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• ffmpeg - how to handle video and audio URL's streams separately ?

  13 mai 2022, par Rubem Pacelli

  I am trying to create a zsh function that uses youtube-dl and ffmpeg to download a portion of a YouTube video. I did achieve this goal with the following function :

  


  # $1 - youtube URL
# $2 - start position in hh:mm:ss.msms format (ms=miliseconds)
# $3 - final position in hh:mm:ss.msms format (ms=miliseconds)
# $4 - output file name (optional)
function youtubedl_snippet()(
  local url_stream=$(youtube-dl -f best --get-url $1)
  local output_name=$(youtube-dl --get-title $1)

  ffmpeg -ss $2 -to $3 -i $url_stream -c:v copy -c:a copy ${4:-"$output_name.mp4"}
)


  


  The command youtube-dl -f best --get-url $1 return a single URL with the best possible quality. In order to understand better how ffmpeg works, I tried to create another function with the same goal but with a different approach :

  


  # $1 - youtube URL
# $2 - start position in hh:mm:ss.msms format (ms=miliseconds)
# $3 - final position in hh:mm:ss.msms format (ms=miliseconds)
# $4 - output file name (optional)
# $5 - output video codec type (optional, for instance: libx264)
# $6 - output audio codec type (optional, for instance: aac)
function youtubedl_snippet2()(
  local url_streams=$(youtube-dl --get-url $1)
  local output_name=$(youtube-dl --get-title $1)

  local url_array=(${(f)url_streams}) # expand urls by lines url_array[1] -> video stream url_array[2] -> audio stream

  ffmpeg -ss $2 -to $3 -i ${url_array[1]} -ss $2 -to $3 -i ${url_array[2]} -map 0:v -map 1:a -c:v ${5:-copy} -c:a ${6:-copy} ${4:-"$output_name.mp4"}
)


  


  What I suppose that is going on here :

  


  

  1. url_streams is a line-separated URL. url_array[1] is the video URL and url_array[2] is the audio URL.

  


  2. I am setting both audio and video to the same intervals.

  


  3. I mapped the first stream to video, and the second to audio

  


  4. If $5 and $6 does not give different codecs, ffmpeg just copy from the original source.

  


  


  Well, it seems that everything is ok. But when I try

  


  start=$SECONDS; youtubedl_snippet2 'https://www.youtube.com/watch?v=g-_hVXzkn0o' 00:00:05.00 00:00:15.00; echo "it takes $(( SECONDS - start )) seconds"


  


  It will take 368 seconds. Moreover, I cannot open it in my android (only audio works)

  


  

  


  On the other hand,

  


  start=$SECONDS; youtubedl_snippet 'https://www.youtube.com/watch?v=g-_hVXzkn0o' 00:00:05.00 00:00:15.00; echo "it takes $(( SECONDS - start )) seconds"


  


  takes only 40 seconds, and the video can be played on Android.

  


  Here is the youtubedl_snippet log file. And here is the youtubedl_snippet2 log file.

  


• Can't generate libx264.dll. MinGW : not c Compiler found

  20 avril 2015, par Sandie C

  It’s my first post in a forum ever (and in english...) Any suggestion is welcomed.

  So let’s started !

  My global goal is to recorder/transcoding and dispay an IP Camera stream from a .bat whitch calling vlc.

  I want an asf container containing h264 and aac.

  ---

  .bat :

  cd C :\Program Files (x86)\VideoLAN\VLC

  vlc rtsp ://root:root@ip_adresse/media.amp —sout "#transcode vcodec=x264, vb=112 , acodec==aac, fps=25:duplicatedst=display,dst=standardaccess=file,mux = asf,dst=flux.asf" -v

  ---

  when I first execute this, VLC told me that H264 encoder was not found, so I decided to compile x264.

  I followed this link

  http://www.ayobamiadewole.com/Blog/How-to-build-x264-or-libx264.dll-in-Windows

  I succeed to make the .exe but and when I got to

  ./configure —disable-cli —enable-shared —extra-ldflags=-Wl,—output-def=libx264.def

  minGW shell indicates : not working c compiler found

  I tried to find some answer, but i didn’t found a good one.

  Does anyone have an idea of what i’m doing wrong ?

• Record window from CMD or PowerShell [closed]

  9 octobre 2023, par Pingui

  How can one record a window e.g. from the Command Promt or PowerShell ?

  


  I tried the following CMD-command which in principle works, but it cuts off the window (even with increased video_size 1920x1080, which seems to have no effect at all) :

  


  "C:\[your_path_to]\ffmpeg.exe" -f gdigrab -i title="New Tab - Google Chrome" -framerate 30 -video_size 1920x1080 -c:v libx264 -preset ultrafast -t 5 output.mp4


  


  The goal would be something like the above, but...

  


  

  1. Ideally, the window should be found not by its window title, but by its process name (e.g. chrome.exe)

  


  2. The video should be automatically fitted to the window size (even if larger than 1920x1080)

  


  3. The video-name.mp4 and video duration (-t) should be handed dynamically as input variables

  


  4. If the video-name.mp4 already exists, it should be overwritten without asking

  


  5. The windw should be recorded even if not on top

  


  


  Any solution in CMD, PowerShell or whatever can be called by Window's ShellExecuteW function and passed video-name.mp4 and video duration as inputs would be fine.