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• Working with ffmpeg in Xamarin Android

  20 avril 2017, par Ahmed Mujtaba

  I’m building an android app using Xamarin. The requirement of the app is to capture video from the camera and encode the video to send it across to a server. Initially I was using an encoder library on the server side to encode recorded video but it was proving to be extremely unreliable and inefficient specially for large sized video files. I have posted my issues on another thread here I then decided to encode the video on the client side and then send it to the server. I’ve found encoding to be a bit complicated and there isn’t much information available on how this can be done so I search for the only way I knew how to encode a video that is by using ffmpeg codec. I’ve found some solutions. There’s a project on github that demonstrates how ffmpeg is used inside a Xamarin android project. However running the solution doesn’t give any output. The project has a binary ffmpeg file which is installed to the phone directory using the code below :

  _ffmpegBin = InstallBinary(XamarinAndroidFFmpeg.Resource.Raw.ffmpeg, "ffmpeg", false);

  Below is the example code for encoding video into different set of outputs :

              _workingDirectory = Android.OS.Environment.ExternalStorageDirectory.AbsolutePath;
  
          var sourceMp4 = "cat1.mp4";
  
          var destinationPathAndFilename = System.IO.Path.Combine (_workingDirectory, "cat1_out.mp4");
  
          var destinationPathAndFilename2 = System.IO.Path.Combine (_workingDirectory, "cat1_out2.mp4");
  
          var destinationPathAndFilename4 = System.IO.Path.Combine (_workingDirectory, "cat1_out4.wav");
  
          if (File.Exists (destinationPathAndFilename))
  
              File.Delete (destinationPathAndFilename);
  
          CreateSampleFile(Resource.Raw.cat1, _workingDirectory, sourceMp4);
  
  
  
  
  
          var ffmpeg = new FFMpeg (this, _workingDirectory);
  
  
  
          var sourceClip = new Clip (System.IO.Path.Combine(_workingDirectory, sourceMp4));
  
  
  
          var result = ffmpeg.GetInfo (sourceClip);
  
  
  
          var br = System.Environment.NewLine;
  
  
  
          // There are callbacks based on Standard Output and Standard Error when ffmpeg binary is running as a process:
  
  
  
          var onComplete = new MyCommand ((_) => {
  
              RunOnUiThread(() =>_logView.Append("DONE!" + br + br));
  
          });
  
  
  
          var onMessage = new MyCommand ((message) => {
  
              RunOnUiThread(() =>_logView.Append(message + br + br));
  
          });
  
  
  
          var callbacks = new FFMpegCallbacks (onComplete, onMessage);
  
  
  
          // 1. The idea of this first test is to show that video editing is possible via FFmpeg:
  
          // It results in a 150x150 movie that eventually zooms on a cat ear. This is desaturated, and there's a fade in.
  
  
  
          var filters = new List<videofilter> ();
  
          filters.Add (new FadeVideoFilter ("in", 0, 100));
  
          filters.Add(new CropVideoFilter("150","150","0","0"));
  
          filters.Add(new ColorVideoFilter(1.0m, 1.0m, 0.0m, 0.5m, 1.0m, 1.0m, 1.0m, 1.0m));
  
          var outputClip = new Clip (destinationPathAndFilename) { videoFilter = VideoFilter.Build (filters)  };
  
          outputClip.H264_CRF = "18"; // It's the quality coefficient for H264 - Default is 28. I think 18 is pretty good.
  
          ffmpeg.ProcessVideo(sourceClip, outputClip, true, new FFMpegCallbacks(onComplete, onMessage));
  
  
  
          //2. This is a similar version version in command line only:
  
          string[] cmds = new string[] {
  
              "-y",
  
              "-i",
  
              sourceClip.path,
  
              "-strict",
  
              "-2",
  
              "-vf",
  
              "mp=eq2=1:1.68:0.3:1.25:1:0.96:1",
  
              destinationPathAndFilename2,
  
              "-acodec",
  
              "copy",
  
          };
  
          ffmpeg.Execute (cmds, callbacks);
  
  
  
          // 3. This lists codecs:
  
          string[] cmds3 = new string[] {
  
              "-codecs",
  
          };
  
          ffmpeg.Execute (cmds, callbacks);
  
  
  
          // 4. This convers to WAV
  
          // Note that the cat movie just has some silent house noise.
  
          ffmpeg.ConvertToWaveAudio(sourceClip, destinationPathAndFilename4, 44100, 2, callbacks, true);
  
  </videofilter>

  I have tried different commands but no output file is generated. I have tried to use another project found here but this one has the same issue. I don’t get any errors but no output file is generated. I’m really hoping someone can help me find a way I can manage to use ffmpeg in my project or some way to compress video to transport it to the server.

  I will really appreciate if someone can point me to the right direction.

• Optical Drive Value Proposition

  28 août 2010, par Multimedia Mike — General

  I have the absolute worst luck in the optical drive department. Ever since I started building my own computers in 1995 — close to the beginning of the CD-ROM epoch — I have burned through a staggering number of optical drives. Seriously, especially in the time period between about 1995-1998, I was going through a new drive every 4-6 months or so. This was also during that CD-ROM speed race where the the drive packages kept advertising loftier ‘X’ speed ratings. I didn’t play a lot of CD-ROM games during that timeframe, though I did listen to quite a few audio CDs through the computer.

  
  
  

  I use “optical drive” as a general term to describe CD-ROM drives, CD-R/RW drives, DVD-ROM drives, DVD-R/RW drives, and drives capable of doing any combination of reading and writing CDs and DVDs. In my observation, optical media seems to be falling out of favor somewhat, giving way to online digital distribution for things like games and software, as well as flash drives and external hard drives vs. recordable or rewritable media for backup and sneakernet duty. Somewhere along the line, I started to buy computers that didn’t even have optical drives. That’s why I have purchased at least 2 external USB drives (seen in the picture above). I don’t have much confidence that either works correctly. My main desktop until recently, a Mac Mini, has an internal optical drive that grew flaky and unreliable a few months after the unit was purchased.

  I just have really rotten luck with optical drives. The most reliable drive in my house is the one on the headless machine that, until recently, was the main workhorse on the FATE farm. The eject switch didn’t work correctly so I have to log in remotely, 'sudo eject', walk to the other room, pop in the disc, walk back to the other room, and work with the disc.

  Maybe optical media is on its way out, but I still have many hundreds of CD-ROMs. Perhaps I should move forward on this brainstorm to archive all of my optical discs on hard drives (and then think of some data mining experiments, just for the academic appeal), before it’s too late ; optical discs don’t last forever.

  So if I needed a good optical drive, what should I consider ? I’ve always been the type to go cheap, I admit. Many of my optical drives were on the lower end of the cost spectrum, which might have played some role in their rapid replacement. However, I’m not sold on the idea that I’m getting quality just because I’m paying a higher price. That LG unit at the top of the pile up there was relatively pricey and still didn’t fare well in the long (or even medium) term.

  Come to think of it, I used to have a ridiculous stockpile of castoff (but somehow still functional) optical drives. So many, in fact, that in 2004 I had a full size PC tower that I filled with 4 working drives, just because I could. Okay, I admit that there was a period where I had some reliable drives.

  That might be an idea, actually– throw together such a computer for heavy duty archival purposes. I visited Weird Stuff Warehouse today (needed some PC100 RAM for an old machine and they came through) and I think I could put together such a box rather cheaply.

  It’s a dirty job, but… well, you know the rest.

• Anomalie #2024 (Nouveau) : langue des boutons d’admin

  7 avril 2011, par jluc -

  Sur spip.net, depuis plusieurs années, le texte des boutons d’admin m’apparaît en espagnol alors que tous mes paramétrages (espace perso, navigateur etc) sont en français. Je me souviens qu’un habitué d’IRC constatait également ce même (...)