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• rtpdec : Always check if we have the next packet queued

  14 janvier 2013, par Martin Storsjö

  rtpdec : Always check if we have the next packet queued
  It doesn’t matter what the actual reason for not returning
  
  an AVPacket was - if we didn’t return any packet and we have
  
  the next one queued, parse it immediately. (rtp_parse_queued_packet
  
  always consumes a queued packet if one exists, so there’s no risk
  
  for infinite loops.)
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DBH] libavformat/rtpdec.c

• How to speed up ffmpeg video conversions [closed]

  24 janvier 2013, par PIKP

  I need to extract the audio as a MP3 file from a given video file. I have selected "ffmpeg" for audio extraction process. with the use of following arguments I have managed to extract the audio as a MP3. this work very well. but it takes about "2 minutes" to extract the audio from "21 minutes" long video file.

  ffmpeg -i source_video.avi -vn -ar 44100 -ac 2 -ab 128k -f mp3 sound.mp3

  for my purpose "2 minutes" for "21 minutes" is a long time. I need to speed up this as much as possible.

  could someone please tell me what are the factors that control the conversion speed ?

  currently I'm using a SATA hard disk with 7500rmp, will it speed up the conversion process if I upgrade my hard disk to SSD ?

  Thank you !

• How to concat videos that have different colour spaces ?

  17 avril 2023, par Ham789

  I writing a Python program that uses subprocess to automate ffmpeg. The program concatenates many videos together with the concat filter. The problem I have is that the colour of some of the videos is very washed out in the final output. I believe this is because the videos have different colour spaces. Some are B.709 and some are B.2020. The B.2020 videos are washed out.

  


  I have tried converting the B.2020 videos to B.709 before concatenating by using the following command on each video but the outputs are still washed out :

  


  ffmpeg -i input.mov -vf colorspace=all=bt709:iall=bt2020:fast=1 output.mov


  


  It wasn't clear to me which way round the arguments should go so I also tried switching the bt2020 and bt709 terms but they still look washed out but with more saturation.

  


  Is this the right approach ? Am I missing some other arguments in order to convert the B.2020 videos to B.709 while preserving their colour ?

  


  I have attached a side by side of the original and converted video.

  


  The metadata of the videos I am trying to concat are :

  


  Video 1

  


  

  • color_range=tv

  


  • color_space=bt709

  


  • color_transfer=bt709

  


  • color_primaries=bt709

  


  


  Video 2

  


  

  • color_range=tv

  


  • color_space=bt2020nc

  


  • color_transfer=arib-std-b67

  


  • color_primaries=bt2020