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• facing problem in downloading the audio data of a trimmed youtube video using youtube-dl and ffmpeg libraries

  15 mai 2022, par rkc

  I'm trying to download the audio content of a trimmed YouTube video using youtube-dl (v2021.12.17) and FFmpeg (v4.2.2) libraries in python, on Windows 10 PC. I am able to download the audio data when the command is executed on the Pycharm terminal, but not able to download the same content when using os.system() command.

  


  For example, I'm able to download the data when I execute

  


  "ffmpeg -ss 30 -t 10 -i $(youtube-dl -f best -g https://www.youtube.com/watch?v=3NGZcpAZcl0) -- output1.wav"


  


  command on the Pycharm terminal.

  


  But, i'm getting an error, when I try to execute the same in the Editor window as shown below,

  


  os.system('ffmpeg -ss 30 -t 10 -i $(youtube-dl -f best -g https://www.youtube.com/watch?v=3NGZcpAZcl0) -- output1.wav')

error: $(youtube-dl: No such file or directory


  


  I also tried enclosing the $() link in quotes and then executed it. But, after doing this, I am getting a different error as shown below

  


  os.system('ffmpeg -ss 30 -t 10 -i "$(youtube-dl -f best -g https://www.youtube.com/watch?v=3NGZcpAZcl0)" -- output1.wav')

error: $(youtube-dl -f best -g https://www.youtube.com/watch?v=3NGZcpAZcl0): Invalid argument


  


  So, can any of you help me in resolving this error ?

  


• ffmpeg split | merge video voice not sync

  2 août 2022, par Zhang

  there are what i done :

  


  

  1. download a full mp4 file.

  


  2. due to it's watermark(0s-10s), i split the full video into 2 parts from 10second. the first part with watermark.

  


  3. use ffmpeg delogo the first part.

  


  4. merge the two video into a full again.

  


  


  


  wget -O download.mp4
ffmpeg -i download.mp4 -vcodec copy -acodec copy -t 00:00:10 tmp1.mp4
ffmpeg -i download.mp4 -vcodec copy -acodec copy -ss 00:00:10 tmp2.mp4
ffmpeg -i tmp1.mp4 -vf "delogo=x=432:y=44:w=1060:h=108" -c:a copy tmp3.mp4
echo file tmp3.mp4 > mergelist.txt && echo file tmp2.mp4 >> mergelist.txt
ffmpeg -f concat -i mergelist.txt -c copy output.mp4


  


  


  problem i faced :
in the last merged video, only one tmp part is fine, the other's video and voice not sync and play time more faster than before.

  


  why i divide it, delogo(although only the first 10 seconds shows) full video more than 1h, re-encode takes much time, 10s part fine to me.

  


• Why are there multiple .m3u8 requests made by the browser ?

  20 mai 2020, par 47fa0c

  I usually download my lectures instead of watching them on the online player provided by my university. I do this by finding requests that include .m3u8 in their url. There always seems to be two of these for each of the videos that I want to download, with one slight difference in the urls but otherwise identical. Why is that the case ?

  



  My wild guess is that one of them is supposed act as a backup if the other failed to fetch but I am not sure.

  



  I can't share the urls as they contain copyrighted material but it looks something like

  



  domain/a/b/hashedvalue1/c/video.mp4/index.m3u8


  



  and

  



  domain/a/b/hashedvalue2/c/video.mp4/index.m3u8


  



  Thanks for your help :)