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• How to make ffmpeg respect the "start_time" variable when combining cdg and mp3 ?

  5 juillet 2020, par Steffen Poulsen

  I'm trying to combine two .cdg and .mp3 files because I want to make a single .mkv file out of them.

  



  When I do it I get a .mkv file alright, but the audio is unfortunately not synced with the video.

  



  So, I was wondering why this is ? Apparently I must be missing a parameter on my command or something.

  



  What I do is this :

  



  ffmpeg -y -i song.cdg -i song.mp3 -pix_fmt yuv420p -vcodec libx264 -acodec copy song.mkv


  



  It works fine, but in this particular case the result is out of sync by 1.2 seconds. This varies per song, from 0 to a couple of seconds.

  



  However, if I do a ffprobe on the .cdg file I notice that this number is already present, as the "start_time" variable :

  



  ffprobe -v error -show_format -show_streams song.cdg
...
start_time=1.186667
...


  



  So, if I just use this number directly as this for the -itsoffset parameter :

  



  ffmpeg -y -itsoffset 1.186667 -i song.cdg -i song.mp3 -pix_fmt yuv420p -vcodec libx264 -acodec copy song.mkv


  



  Then the video and audio is in perfect sync.

  



  So, I am wondering - what parameter do I need to add to my command to have ffmpeg respect this variable ?

  


• Create thumbnails of sections of a torrent stream

  14 juillet 2015, par Ortixx

  I’m trying to create a little application in nodejs using the torrent-stream library to create thumbnails of a video without actually having to download the entire file. I was thinking of downloading only 10 parts, out of which I would extract an image, but then the encoding comes into play : without an I-frame I cannot extract an image out of the stream, and there is no way of me knowing where the I-frame is.

  So any ideas on how to do this ? Basically I was hoping to create 10 tiny files which I could then open in ffmpeg in order to save a thumbnail (this would give me 10 thumbnails which is want I want). I’m just not sure how to handle the stream.

• Why does this ffmpeg,exe window keep opening when I run my command ?

  5 avril 2020, par John

  I'm making a discord bot and for this aspect of the bot, I wanted it to play music in the voice channel. Here is my code for it :

  



  @client.command(pass_context=True)
async def play(ctx, url: str):

    song_there = os.path.isfile("song.mp3")
    try:
        if song_there:
            os.remove("song.mp3")
            print("Removed old song file")
    except PermissionError:

        await ctx.send("`There's already a song playing, request your song after!`")
        return

    await ctx.send("`Getting your song ready...`")

    voice = get(client.voice_clients, guild=ctx.guild)

    ydl_opts = {
        'format': 'bestaudio/best',
        'postprocessors': [{
            'key': 'FFmpegExtractAudio',
            'preferredcodec': 'mp3',
            'preferredquality': '192',
        }],
    }

    with youtube_dl.YoutubeDL(ydl_opts) as ydl:
        try:
            print("Downloading audio now\n")
            ydl.download([url])
        except:
            await ctx.send("`Error, that was not a valid url.`")
            return

    for file in os.listdir("./"):
        if file.endswith(".mp3"):
            name = file
            os.rename(file, "song.mp3")

    voice.play(discord.FFmpegPCMAudio("song.mp3"), after=lambda e: print("Song done!"))
    await ctx.send("`Everything went well. Enjoy!`")
    voice.source = discord.PCMVolumeTransformer(voice.source)
    voice.source.volume = 0.07

    nname = name.rsplit("-", 2)
    await ctx.send(f"`Playing: {nname[0]}`")
    print("playing\n")


  



  I got most of it from online sources to be honest. However, whenever someone plays a song, this pops up throughout the song download process. It can be seen here : https://imgur.com/a/iRr0qwj

  



  I don't mind them coming up, but when they do, they override all of my other tabs and pop up so they're the main screen. I'd like for them to pop up in the background, if I can't remove them fully. Can anyone help ? This would be pretty unpractical for me for when multiple use the function, and I can't use my computer anymore (as of now the bot is ran on my computer) without constantly minimizing that screen.

  



  I'm using windows 10, Python 3.7