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• ffmpeg : concatenating mp4 files. Video freezes for few seconds on first frame on output mp4

  20 février 2020, par suste88

  I created several MP4 files using ffmpeg. All of the videos have same settings and codec. Only difference is frames per second and duration. I then concatenated the videos using command below.

   ffmpeg -f concat myList.txt -c copy output.mp4

  I notice that when launching/opening the output.mp4 file in windows media player, it stops/freezes on the first frame of the video for about three four seconds and then starts playing, rest of the videos has correct fps and runs smoothly. Has anyone encountered this issue. I would like the video to start as soon as it is launched. Any suggestions to mitigate this issue ?

  Update : So far, I have found that the video length is exactly what I expect it to be.

  ffprobe -i output.mp4

  When i ffplay the video, it runs smoothly, but when I use windows media player, it gets stuck in first frame for about 4-5 seconds then plays smoothly. So I am going to assume that this issue is related to media players (buffers/loading before playing). Can’t be sure though.

• FFMPEG & YouTube Live - "Bad Video Settings" - Please use a keyframe frequency of four seconds or less

  28 janvier 2020, par John Doe

  Trying to live stream to YouTube and from my perspective, everything seems to be working fine. However YouTube keeps giving me the following message :

  Bad Video Settings

  Please use a keyframe frequency of four seconds or less. Currently, keyframes are not being sent often enough, which will cause buffering. The current keyframe frequency is 8.4 seconds. Note that ingestion errors can cause incorrect GOP (group of pictures) sizes.

  I’ve dug around for hours and so far nothing seems to be making any difference. I added -g 60 and as I didn’t fully understand I also tried adding -g 2 but neither worked. Here is the command I’m currently using :

  ffmpeg -re -f concat -safe 0 -i "concat.txt" -c copy -preset veryfast -maxrate 1200k -bufsize 2400k -framerate 30 -g 60 -f flv rtmp://a.rtmp.youtube.com/live2/XXXX-XXXX-XXXX-XXXX

• from_file function of pydub's audiosegment is only reading about 5 seconds of audio every time

  17 janvier 2020, par Johan Dingler

  I’m calling from_file on a .webm audio file in order to convert it to .mp3.
  The mp3 is successfully generated, however it’s always a bit short of 5 seconds long (between 4600-4800 ms everytime). I have no idea what is going on. After reading the original .webm into the audiosegment, I print it’s length and it’s 4600-4800. This is my code :

  pydub.AudioSegment.converter = '/opt/bin/ffmpeg'
  
  audioSegment = pydub.AudioSegment.from_file('/tmp/audioFile.{}'.format(event['audioFormat']), format=event['audioFormat'], codec=event['codec'])
  
  print('length of audio ', len(audioSegment))
  
  audioSegment.export('/tmp/output.mp3')

  Any ideas what might be going on ?