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• How to detect noisy R channel in ffmpeg ? [closed]

  17 novembre 2024, par davidvankemenade

  Does anyone know how ffmpeg can identify that the R channel in the example below is noisy ?

  


  waveform : noisy R channel
flac file with noisy R channel

  


  For reference, the following file's R channel is not noisy (except from the first few seconds) :

  


  waveform : normal R channel
flac file with normal R channel

  


  How could ffmpeg be used to classify the first file as "poor" and the second file as "OK" ?

  


  I've not yet been able to find an example to solve this problem.

  


• FFMPEG : Youtube streaming quality and speed issues

  25 février 2020, par Alex Paramonov

  I am trying to make a reliable stream from my Icecast/Shoutcast servers to Youtube live. The command that I use is :

  ffmpeg -v verbose -framerate 30 -loop 1 -i /var/image.jpg -re -i http://127.0.0.1:4700/radio -c:v libx264 -preset ultrafast -b:v 2250k -maxrate 6000k -bufsize 6000k -c:a copy -ab 128k -s 1920x1080 -framerate 30 -g 60 -keyint_min 60 -f flv  rtmp://a.rtmp.youtube.com/live2/xxx

  As you can see I am using recommended bitrate for Youtube, insert keyframes every 2 seconds and streaming at 30 frames per second.
  The stream is working but after running for some time two thing are happening :

  1. FFMPEG speed falls from 1x to something like 0.998x
  2. Youtube starts complaining that video stream speed is slow, markes the quality as bad and sometimes video starts buffering.

  Why is this happening ? CPU load is normal, connectivity is ok (the stream is running on a 1Gg/s dedicated server).

  Since in my example above I am streaming a single image as a logo of the stream I also tried to generate a short 30 seconds video with that image and broadcast that video instead of an image, but that did not help as well.

  The command I used for conversion :

  ffmpeg -framerate 30 -loop 1 -i /var/image.jpg -c:v libx264 -preset ultrafast -tune stillimage  -b:v 2250k -minrate 2250k -maxrate 6000k -bufsize 6000k -framerate 30 -g 60 -keyint_min 60 -t 30 out4.mp4

  And broadcast with

  ffmpeg -stream_loop -1 -i out4.mp4  -re -i http://127.0.0.1:4700/radio -c:v copy -c:a copy  -framerate 30 -g 60 -keyint_min 60 -f flv  rtmp://a.rtmp.youtube.com/live2/xxx

  ffmpeg version is 4.1.1

• How can I construct an mp4 with 6 equal audio channels (not 5p1) from an mp4 and a 6 channel wav

  6 août 2021, par ncvp

  OS is Ubuntu Linux.
I start with xxx.webm with picture and synced mono sound.
I construct the 6 channel xxx.wav which has the sound from xxx.webm moved to the 6 channels as appropriate.

  


  % ffmpeg -i xxx.webm -i xxx.wav -map 0:v -map 1:a yyy.mp4

  


  makes the synced yyy.mp4 with 6 audio channels, but the soundtrack is 5p1. Channel 4 is low-pass filtered. This is not what I want.

  


  % ffmpeg -i xxx.webm -i xxx.wav -map 0:v -map 1:a -channel_layout 6.0 yyy.mp4

  


  is an improvement. Channel 4 is not low-pass filtered and it plays perfectly in ffplay and mplayer, but not VLC player.

  


  It turns out there is no channel-layout in yyy.mp4, so there must be something wrong with my -channel_layout 6.0.

  


  Any suggestions, please ?