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• ffmpeg : concat syntax for avi files with different frame rate

  21 février 2020, par suste88

  What is the cli syntax to concat several avi files with different fps into one ?

  ffmpeg -f concat -safe 0 i myListOfAvi.txt -c:v copy output.avi

  I want to keep the fps as it is(dont want to covert all avi fps to same). For example : I have avi files with 5, 10, 15, 20 fps and want output file after concatentation to have fps 5 , then 10, then 15 and so on(simply join the video).
  Right now avi files concatenation using this command line gives me 20 minutes long video instead of a minute long video. Have not figured out what is causing it. The same syntax works for creating output in mp4 format though, but it gets stuck in first frame for five seconds at the start.

• Problems with using on user computers without ffmeg

  8 janvier 2021, par DevilPD

  My Python program uses ffmpeg. However, if ffmeg was installed on your computer at the time of deployment and is not configured or does not exist in a directory such as the exe file, it will not work normally. If my program has to use ffmpeg while running, I would like to use it in the same folder in the library folder. What should I do ?

  


    try:
        for i in sp_text:
            try:
                output_dir = os.path.join('./', '%(playlist_title)s', '%(playlist_index)s. %(title)s.%(ext)s')

                download_list = [
                    i,
                ]

                ydl_opt = {
                    'outtmpl': output_dir,
                    'format': 'bestaudio/best',
                    'postprocessors': [{
                        'key': 'FFmpegExtractAudio',
                        'preferredcodec': 'mp3',
                        'preferredquality': '192',
                    }, {'key': 'FFmpegMetadata'}, ],
                }

                with youtube_dl.YoutubeDL(ydl_opt) as ydl:
                    ydl.download(download_list)

                self.lbl.setText('Success!')
            except:
                self.lbl.setText('Error1')
    except:
        self.lbl.setText('Error2')


  


• FFmpeg - convert 2 audio tracks from video to 5.1 audio, (play video with different languages to different devices) [closed]

  10 février, par Sandre

  How to watch a movie with one language playing through the speakers and another through the headphones ?

  


  Disclaimer : I know nothing about audio conversion, and don't want to study ffmpeg. I spend a few hours searching how to do, actually much more than I want. I found a bunch of questions from different people and not a single working solution, so I made a clunky but working solution. If someone helps me make it more elegant, I'll be happy. If my question just gets downvoted like most ffmpeg newbie questions, it probably deserves it. And I hope my question can help people who want enjoy video with 2 different languages.

  


  A clumsy but working solution.

  


  


  1. Setup Aggregate Audio Device to play 2 channels of 5.1 through speakers and 2 through bluetooth headphones. (On screenshot Audio MIDI Setup for MacOS)


     


  


  2. Use ffmpeg to convert 2 audio tracks into 5.1 audio.

     


  


  3. Play video with new external audio track.

     


  


  


  # print list of channels
ffprobe INPUT.mkv 2>&1 >/dev/null | grep Stream

--- sample output ---
    Stream #0:0(eng): Video: h264 (High), yuv420p(progressive), 1280x544, SAR 1:1 DAR 40:17, 23.98 fps, 23.98 tbr, 1k tbn (default)
    Stream #0:1(rus): Audio: ac3, 48000 Hz, 5.1(side), fltp, 448 kb/s (default)
    Stream #0:2(eng): Audio: ac3, 48000 Hz, 5.1(side), fltp, 640 kb/s

# extract audio
ffmpeg -i INPUT.mkv -map 0:1 -acodec copy ru.ac3
ffmpeg -i INPUT.mkv -map 0:2 -acodec copy en.ac3

# extract only front_center channel from 5.1 - speach
ffmpeg -i en.ac3 -filter_complex "channelsplit=channel_layout=5.1:channels=FC[center]" -map "[center]" en_front_center.wav
ffmpeg -i ru.ac3 -filter_complex "channelsplit=channel_layout=5.1:channels=FC[center]" -map "[center]" ru_front_center.wav

# join to 5.1
ffmpeg -i en_front_center.wav -i ru_front_center.wav -filter_complex "[0:a][0:a][0:a][0:a][1:a][1:a]join=inputs=6:channel_layout=5.1[a]" -map "[a]" output.wav


  


  Is it possible to avoid re-encoding the audio and copying the same channel many times to reduce the file size ?