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• How to extract a video snippet from a video file that is being written in by ffmpeg in realtime

  26 février 2015, par alex.b

  At the moment i am recording a LIVE stream video from youtube with youtube-dl (https://github.com/rg3/youtube-dl)

  The command i use for this :

  youtube-dl --id -f 92 https://www.youtube.com/watch?v=VYlQJbsVs48

  92 is a format code that i got after executing a command to get the formats, that gave me this list :

  format code  extension  resolution note
  
  140          m4a        audio only DASH audio  144k , m4a_dash container, aac  @128k (48000Hz)
  
  141          m4a        audio only DASH audio  272k , m4a_dash container, aac  @256k (48000Hz)
  
  160          mp4        256x144    DASH video  124k , 15fps, video only
  
  133          mp4        426x240    DASH video  258k , 30fps, video only
  
  134          mp4        640x360    DASH video  616k , 30fps, video only
  
  135          mp4        854x480    DASH video 1116k , 30fps, video only
  
  136          mp4        1280x720   DASH video 2216k , 30fps, video only
  
  137          mp4        1920x1080  DASH video 4141k , 30fps, video only
  
  151          mp4        72p        HLS
  
  132          mp4        240p       HLS
  
  92           mp4        240p       HLS
  
  93           mp4        360p       HLS
  
  94           mp4        480p       HLS
  
  95           mp4        720p       HLS
  
  96           mp4        1080p      HLS  (best)

  This is creating a file called VYlQJbsVs48.mp4.part that gets bigger and bigger of course.

  Is there a way to extract a video snippet from that live stream or form the part file ? Or maybe there is a better way of doing this ?

  What i have noticed is that if i force quit iTerm2 while youtube-dl is running the .part file it creates wont contain any index information (something to do with an moov atom not being present in the mp4 file - which is the information about the number of frames and other things - metadata i think), so it makes me think i cannot extract from the file.

  Maybe if there would be a way that youtube-dl can write the index information at all times or maybe another way that i can record the live stream and get video snippets while its recording.

  I forgot to mention i am doing this on OSX Yosemite. I have FFMPEG installed with homebrew and youtoube-dl

  I am more than happy to try stuff on UBUNTU if there is a solution.

  Any help would be greatly appreciated.

  Thank you.

  Alex

• Changing Parameters in FFmpeg while encoding ?

  27 février 2019, par Trycoder

  I am using FFmpeg to create MPEG dash segments from my camera and playing it using Shaka Player. But I want to change the segment size (For example 2 seconds to 1 second) without creating a new process and without exiting the current process. Is there a change to change the parameter value in FFmpeg while the process is still running ?

  ffmpeg -f avfoundation -video_size 1280x720  -rtbufsize 100M  -r 30  -i 0 -qscale 100 -g 1 -vcodec libx264 seg_duration 1 -f dash -use_timeline 0 -use_template 0 -single_file 0 ffmpeg.mpd

  This is the command where I want to change the segment_duration to 2, without exiting the current process.

  ie.

  ffmpeg -f avfoundation -video_size 1280x720  -rtbufsize 100M  -r 30  -i 0 -qscale 100 -g 1 -vcodec libx264 -seg_duration 2 -f dash -use_timeline 0 -use_template 0 -single_file 0 ffmpeg.mpd

  Or is there any other MPEG DASH Encoder for this use case ?

• FFMPEG : Timestamps are unset in a packet for stream 0.Non-monotonous DTS in output stream 0:0

  22 février 2018, par Lily Priya

  I’m using FFMPEG to connect an RTSP and create video files on the fly that can be viewed in a mpeg-dash compatible browser using HTML5 video element and dash.js

  ffmpeg to connect to your ip camera

  ffmpeg -i rtsp ://194.168.26.234:554 -r 64k -an -c:v copy -b:v 2000k
  -fflags nobuffer -f dash -window_size 4 -extra_window_size 0 -min_seg_duration 2000000 -remove_at_exit 1 ..\www\manifest.mpd

  When I Run the command,it streaming properly but in the middle I’m getting error on Timestamps and also in Non-monotonous DTS. And also it was 3-15 sec delay Here My error,

  [dash @ 000000d62f752f20] Timestamps are unset in a packet for stream
  0. This is deprecated and will stop working in the future. Fix your code to set the timest amps properly
  [dash @ 000000d62f752f20] Non-monotonous DTS in output stream 0:0 ;
  previous : 0, current : 0 ;changing to 1. This may result in incorrect
  timestamps in the output file.

  [mp4 @ 000000d6302824e0] Application provided duration : -64 /
  timestamp : 1275009 is out of range for mov/mp4 format

  frame= 513 fps= 34 q=-1.0 size=N/A time=00:00:20.40 bitrate=N/A
  speed=1.35x frame= 527 fps= 34 q=-1.0 size=N/A time=00:00:20.96
  bitrate=N/A speed=1.34x

  [dash @ 000000d62f752f20] Non-monotonous DTS in output stream 0:0 ; previous : 134 1505, current : 1341505 ; changing to 1341506. This may result in incorrect timest amps in the output file.