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• Concatenating/Splicing overlapping video clips with ffmpeg

  16 décembre 2020, par Jimbo1987

  I'm trying to concatenate multiple short .mp4 video clips from a security camera. The camera records short clips, with a few seconds on either end of a timespan when motion is detected. For example, two minutes of video will often be broken up into four 35 second clips, with the first/last few seconds of each clip being duplicative of the last/first few seconds of the previous/next clip.

  


  I simply concatenate the clips together using the ffmpeg concat demuxer, as described here : How to concatenate two MP4 files using FFmpeg ?, with

  


  (echo file 'first file.mp4' & echo file 'second file.mp4' )>list.txt
ffmpeg -safe 0 -f concat -i list.txt -c copy output.mp4


  


  Or else I transcode them into intermediate MPEG-2 transport streams, which I can then concatenate with the file-level concat protocol, as described here : https://trac.ffmpeg.org/wiki/Concatenate#protocol, with

  


  ffmpeg -i "first file.mp4" -c copy -bsf:v h264_mp4toannexb -f mpegts intermediate1.ts
ffmpeg -i "second file.mp4" -c copy -bsf:v h264_mp4toannexb -f mpegts intermediate2.ts
ffmpeg -i "concat:intermediate1.ts|intermediate2.ts" -c copy -bsf:a aac_adtstoasc output.mp4


  


  But either way, the resulting video (output.mp4) jumps backward in time a few seconds every half-minute or so because of the duplicated frames.

  


  I want to throw out the duplicate frames, and tie the clips together based on timestamps to achieve smooth playback of the concatenated full-length video. I'd strongly prefer to do this on Windows with ffmpeg if possible. Surely this has been done before, right ? Are there timestamps in the .mp4 files that I can use to determine how much overlap there is, and then splice at the proper point-in-time ? And if so, how do I read them, how do I splice at an exact point in time, and how do I get around the KeyFrames issue if I can splice at the exact point in time ?

  


• ffplay too slow decoding h264 stream over RTP

  16 mars 2018, par Alejandro Aristizábal

  I need some help getting ffplay to receive and decode a Real Time stream encoded in h264.

  I’m trying to make a point-to-point stream between computer A receiving video frames from a Kinect and computer B running ffplay to show the livestream.

  These are the commands I’m running on both computers.

  Computer A (RPI 3)

  ffmpeg -f rawvideo -vcodec rawvideo -pix_fmt rgb24 -s 640x480 -i - -threads 4 -preset ultrafast -codec:v libx2 64 -an -f rtp rtp://192.168.0.100:2000

  This is what ffmpeg outputs :

  fps= 14 q=12.0 size=856kB time=00:00:05.56 bitrate=1261.4kbits/s speed=0.54x

  The out stream runs in between 10-20 frames. It’s not good, but I can work with that.

  Computer B

  ffplay -protocol_whitelist "file,udp,rtp" -probesize 32 -sync ext -i streaming.sdp

  streaming.sdp

  v=0
  
  0=- 0 0 IN IP4 127.0.0.1
  
  s=No Name
  
  c=IN IP4 192.168.0.100
  
  t=0 0
  
  a=tool:libavformat 57.56.100
  
  m=video 2000 RTP/AVP 96
  
  a=rtpmap:96 H264/90000
  
  a=fmtp:96 packetization-mode=1

  I’m getting the stream, but at about 0.0001fps which is crearly bad. My guess is I’m missing something on the ffplay command, since ffmpeg shows a more stable and fast stream, but I can’t seem to find what I’m missing.

  Thanks in advance

• Anomalie #3877 : Créer un nouvelle traduction perd la redirection (et les logos)

  16 décembre 2016, par b b

  Le bon projet...

  Après vérification, sur une 2.1.29 la traduction hérite bien de la redirection, mais pas du logo (donc pour ce point c’est une évolution).