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• How to split a 1 hour video .mp4 file into 5 seconds segments for Media Source Extension API

  15 avril 2018, par Harpreet Singh

  I’m designing a web media player with the Media Source Extension API. I really like the process of how dash.js distributes the media by having the original media split into number of small files and be played in the web. I have visited the source storage of the bbb_30fps at https://dash.akamaized.net/akamai/bbb_30fps. And I looked at the 720p video quality directory at https://dash.akamaized.net/akamai/bbb_30fps/bbb_30fps_1280x720_4000k and the audio directory at https://dash.akamaized.net/akamai/bbb_30fps/bbb_a64k. I saw that the original 10 min video has been split into small segments of 720p quality excluding the audio with the file type of .m4v and small segments of the audio excluding the video with the file type of m4a.

  I want to have my 1 hour .mp4 video split into 720p quality with separate segments of duration 5 seconds excluding the audio and with the file type of .m4v. I also want to split the audio into separate segments of 5 seconds excluding the video with the file type of .m4a. If someone can help me please comment below. Thanks

  So far I have visited http://www.instructables.com/id/Making-Your-Own-Simple-DASH-MPEG-Server-Windows-10/ but it want not able to help me with my needs. And I have tried number of other methods with MP4Box but I can’t get the result I want.

• mp3/aac trim precision issue

  27 janvier 2020, par Massimo Vantaggio

  Due to mp3/aac codec doesn’t support that level of trim precision so im unable to get rounded container duration (without this 6 ms) :

  ffprobe -v error -show_entries format=duration \
  
  >   -of default=noprint_wrappers=1:nokey=1 output_audio.mp4
  
  372.006000

  MP4box generation get 6 ms more for every cycle :

  [...]
  
  Next generation scheduled in 3895 ms (DASH time 412006 ms)
  
  [...]
  
  Next generation scheduled in 3895 ms (DASH time 414012 ms)

  My MP4box command :

  MP4Box -dash-live 2000 -subdur 4000 -bound -segment-timeline -no-cache -profile dashavc264:live -subsegs-per-sidx -1 -mpd-refresh 4 -time-shift 16 -min-buffer 2000 -url-template -insert-utc -bs-switching no -run-for 86400000 -dash-ctx ../../live/log.txt -out ../../live/manifest.mpd ../current/output_1080.mp4:bandwidth=4800000#video ../current/output_720.mp4:bandwidth=2400000#video ../current/output_360.mp4:bandwidth=800000#video ../current/output_audio.mp4:bandwidth=384000#audio

  after 50% of the advertised duration an error will occur (probably)

  I say probably because the time for testing it is very long so may ask if the mp4box command provide for a stable loop or if the error will occur, and if yes, it will occur, may ask an help to debug my command line on mp4box to avoid this issue ?

  Im sorry but trial and error it’s too long since every try is about 24 hours..

  Dash.js web based purpose.

  Thansk in advance !

• ffmpeg pause and resume live stream encode

  14 janvier 2021, par ayylmao

  I am trying to use ffmpeg to create a live stream from a video file, encoded on the fly, that can be paused and resumed (like what Plex does). Suspending the ffmpeg process pauses the encoding, but resuming it causes ffmpeg to try to catch up to where it would have been in the stream. I assume there is some kind of internal timestamp that ffmpeg is looking at to keep track of timing. I would like ffmpeg to continue encoding from where it left off.

  


  I am using the "-re" switch to read the file at it's native framerate. I have tried hls and dash formats ; as far as I can tell, they both behave the same. Segmenting the entire file beforehand is not an option, I would like to be able to stream using only temporary files created on the fly.

  


  Here are simplified commands I've been using.

  


  HLS :
ffmpeg -y -re -i "input.mkv" -movflags +frag_keyframe+empty_moov+faststart -f hls -hls_time 2 -hls_list_size 10 -hls_delete_threshold 1 -hls_flags split_by_time+delete_segments+second_level_segment_index -strftime playlist.m3u8

  


  DASH :
ffmpeg -re -i input.mkv" -f dash -seg_duration 2 -window_size 5 -extra_window_size 0 -remove_at_exit 1 playlist.m3u8