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• Video playing, how to play a video back a a rapid rate at random timestamp locations

  10 avril 2020, par Zarc Rowden

  Note : this is a mildly general question that is looking more for pointers in the right direction and not exactly requiring a concise coded answer. I appreciate any and all input, thank you for lending your brain power to me for this moment :)

  



  I have a script that receives midi messages in real time and triggers playback of a single video on various timestamps that are changed/selected regularly and randomly by a user. Currently this is working in the browser, however, I've realized that there is some noticeable latency between (i'm guessing the cause here so please correct me) the moment a request to play a video at a specific time is made(note : the video is not being requested over the wire, this action does not take place until a JS Blob Url is loaded into the player) and the moment where that request is fulfilled and delivered from storage to pixels on the screen.

  



  My question is : Is it reasonable to assume that there is a tool out there, that given the correct video format and optimizations both in the code and in the file that could load an entire, say : 1 gb video into memory and play it back at random timestamps every 60 milliseconds at completely random, constantly changing timestamps.

  



  If you're now all the way down here... Thanks for reading this far, or scanning ! Please let me know if this question makes any sense / could be improved, I'm happy to clarify further.

  


• Files created with a direct stream copy using FFmpeg's libavformat API play back too fast at 3600 fps

  2 octobre 2013, par Chris Ballinger

  I am working on a libavformat API wrapper that converts MP4 files with H.264 and AAC to MPEG-TS segments suitable for streaming. I am just doing a simple stream copy without re-encoding, but the files I produce play the video back at 3600 fps instead of 24 fps.

  Here are some outputs from ffprobe https://gist.github.com/chrisballinger/6733678, the broken file is below :

  r_frame_rate=1/1
  
  avg_frame_rate=0/0
  
  time_base=1/90000
  
  start_pts=0
  
  start_time=0.000000
  
  duration_ts=2999
  
  duration=0.033322

  The same input file manually sent through ffmpeg has proper timestamp information :

  r_frame_rate=24/1
  
  avg_frame_rate=0/0
  
  time_base=1/90000
  
  start_pts=126000
  
  start_time=1.400000
  
  duration_ts=449850
  
  duration=4.998333

  I believe the problem lies somewhere in my setup of libavformat here : https://github.com/OpenWatch/FFmpegWrapper/blob/master/FFmpegWrapper/FFmpegWrapper.m#L349 where I repurposed a bunch of code from ffmpeg.c that was required for the direct stream copy.

  Since 3600 seems like a "magic number" (60*60), it could be as simple as me not setting the time scale properly, but I can't figure out where my code diverges from ffmpeg/avconv itself.

  Similar question here, but I don't think they got as far as I did : Muxing a H.264 Annex B & AAC stream using libavformat with vcopy/acopy

• Revision 6c2035744a : Merge "Nextgen branch cleanup : add back some SVC functions" into nextgen

  9 juillet 2015, par Yunqing Wang

  Merge "Nextgen branch cleanup : add back some SVC functions" into nextgen