Recherche avancée

Sur d’autres sites (15417)

• fftools/ffmpeg : add support for multiview video

  10 août 2024, par Anton Khirnov

  fftools/ffmpeg : add support for multiview video
  This extends the syntax for specifying input streams in -map and complex
  
  filtergraph labels, to allow selecting a view by view ID, index, or
  
  position. The corresponding decoder is then set up to decode the
  
  appropriate view and send frames for that view to the correct
  
  filtergraph input(s).
  

  • [DH] doc/ffmpeg.texi
  • [DH] fftools/cmdutils.c
  • [DH] fftools/cmdutils.h
  • [DH] fftools/ffmpeg.h
  • [DH] fftools/ffmpeg_dec.c
  • [DH] fftools/ffmpeg_demux.c
  • [DH] fftools/ffmpeg_filter.c
  • [DH] fftools/ffmpeg_mux_init.c
  • [DH] fftools/ffmpeg_opt.c

• Crop Videos & Reduce Quickly on Mobile with or w/o FFMpeg (Flutter)

  11 mai 2021, par Haidar Hammoud

  Cropping, modifying quality, and other seemingly simple edits applied to videos using FFMpeg take between 30 to 60 seconds for a 15 second long video.

  


  Apps like Snapchat, Instagram, TikTok, WhatsApp, and Twitter are able to nearly instantly edit a video file with quality modifications, videos concatenated together, image overlays applied over every frame, and cropping. This is evident from the fact that videos can be viewed by the receivers within seconds of them being sent with all the modifications applied.

  


  Are there any reliable ways to achieve the same speeds (0.5 - 1.5 seconds) for video editing on mobile using Flutter ? FFMpeg has everything I need but just runs very slowly. Is there a way to speed it up ?

  


• Converting HLS video with fmp4 segments to image thumbnails via ffmpeg with start offset using fast seek

  19 octobre 2022, par hellerahum

  I'm having trouble with what I think should be a basic use case for ffmpeg. What I'd like to do is take an hls video in fmp4 and output 30s of images at 10fps, using "fast seek" to start at an offset well into the video. This works with an Apple sample using ts segments, but not with fmp4 segments.

  


  working sample (ts)

  


  ffmpeg -ss 00:00:05 -i https://devimages.apple.com.edgekey.net/iphone/samples/bipbop/bipbopall.m3u8 -t 30 -vf fps=10 hls_samples/img%03d.jpg


  


  broken sample (fmp4)

  


  ffmpeg -ss 00:00:05 -i https://devstreaming-cdn.apple.com/videos/streaming/examples/img_bipbop_adv_example_fmp4/master.m3u8 -t 30 -vf fps=10 hls_samples/img%03d.jpg


  


  The broken sample spits out errors like :

  


  [NULL @ 0x123e30d20] Invalid NAL unit size (-2003396084 > 1673).
[NULL @ 0x123e30d20] missing picture in access unit with size 1677


  


  and then finally :

  


  Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)
Conversion failed!


  


  When I re-encode the fmp4 video adding keyframes via -g 1 (still hls with fmp4) I'm then able to use the fast seek -ss flag before the -i , but i'd rather not do this in a 2-step process, and ideally would take the original hls/fmp4 manifest and output the thumbnails directly. Both samples work with the -ss flag after the input (slow seek) but I have some long (10+ hour) videos so that's not tenable. Anyone able to point me to what I'm doing wrong, or is it possible this is an issue with ffmpeg and its support for fmp4 ? I'm using ffmpeg v5.1.2 and have checked on both an M1 mac and Ubuntu system.