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• Does android support .m4a metadata ?

  23 octobre 2016, par David Barishev

  Im using taglib-sharp-portable to tag audio files in my app. My audio files are .acc, which are inboxed in a .m4a format.
  I have no option but to use this format, since i’m extracting the audio from a Video file (.mp4/.webm), based on using this SO answer. I can’t re encode the music stream, since it will take a lot of time on an cellular device.
  The problem i’m facing is that the music player doesn’t recognize the tags, even though they are tagged correctly. If i pull the file from the device, and view it on my Windows PC, i can see the tags fine.

  Here is the code im using to tag the file :

  public static async Task tagFile(File musicFile, string name, string songID, Context c, SongDownloadNotification nf = null)
  
  { 
  
              var imageFilePath = await DownloadThumbnailImage(songID, c, nf);
  
              string[] songDetails = GetSongDetails(name);
  
  
  
              Log.Verbose(tag, "Exstraced song Details. Artist Name: {0}, Song Name: {1}", songDetails[0], songDetails[1]);
  
  
  
              var fsMusic = new System.IO.FileStream(
  
                  musicFile.CanonicalPath,
  
                  System.IO.FileMode.Open,
  
                  System.IO.FileAccess.ReadWrite,
  
                  System.IO.FileShare.ReadWrite,
  
                  4096,
  
                  true);
  
  
  
              TagLib.File tagFile = TagLib.File.Create(new TagLib.StreamFileAbstraction(musicFile.CanonicalPath, fsMusic, fsMusic));
  
  
  
              tagFile.Tag.Clear();
  
  
  
              tagFile.Tag.Performers = new[] { songDetails[0] };
  
              tagFile.Tag.AlbumArtists = new[] { songDetails[0] };
  
              tagFile.Tag.Title = songDetails[1];
  
              tagFile.Tag.Album = songDetails[1];
  
  
  
              var fsImage = new System.IO.FileStream(
  
                  imageFilePath,
  
                  System.IO.FileMode.Open,
  
                  System.IO.FileAccess.ReadWrite,
  
                  System.IO.FileShare.ReadWrite,
  
                  4096,
  
                  true);
  
  
  
              tagFile.Tag.Pictures = new[] { new TagLib.Picture(new TagLib.StreamFileAbstraction(musicFile.CanonicalPath, fsImage, fsImage)) };
  
  
  
              tagFile.Save();
  
              Log.Debug(tag, "Succesfully added tags to file");
  
  
  
              fsMusic.Close();
  
              fsImage.Close();
  
  
  
              if (!new File(imageFilePath).Delete())
  
                  Log.Warn(tag, "Couldnt delete tmp file");
  
              else
  
                  Log.Verbose(tag, "Deleted thumbnail file succesfully");
  
  } 

  These question came to me :

  • Is my choice of encapsulating the raw .acc file in .m4a file good ? The format im looking into, is audio only, is .m4a overkill for it ?
  • Does android support reading tags of .m4a file ? If so what did i do wrong with my code ?If not, how can i add tags to .acc ( or some other ’parent’ format), that android supports, and i would not need to re encode it ?

• ffmpeg record audio from Xvfb on Centos

  25 mai 2017, par boygiandi

  I’m trying to record audio from Xvfb. And I have some problems :

  1. What’s the different between alsa and pulse. I get confuse
  2. Server Centos have no soud card :

  arecord -l

  arecord : device_list:268 : no soundcards found...

  3. I may have many Xvfb process, how to record video and audio from specific Xvfb process. I checked this https://trac.ffmpeg.org/wiki/Capture/ALSA#Recordaudiofromanapplication but still don’t understand how it works.

  ffmpeg -f alsa -ac 2 -i hw:0,0 -acodec pcm_s16le output.wav

  I seen many command like this, but I don’t know how to get hw:0,0 ( id of sound card ? )

  Please help. Thanks

• #/bin/sh in one line

  27 juillet 2012, par GoodGuyGreg

  I'm working on some Haskell project using FFmpeg. I need to batch create from a media folder with MP4 files and create screenshots from all of them. I got the code and am using it on a terminal in Unix. It works, but how do I make it in one line to be executed in system "xxxx" in Haskell ?

  If not using several system"xx"...

  #/bin/sh
  
  for i in $(ls *.mp4)
  
  do
  
      ffmpeg -i $i -vframes 7 -y -ss 10 -s 150x150 -an -sameq -f image2 -r 1/5  $i%1d.jpg
  
  done

  I tried :

  import System.Cmd
  
  function = do{system "#/bin/sh";
  
  system "for i in $(ls *.mp4)";
  
  system "do";
  
  system "ffmpeg -i $i -vframes 7 -y -ss 10 -s 150x150 -an -sameq -f image2 -r 1/5  $i%1d.jpg";
  
  system "done";}

  but it gives a error :

  -vframes: No such file or directory
  
  /bin/sh: Syntax error: "done" unexpected