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• How to extract audio with youtube-dl on Windows

  25 septembre 2023, par FlyingNimbus

  I want to extract audio from a video downloaded with youtube-dl on Windows. I got youtube-dl working, but am unable to extract the audio. This problem is caused due to not having the correct audio codes installed.

  



  When I try to extract audio it tells me the following :

  



  WARNING: unable to obtain file audio codes with ffprobe


  



  The youtube-dl manual says :

  



  -x -extract-audio    convert video files to audio-only files (requires ffmpeg or avconv and ffprobe or avprobe)


  



  How do I install ffprobe or ffmpeg ? Do I install this on Windows, or do I install this as a Python extension ?

  



  My OS is Windows 7.

  


• Streaming windows desktop to Youtube with ffmpeg [closed]

  23 mai 2021, par rarahim

  I've been spending days trying to stream my live desktop to Youtube using ffmpeg. There are too many questions and answers on SO about this topic but none really works for me, or perhaps because working with ffmpeg is non-trivial task with it's never ending list of available options.

  


  So far, what sort of works for me is using the following (which is a mixture of what was gathered from various sources) :

  


  


  ffmpeg -threads:v 2 -threads:a 8 -filter_threads 2 -thread_queue_size
5096 -f dshow -i video="screen-capture-recorder" -f dshow -i
audio="Stereo Mix (Realtek High Definition Audio)" -pix_fmt yuv420p
-c:v libx264 -qp:v 19 -profile:v high -rc:v cbr_ld_hq -level:v 4.2 -r:v 60 -g:v 120 -bf:v 3 -refs:v 16 -f flv rtmp ://a.rtmp.youtube.com/live2/KEY

  


  


  My questions are :

  


  


  1. how do i only stream video ? i do not want to stream audio, simply removing '-f dshow -i audio="Stereo Mix (Realtek High Definition Audio)"' causes it to fail

     


  


  2. after a while, ffmpeg starts to hog my memory causing my system to slow down terribly, what causes this and how can i fix it ?

     


  


  3. my video feed when viewed from Youtube keeps buffering rather frequently, how can this be fixed/improved ?

     


  


  


  Thanks.

  


  UPDATE :
I've managed to somewhat figure out a workaround for these issues. Not sure if these are the right solutions but they work for now.

  


  


  1. Youtube apparently requires streams to have audio component. So instead of just removing the audio device form the options, i had to put in "-f lavfi -i anullsrc" to use null audio device.

     


  


  2. The memory hog issue was improved by adding "-framerate 10" and "-r 10" to the input and output options, this reduces target frame rate to 10fps.

     


  


  3. The overall stream performance seem to be indirectly improved by doing the above actions.

     


  


  


  So finally the working simplified version of my ffmpeg command is :

  


  


  ffmpeg -framerate 10 -f dshow -i video="screen-capture-recorder" -f
lavfi -i anullsrc -vcodec libx264 -preset:v ultrafast -pix_fmt yuv420p
-f flv -r 10 rtmp ://a.rtmp.youtube.com/live2/KEY

  


  


  I'm updating here in case it might be useful to someone at some point in the future.

  


• Ghosting in colour channels

  24 mai 2024, par Blikpils

  This seems like a very specific question so i hope there is someone who can help me out.
Within FFMPEG i am trying to add (channel pack) 3 different grayscale videos in RGB within a webm or mp4 video. I got it to work to a degree via Merge planes.
This is what i tried :

  


  ffmpeg -y -i video1.webm -i video2.webm -i video3.webm -filter_complex "[0:v]format=gray[r]; [1:v]format=gray[g]; [2:v]format=gray[b]; [g][b][r]mergeplanes=0x001020:format=gbrp" -pix_fmt yuv420p -t 00:00:03 output.webm


  


  This is the result :


  


  As you see the 9 is visible in the red and blue channel and so are each of the other channels

  


  I have tried just extracting a single channel in a video, change the compression change the format change the color space, make sure that its all linear but each seem to have the limitation of some smearing/artifacts between the other channels.

  


  Is it at all possible to add different grayscale streams in the color channels without any artifacts and if so in which direction should i look ?

  


  Any help would be greatly appreciated !