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• Seeking in Libav / FFMPEG a DASH stream

  23 janvier 2018, par Glen Rhodes

  Recently, the functionality for playing DASH format files (mpd) was added to Libav. I’m trying to determine the best way to seek forward in the stream.

  When I use av_seek_frame, it does go to the correct time, but there’s a considerable delay which makes me think it’s not properly jumping to a segment / byte offset in the HTTP request, but rather just downloading with all its might until it arrives at the correct timestamp.

  int ret = av_seek_frame(is->pFormatCtx, stream_index, seek_target, is->seek_flags);

  When I use avformat_seek_file, it only seems to go forward several seconds before just continuing to play. So if I start playback, and then seek to 50 seconds, it will jump to something like 12. If I do the same seek again, it’ll jump further ahead, but still not 50.. however if it eventually gets to 50, then I do avformat_seek_file, it will successfully jump back to 50 no problem. So it’s like it tries, and gives up.

  int ret = avformat_seek_file(is->pFormatCtx, stream_index, INT64_MIN, tm, INT64_MAX, 0);

  Does anyone know how seeking is managed in the Libav dash playback ?

• How to install ffmpeg to Heroku ?

  11 mars 2020, par Gamer Fardin

  I am trying to build a discord bot using discord.py rewrite version, now the problem is I recently updated it to run audio from link and it works fine when I manually run the codes but once I have uploaded it to heroku it doesnt work because(I assume) ffmpeg is not in the right folder and I get the error : ffprobe/avprobe and ffmpeg/avconv not found. please install one. So does anyone how to properly install it to heroku ? Because the usual pip command isnt working...

  ’’’

      @client.command(aliases=["PlayMusic","playmusic","Playmusic","playMusic","PLAYMUSIC","playaudio"])
  
      async def play(ctx, url):
  
          song_there = os.path.isfile("song.mp3")
  
          try:
  
              if song_there:
  
                  os.remove("song.mp3")
  
          except PermissionError:
  
              await ctx.send("Wait for the current playing music end or use the 'stop' command")
  
              return
  
  
  
          voice = get(client.voice_clients, guild=ctx.guild)
  
          print(voice)
  
          ydl_opts = {
  
              'format': 'bestaudio/best',
  
              'postprocessors': [{
  
                  'key': 'FFmpegExtractAudio',
  
                  'preferredcodec': 'mp3',
  
                  'preferredquality': '192',
  
              }],
  
          }
  
          with youtube_dl.YoutubeDL(ydl_opts) as ydl:
  
              ydl.download([url])
  
          for file in os.listdir("./"):
  
              if file.endswith(".mp3"):
  
                  os.rename(file, 'song.mp3')
  
          voice.play(discord.FFmpegPCMAudio("song.mp3"))
  
          voice.volume = 100
  
          voice.is_playing()

  ’’’

• "MPEG audio header not found" error when opening with TagLib after converting with ffmpeg

  6 juillet 2015, par Avrohom Yisroel

  I converted a wma file simply by doing something like this...

  ffmpeg -i song.wma -f mp3 song.mp3

  I can then play the mp3 file in Windows Media player, so it looks like the conversion worked.

  However, if I try to open the file in TagLib, I get an error "MPEG audio header not found" on the following line...

  TagLib.File tf = TagLib.File.Create("song.mp3");

  I’ve tried this on a few wma files, so it’s not just that one that’s at fault.

  Anyone have any idea what I did wrong ? I find the docs for ffmpeg pretty overwhelming, and as a complete ignoramus in the field of audio encoding, I haven’t a clue what most of it means. Could be I’m missing something in the conversion, although that wouldn’t explain why WMP can play it but TagLib can’t open it.