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• Releasing GME Players and Tools

  22 mai 2012, par Multimedia Mike — General, alsa, github, gme, pulseaudio, Python, sdl

  I just can’t stop living in the past. To that end, I’ve been playing around with the Game Music Emu (GME) library again. This is a software library that plays an impressive variety of special music files extracted from old video games.

  I have just posted a series of GME tools and associated utilities up on Github.

  Clone the repo and try them out. The repo includes a small test corpus since one of the most tedious parts about playing these files tends to be tracking them down in the first place.

  Players
  At first, I started with trying to write some simple command line audio output programs based on GME. GME has to be the simplest software library that it has ever been my pleasure to code against. All it took was a quick read through the gme.h header file and it was immediately obvious how to write a simple program.

  First, I wrote a command line tool that output audio through PulseAudio on Linux. Then I made a second program that used ALSA. Guess what I learned through this exercise ? PulseAudio is actually far easier to program than ALSA.

  I also created an SDL player, seen in my last post regarding how to write an oscilloscope. I think I have the A/V sync correct now. It’s a little more fun to use than the command line tools. It also works on non-Linux platforms (tested at least on Mac OS X).

  Utilities
  I also wrote some utilities. I’m interested in exporting metadata from these rather opaque game music files in order to make them a bit more accessible. To that end, I wrote gme2json, a program that uses the GME library to fetch data from a game music file and then print it out in JSON format. This makes it trivial to extract the data from a large corpus of game music files and work with it in many higher level languages.

  Finally, I wrote a few utilities that repack certain ad-hoc community-supported game music archives into... well, an ad-hoc game music archive of my own device. Perhaps it’s a bit NIH syndrome, but I don’t think certain of these ad-hoc community formats were very well thought-out, or perhaps made sense a decade or more ago. I guess I’m trying to bring a bit of innovation to this archival process.

  Endgame
  I haven’t given up on that SaltyGME idea (playing these game music files directly in a Google Chrome web browser via Google Chrome). All of this ancillary work is leading up to that goal.

  Silly ? Perhaps. But I still think it would be really neat to be able to easily browse and play these songs, and make them accessible to a broader audience.

• Unable to find audio stream

  18 novembre 2011, par Kurt

  I'm trying to adapt a code in order to add a sound capture feature (on a live stream), with the help of ffmpeg and directshow.

  When i try to play with ffplay the AVIsynth file, everything works perfectly i've got the audio and video. But when i open this input file by code i only find the video stream.

  The Avs file :

  V = DirectShowSource("Decklink_HDMI.grf", fps=10, framecount=1000000000, seek=false, audio=false)
  
  A = DirectShowSource("Decklink_Audio.grf", fps=1, framecount=1000000000, video=false)
  
  AudioDub(V, A)

  The opening code :

  ffmpeg::AVInputFormat * ifmt;
  
  
  
  ifmt = ffmpeg::av_find_input_format("avs");
  
  
  
  // Open input file
  
   if(ffmpeg::avformat_open_input(&pFormatCtx, filename.toStdString().c_str(), ifmt, NULL) != 0)

  When i make a variable lookout on gdb just after the opening.

  i'm looking at nb_streams in pFormatCtx->nb_streams and it's at 1
  The only stream i can find in pFormatCtx->stream is a video one. And that's why i'm not able to capture the sound.

  So i'm asking if i'm doing something wrong with my opening or if i miss something.

  Ps : I know the code shown is short but the problem appears at this very step !

  Thank you

  Kurt

  — EDIT —

  I've also noticed that when I dump the AVFormatContext the video stream got a 456x32 size.
  And i can find this very same size of the window displayed when i try to launch a corrupted script with ffplay.

  The original video format when i play the correct script with ffplay is of 1920x1080

  I think my problem is maybe deeper than the simple fact of not being able to get the audio stream.

  I'm trying to find out how to know the error message that is displayed on this 456x32 windows

  — EDIT2 —

  I Find out what is written on this image and my problem is solved, badly placed avs script an old one was is place.

  I'm ashamed.

• Using C# and ffmpeg to rip audio from an .mp4, ffmpeg stuck until closing the calling application

  19 juillet 2018, par user3806186

  I happened to find this answer :
  https://stackoverflow.com/questions/44981454/c-sharp-extract-mp3-file-from-mp4-file#=

  And it seems to work, However, the conversion process gets stuck, and it only resumes after I have closed the application that called ffmpeg to run.

  The following code is responsible for the launch of ffmpeg :
  (The commented lines are just from testing on how to fix the hanging)

          public static string ConvertToMp3(string inputFile, string outputFile = "extracted_audio.mp3")
  
      {
  
          Console.WriteLine("Converting mp3 to " + Path.GetFullPath("extracted_audio.mp3"));
  
          string mp3out = "";
  
  
  
          try
  
          {
  
              if (ffmpegProcess != null)
  
                  ffmpegProcess.Kill();
  
  
  
              ffmpegProcess = new Process();
  
              ffmpegProcess.StartInfo.UseShellExecute = false;
  
              ffmpegProcess.StartInfo.RedirectStandardInput = true;
  
              ffmpegProcess.StartInfo.RedirectStandardOutput = true;
  
              ffmpegProcess.StartInfo.RedirectStandardError = true;
  
              ffmpegProcess.StartInfo.CreateNoWindow = true;
  
              ffmpegProcess.StartInfo.FileName = Path.GetDirectoryName(System.Diagnostics.Process.GetCurrentProcess().MainModule.FileName) + @"\bin\ffmpeg.exe";
  
              ffmpegProcess.StartInfo.Arguments = "-i " + Path.GetFullPath(inputFile) + " -vn -f mp3 -ab 320k output " + Path.GetFullPath(outputFile);
  
              ffmpegProcess.Start();
  
              ffmpegProcess.StandardOutput.ReadToEnd();
  
              mp3out = ffmpegProcess.StandardError.ReadToEnd();
  
              //ffmpegProcess.WaitForExit();
  
              if (!ffmpegProcess.HasExited)
  
              {
  
                  //ffmpegProcess.Kill();
  
              }
  
          }
  
          catch (InvalidOperationException e)
  
          {
  
              Console.WriteLine("mp3 conversion failed: " + e.Message);
  
              return "";
  
          }
  
  
  
          return mp3out;
  
      }

  I have no idea what causes the halting, any ideas ?