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• Detecting Successful Conversion with ffmpeg

  22 février 2017, par J M

  I have code that scans a file system for videos files encoded with H.264 and re-encodes them with H.265. It runs pretty much on its own constantly, generating various log files for me to review periodically.

  One thing that I want to further improve is the successful conversion detection. Right now, a file returns as being successfully converted after it meets these criteria/checks :

  1. The output file exists
  2. ffprobe can detect that the output file is in hevc format
  3. The duration of the output file matches that of the input file (within 3 seconds)
  4. The length of the output file is greater than 30 MB (it’s rare that I have a video so short where after conversion it is less than this, usually this happens when an error occurs or conversion terminates early).

  Obviously, this is rather computationally intense as there are many file checks to confirm all of this information. I do this because if the file is detected as successful conversion, the old file is overwritten and the new converted file takes it’s place. I don’t want to overwrite a file because I overlooked a scenario where I think conversion is successful but was in fact not. The files are under a crashplan constant backup, so I don’t lose them, but I also do not go through and review every file.

  So, my basic question is if you see any area of improvement for this detection. My goal is to determine, to my best extent, if after conversion the video remains "playable". So deciding programmatically how/what that means is what I’m attempting to do.

  I can post code if you want it (powershell), but the question seems independent of actual program language choice.

• 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 ?

• AForge FFMPEG Video operation issue

  9 janvier 2017, par Berkay

  I have a problem actually an issue about making video of images(captured frames). I am using nVLC to capture my IP camera’s video content. I managed to take these and show them in my application whenever a new frame comes up. But I also need to convert them whenever a user wants to save the record. This record should be long enough like 1-2 hours.

  So I decided to use AForge lib. In this library there is a class called VideoFileWriter.It does what I want. But here is the problem. I am getting 24-25 frames per second and I am drawing it on the screen. This causes a little bit of an overhead to my system (Especially when I am streaming 6 IP cameras to my screen). My CPU is utilized like %50-60 and i am using 500-550 MB of RAM while streaming 6 IP cameras and drawing to my screen.

  So I came up with two ideas,

  • I can process (write to a video file) each frame whenever I capture. (If user starts recording)
  • Or, I can store Bitmaps (captured frames) whenever user starts recording. Then I can process these list of (might be an array or List<> or another container etc...) later.

  The first approach will destroy my pc, because read/write is very very expensive operations for computers, so this will put me in a very bad position.

  Second approach will destroy my ram, because I may end up with 3600*25 frames for each bitmap list. But seems to be the better choice to me.

  Does anyone have any advice on this topic ?