-iw)/2:(oh-ih)/2[v1];
  
  [2:v]scale=640:480:force_original_aspect_ratio=decrease, pad=640:480:(ow-iw)/2:(oh-ih)/2[v2];
  
  [3:v]scale=640:480:force_original_aspect_ratio=decrease, pad=640:480:(ow-iw)/2:(oh-ih)/2[v3];
  
  [v0][v1][v2][v3]concat=n=4"  output.gif

  But I’m getting below issue

  

• os_support : Remove the dynamic loading of getaddrinfo from the fallback getaddrinfo

  31 mai 2017, par Martin Storsjö

  os_support : Remove the dynamic loading of getaddrinfo from the fallback getaddrinfo
  If we for some unexplicable reason didn’t pick up getaddrinfo
  
  at configure, the default, IPv4-only, fallback should be good enough.
  This effectively reverts 6023d84a2b7.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DBH] libavformat/os_support.c