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• FFMPEG problem when transcoding one after another

  10 juillet 2022, par Mike woods

  In server A, I have a loop to transcode video files one after another to MPEGTS format, And send them to server B. Server B receives the data and broadcast it to multiple clients. I'm using it to broadcast files like a TV channel. Something like this

  


  //Files is an array of multiple video file names

for(file of files) {
  transcode(file);
  //Transcodes and sends the data to server B.
}

//The ffmpeg command that above function is using to transmit the data is
//ffmpeg -y -hide_banner -loglevel error -re -i file_1.mp4 -vcodec libx264 -acodec aac -c:s copy -map 0 -mpegts_flags pat_pmt_at_frames -f mpegts tcp://147.261.97.32


  


  The problem is when I play the stream as a client, it always freezes when first program ends and next one starts. I log the transferred data and data is coming correctly. which means following loop is working and transferring files one after another. But why does it freeze in player ?

  


• Revision 869d4ca519 : Add adaptation option for VBR. Allow min and maxQ to creep when the undershoot

  9 octobre 2014, par Paul Wilkins

  Changed Paths :
   Modify /vp9/encoder/vp9_firstpass.c

  
   Modify /vp9/encoder/vp9_firstpass.h

  
   Modify /vp9/encoder/vp9_ratectrl.c

  
   Modify /vp9/encoder/vp9_ratectrl.h

  
  
  Add adaptation option for VBR.

  Allow min and maxQ to creep when the undershoot
  or overshoot exceeds thresholds controlled by the
  command line under_shoot_pct and over_shoot_pct
  values.

  Default is 100%,100% which disables adaptation.

  Derf results for example undershoot% / overshoot% :-

  Head :- Mean abs (%rate error) = 14.4%

  This check in :-
  25%/25% - Mean abs (%rate error) = 6.7%
  PSNR hit -1% SSIM -0.1%

  5% / 5% - Mean abs (%rate error) = 2.2%
  PSNR hit -3.3% SSIM - 1.1%

  Most of the remaining error and most of the quality hit is
  at extreme data rates. The adaptation code still has an
  exception for material that is in effect static so that we
  don’t over adjust and over spend on YT slide show type
  content.

  Change-Id : If25a2449a415449c150acff23df713e9598d64c9

• How to replace AAC in 265 MP4s with PCM with ffmpeg

  31 mars 2022, par Jamie Hutber

  I am trying to re encode my h265 files from AAC to PCM audio for the ability to edit them in Davinci Resolve.

  


  I originally used this for h264 files and replaced the codec with hevc_mp4toannexb out.h265 but with no luck !

  


  ## .sh script

#!/bin/bash
for f in *.mp4; \
  do ffmpeg -i "$f" "${f/%mp4/wav}"; \
  ffmpeg -i "$f" -vcodec copy -an -bsf:v hevc_mp4toannexb "${f/%mp4/m4v}"; \
  ffmpeg -i "${f/%mp4/m4v}" -i "${f/%mp4/wav}" \
         -acodec copy -vcodec copy "${f/%mp4/mov}"; \
  rm "${f/%mp4/m4v}"; \
  rm "${f/%mp4/wav}"; \
done