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• What's the best way to clip a live HLS feed at a certain date/time ?

  23 mai 2016, par Ryan Detzel

  I can record the whole stream using ffmpeg but I only want to record a certain part, say starting at 10:00:30-04:00 and recording for 30 seconds. I can’t find a way to do this with ffmpeg directly so I’m thinking of using a script to watch the HLS feed and when that time comes (via EXT-X-PROGRAM-DATE-TIME) trigger ffpmeg to start recording for 30 seconds. Is there a better way to do this ?

• YouTube Live Broadcast silence detect

  12 mai 2020, par Markus

  I'm trying to monitor a YouTube live broadcast for silence to be able to restart ffmpeg broadcast. How would you achieve that without breaking the YouTube ToS ?

  



  I tried with the YouTube API, but health.status is only supported for Live streams but not for broadcast.

  



  I came up with the idea of youtube-dl, grabing the m3u8 and the run ffmpeg with silencedetect but now I'm somehow stuck.

  



  Get the formats

  



  youtube-dl --list-formats https://www.youtube.com/watch?v=BiHequcIiNw


  



  Get the m3u8 manifest

  



  youtube-dl -f 91 -g https://www.youtube.com/watch?v=BiHequcIiNw


  



  Run ffprobe

  



  ffprobe -v quiet -print_format json -show_streams https://manifest.googlevideo.com/api/manifest/hls_playlist/expire/1588936061/ei/Hem0Xp35EZLl1wLLhYaYCA/ip/2a02:1205:c6bb:4590:301f:6186:c624:f2ba/id/BiHequcIiNw.0/itag/91/source/yt_live_broadcast/requiressl/yes/ratebypass/yes/live/1/goi/160/sgoap/gir%3Dyes%3Bitag%3D139/sgovp/gir%3Dyes%3Bitag%3D160/hls_chunk_host/r3---sn-nfpnnjvh-9and.googlevideo.com/playlist_duration/30/manifest_duration/30/vprv/1/playlist_type/DVR/initcwndbps/13630/mh/GY/mm/44/mn/sn-nfpnnjvh-9and/ms/lva/mv/m/mvi/2/pl/48/dover/11/keepalive/yes/fexp/23882513/mt/1588914375/disable_polymer/true/sparams/expire,ei,ip,id,itag,source,requiressl,ratebypass,live,goi,sgoap,sgovp,playlist_duration,manifest_duration,vprv,playlist_type/sig/AOq0QJ8wRgIhALApv3H2YEE2GLTXIyRxw8Fu8espLgRThUfhi97DIS6-AiEAsT_4bwAfsihK6zsrKgaxMYTemlAr8BXnBTwuhwe3aAE%3D/lsparams/hls_chunk_host,initcwndbps,mh,mm,mn,ms,mv,mvi,pl/lsig/AG3C_xAwRQIgRG3c1ww23Jokzk6vfAfeZlhwEanWG_9GmwRip81v65cCIQDg1Y9pXWS4bUjpKpZ90c3icp4slmAzhQJPn2gqW0UOeQ%3D%3D/playlist/index.m3u8


  



  But I haven't found a difference in the json if the stream is up or down. Any hint how I could monitor the m3u8 if it's up or down ?

  


• Issue with MJPEG stream playback speed when encoding with FFmpeg

  6 janvier, par Arciiix

  I'm working with a MJPEG stream source

  


  Stream #0:0: Video: mjpeg (Baseline), yuvj420p(pc, bt470bg/unknown/unknown), 1280x720 [SAR 1:1 DAR 16:9], 25 tbr, 25 tbn

  


  I want to capture this stream and save it to an MP4 file using FFmpeg, but I am running into a weird issue.

  


  The only way it works fine is when I just copy the stream without reencoding and using wallclock as timestamps (cmd 1) :

  


  ffmpeg -use_wallclock_as_timestamps 1 -i "http://IP/video/1280x720" -c:v copy output_good.mp4


  


  However, when I try encoding the stream with libx264, the playback speed of the resulting video becomes slower than 100%, causing the video to gradually fall out of sync with real-time. This happens even when I use any encoding, also when I explicitly set the frame rate or vsync. For example, these commands fail :

  


  

  • CMD 2 : ffmpeg -i "http://IP/video/1280x720" -c:v libx264 -r 30 -preset fast output_bad1.mp4

  


  • CMD 3 : ffmpeg -use_wallclock_as_timestamps 1 -i "http://IP/video/1280x720" -c:v libx264 output.mp4

  


  


  https://www.youtube.com/watch?v=PF0fuCu7Xao

  


  As you can see in the comparison of the resulting videos, the playback gradually slows down with CMD 2 and CMD 3, while it's alright with CMD 1.

  


  What I've noticed is that on the FFmpeg stdout, when using encoding, the speed= and FPS= go up and up, e.g. to 31 FPS even though my source is technically at 25 FPS.

  


  What I've tried :

  


  

  • different encoding codecs (e.g. libvpx)

  


  • -re

  


  • preset ultrafast on encoding

  


  • vsync (fps_mode), both ctr and vfr

  


  • fps=30 filter

  


  


  Has anyone encountered a similar issue or know how to force FFmpeg to preserve the correct playback speed while encoding or enforcing a frame rate ? Thanks !