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• FFmpeg trim filter fails to use sexagisimal time specification and the output stream is empty. Is it a bug and is there a fix ?

  29 novembre 2020, par Link-akro

  With ffmpeg the trim filter (or its audio variant atrim) malfunctions whenever i try to write a sexagesimal time specification for the boundaries or duration parameters of the filter : the result is always an empty stream.

  


  According to the documentation i already linked, which was generated on November 26, 2020 so far, the time duration specification should be supported.

  


  


  start, end, and duration are expressed as time duration specifications

  


  


  Quote of the spec.

  


  


  [-][HH :]MM:SS[.m...]

  


  


  


  [-]S+[.m...][s|ms|us]

  


  


  I am working in a Windows_10-64bit and scripting in its CMD.exe command-line, should it matter.

  


  Here is an instance of trimming a video stream out of a media file with hardcoded value for simplicity. The audio is retained unless i use atrim as well.
We may or may not append the setpts filter as recommended in the documentation henceforth setpts=PTS-STARTPTS if we want to shift the stream to start at the beginning of the cut range.

  


      ffmpeg -i sample-counter.mp4 -vf "trim=start=start='1:2':end='1:5'" sample-counter-trimmed.mp4


  


  If i use decimal it works as intended.

  


      ffmpeg -i sample-counter.mp4 -vf "trim=start=start='2':end='5'" sample-counter-trimmed.mp4


  


  This is the banner of my ffmpeg build. We may see it is the latest build by gyan.dev at the moment i post this.

  


      ffmpeg version 4.3.1-2020-11-19-full_build-www.gyan.dev Copyright (c) 2000-2020 the FFmpeg developers
      built with gcc 10.2.0 (Rev5, Built by MSYS2 project)
      configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-lzma --enable-libsnappy --enable-zlib --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libdav1d --enable-libzvbi --enable-librav1e --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libaom --enable-libopenjpeg --enable-libvpx --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint


  


  The incorrect stream is always reported as 0kB weight in the output of ffmpeg. I confirmed with ffprobe Movie_Countdown-trim-2-5.mov -show_streams -show_entries format=duration that the incorrect stream is duration zero.

  


  Should i report it as a bug ? Is there some correction or workaround ?

  


  I would rather a solution with the trim filter itself, but if not possible a CMD batch scripting.
We should not need a different filter like select or seeking option like there are tutorials and questions/answers everywhere already. Scripting would be straight-forward in a proper *nix shell+distrib and taught everywhere so it is not worth caring while CMD answers on the other hand are rare so a scripting workaround for CMD would have some microcosmic worth since making one is considerably less straight-forward than a shell with modern mathematics and parsing abilities built-in or packaged.

  


• Discord.Net sending audio with ffmpeg only works once (the first time)

  16 janvier 2023, par Esko

  Context :

  


  So I am writing a small bot that should play local audio files on command. I am using Discord.Net, ffmpeg, opus and libsodium.
I have a Speak() function that should, in Theory,

  


  Open ffmpeg -> encode .mp3 -> create PCM stream -> pump the encoded .mp3 to the output(PCM Stream).

  


  That looks like this :

  


  public async Task Speak(IGuild guild, Sound.SoundName soundName)
{
  IAudioClient client;
  if (ConnectedChannels.TryGetValue(guild.Id, out client))
  {
    using (var ffmpeg = CreateStream(sound.Filename))
    using (var stream = client.CreatePCMStream(AudioApplication.Voice, 98304))
    using (var output = ffmpeg.StandardOutput.BaseStream)
    {
     try
     {
       await output.CopyToAsync(stream);                            
     }
     catch (Exception ex) { Console.WriteLine("Error " + ex.Message); Console.WriteLine($"- {ex.StackTrace}"); }
     finally { await stream.FlushAsync(); }
     Console.WriteLine("Spoken!");
   }
}

private Process CreateStream(string _path) 
{
  var process = Process.Start(new ProcessStartInfo
                 {
                   FileName = "ffmpeg",
                   Arguments = $"-hide_banner -loglevel panic -i \"{_path}\" -ac 2 -f s16le -ar 48000 pipe:1",
                   UseShellExecute = false,
                   RedirectStandardOutput = true,
                 });
  return process;
}


  


  And it does this, but only one time. A bit more specific, When my bot joins a Voice Channel, it saves the VoiceChannel ID and the IAudioClient in a private static readonly ConcurrentDictionary ConnectedChannels = new ConcurrentDictionary();. After that it automatically calls the Speak() function to play a hello.mp3 audio. This Process is done like this :

  


  [Command("join", RunMode = RunMode.Async)]
[RequireUserPermission(GuildPermission.MentionEveryone)]
public async Task JoinChannel(IVoiceChannel channel = null) 
{
 // Get the Voice channel
 channel = channel ?? (Context.User as IGuildUser)?.VoiceChannel;
 if (channel == null) { await Context.Channel.SendMessageAsync("You are not in a VoiceChannel"); return; }

 // Saving the AudioClient
 var audioClient = await channel.ConnectAsync();
 Console.WriteLine($"Connected to channel {channel.Name}");

 ConnectedChannels.TryAdd(channel.Guild.Id, audioClient);

 await Task.Delay(1000);
 await Speak(Context.Guild, Sound.SoundName.hello);
}


  


  This works pefectly fine, The audio plays.

  


  Now that the bot is connected to a VoiceChannel and the IAudioClient is saved to the Dictionary. I should be able to call the Speak() function whenever i want and from Whereever i want, as long as the bot is in the VoiceChannel, right ?

  


  No it doesnt.

  


  and that takes me to my
  

  


  Problem :

  


  After the bot is now sitting silently in the voice channel i call a "speak" command that looks in code like this :

  


  [Command("speak")]
public async Task speakSingle() 
{
  await Speak(Context.Guild, Sound.SoundName.Random);
}


  


  But the bot remains silent, even though the speak indicator in Discord lights up ! What am I missing ? I dont get it. Is it sending an empty stream ?
  Even when I disconnect the bot from the VoiceChannel an reconnect it It wont send audio. The only thing that helps is Reconectiong the Bot From the Server.
  I am pretty new to C# and Streams and async programing. So could somebody help me out finding the problem and fix it ?

  


  Errors (CommandPromt Ouput) :

  


  1#
  This occures when i run the "speak" command, im getting a NullReferenceException for "Discord.WebSocket.pdb not loaded" in VisualStudio. Allthough I couldn't find anything thats null...

  


  17:34:17 Audio #1    System.Exception: WebSocket connection was closed&#xA; ---> Discord.Net.WebSocketClosedException: The server sent close 4008: "Rate limited."&#xA;   at Discord.Net.WebSockets.DefaultWebSocketClient.RunAsync(CancellationToken cancelToken)&#xA;   --- End of inner exception stack trace ---&#xA;   at Discord.ConnectionManager.&lt;>c__DisplayClass29_0.&lt;<startasync>b__0>d.MoveNext()&#xA;</startasync>

  


  2#
  This occures when the bot rejoined the Voice Channel and automatically executes the Speak() function.

  


  Error A task was canceled.
-    at Discord.Audio.Streams.BufferedWriteStream.WriteAsync(Byte[] data, Int32 offset, Int32 count, CancellationToken cancelToken)
   at Discord.Audio.Streams.OpusEncodeStream.WriteAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancelToken)
   at System.IO.Stream.CopyToAsyncInternal(Stream destination, Int32 bufferSize, CancellationToken cancellationToken)
   at Bot.Modules.VoiceChannel.Speak(IGuild guild, SoundName soundName) in Y:\Dokumente\Coding\C#\Vs_Studio\Bot\Bot\Modules\VoiceChannel.cs:line 90


  


  This is my first Question on StackOverflow and i hope i provieded enough context, if not tell me please.

  


• avformat/hls : Fixes overwriting existing #EXT-X-PROGRAM-DATE-TIME value in HLS playlist

  1er décembre 2020, par Vignesh Ravichandran

  avformat/hls : Fixes overwriting existing #EXT-X-PROGRAM-DATE-TIME value in HLS playlist
  fix ticket : 8989
  This is is due to the following behavior in the current code :
  
  1. The initial_prog_date_time gets set to the current local time
  
  2. The existing playlist (.m3u8) file gets parsed and the segments
  
     present are added to the variant stream
  
  3. The new segment is created and added
  
  4. The existing segments and the new segment are written to the
  
     playlist file. The initial_prog_date_time from point 1 is used
  
     for calculating "#EXT-X-PROGRAM-DATE-TIME" for the segments,
  
     which results in incorrect "#EXT-X-PROGRAM-DATE-TIME" values
  
     for existing segments
  
  The following approach fixes this bug :
  
  1. Add a new variable "discont_program_date_time" of type double
  
     to HLSSegment struct
  
  2. Store the "EXT-X-PROGRAM-DATE-TIME" value from the existing
  
     segments in this variable
  
  3. When writing to playlist file if "discont_program_date_time"
  
     is set, then use that value for "EXT-X-PROGRAM-DATE-TIME" else
  
     use the value present in vs->initial_prog_date_time
  Signed-off-by : Vignesh Ravichandran <vignesh.ravichandran02@gmail.com>
  
  Signed-off-by : liuqi05 <liuqi05@kuaishou.com>
  

  • [DH] libavformat/hlsenc.c