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• vc2enc_dwt : use 32 bit coefficients by default

  7 mai 2016, par Rostislav Pehlivanov

  vc2enc_dwt : use 32 bit coefficients by default
  The problem is that with particularly complex images and especially at
  
  high bit depths and 5-level transforms the coefficients would overflow,
  
  causing huge artifacts to appear. This was discovered thanks to the fate
  
  tests, which will have to be redone as this fixes a multitude of
  
  problems and increases PSNR.
  There is a slight performance drop associated with this change, making
  
  the encoder slower by 1.15 times, however this is necessary in order to
  
  avoid undefined behavior and overflows.
  It would be worth to template the transforms to keep the performance for
  
  8 bit images as 32 bit coefficients are unnecessary for that case, but
  
  the primary use of the encoder is to encode video at 10 bits.
  Reviewed-by : Christophe Gisquet <christophe.gisquet@gmail.com>
  
  Reviewed-by : Michael Niedermayer <michael@niedermayer.cc>
  
  Signed-off-by : Rostislav Pehlivanov <atomnuker@gmail.com>
  

  • [DH] libavcodec/vc2enc_dwt.h

• bash variable changes in loop with ffmpeg

  17 septembre 2018, par Mike

  I wrote a skript to quickly create short preview clips from vides I recorded on timestamps that I found worth checking out later for cutting.
  My file with the timestamps is written like this

  FILE_NAME1#MM:SS MM:SS
  
  FILE_NAME2#MM:SS MM:SS MM:SS MM:SS

  example :

  MAH01728#02:47 03:34 03:44 05:00 06:08 06:55

  The script looks like this :

  #!/bin/bash
  
  while read f
  
   do
  
  
  
   file=$(echo $f | cut -d"#" -f1)
  
   filename=${file}".MP4"
  
   timestamps=$(echo $f | cut -d"#" -f2)
  
  
  
  for time in $timestamps 
  
   do 
  
    ffmpeg -ss 00:${time}.0 -i "orig/${filename}" -c copy -t 10 "preview/${file}_${time}.MP4"
  
   done
  
  done < $1

  The script gets half of the previews that I want and on the other the filename is messed up and ffmpeg complains that the file is not found :

  orig/714.MP4: No such file or directory
  
  orig/00:58 01:25.MP4: No such file or directory

  So I modified the script for trouble shooting and just put an echo in front of the ffmpeg command - now all file names are correct. What am I missing ?

  ffmpeg -ss 00:01:47.0 -i orig/MAH01714.MP4 -c copy -t 10 preview/MAH01714_01:47.MP4
  
  ffmpeg -ss 00:02:00.0 -i orig/MAH01713.MP4 -c copy -t 10 preview/MAH01713_02:00.MP4
  
  ffmpeg -ss 00:00:58.0 -i orig/MAH01712.MP4 -c copy -t 10 preview/MAH01712_00:58.MP4
  
  ffmpeg -ss 00:01:25.0 -i orig/MAH01712.MP4 -c copy -t 10 preview/MAH01712_01:25.MP4

• FFMPEG RTMP stream Non-monotonous DTS in output stream 0:1 [closed]

  30 avril 2023, par Tweeno

  Running into a wee issue here.
I'm trying to use an rtmp stream as an input and then outputting it to twitch.
ffmpeg -re -i rtmp://localhost:1935/live/ -f flv -c:v libx264 -c:a aac rtmp://mad01.contribute.live-video.net/app//stream_key

  


  The only issue with this, is that the rtmp sometimes restarts (whenever the video being sent to it ends), and after it restards, it causes this script to output
Non-monotonous DTS in output stream 0:1; previous: 10006, current: timestamp; changing to 10006

  


  This plays the first video fine, but anything after that just stops working.

  


  I believe this would be a fine fix, if it wasn't for the fact that previous and current were ALWAYS the same value (the length of the video sent to the rtmp stream in ms). This should be the reason as of why it just stops outputting, because the current timestamp isn't incrementing at all.
The example I gave was for a 10 second video sent to the rtmp stream.
This issue disappears if the first video was like 10 seconds, and the second one is 20, and it reaches the 10s mark on the second video.

  


  I've tried searching quite literally everywhere but couldn't even find someone with the same issue I have. Appreciate any kind of help