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• Media Source Extensions - Identifying when there is no more data

  8 octobre 2015, par galbarm

  I’m creating a fragmented MP4 of a real-time live content with constant 10FPS but occasionally a frame gets dropped before being feed to the MP4 creation process.
  The MP4 is transmitted to the web through a web socket.

  Due to the occasional frames drop, the playback speed of the file is effectively slightly greater than 1x, because the player plays at 10FPS.
  Since this is a live content, after some duration, the player reaches the present time and has no data to play.

  Now, to the MSE issue :
  What seems to happen in Chrome, when the player doesn’t have enough data to continue playing, is that it pauses for 1-2 secs, then plays it very fast, and vice versa. So at this point the user experience becomes very bad.
  The issue was discussed here :
  https://www.w3.org/Bugs/Public/show_bug.cgi?id=28379

  My idea to workaround this, is to identify the state (having no more data), change playback rate to 0.9 for a few seconds to allow some buffering, and then switch back to 1.0.
  The problem is that I couldn’t find a way to identify the state.
  The readystate of the media element seems to always have the value of "HAVE_ENOUGH_DATA" even when the issue starts.

  Does the MSE API exposes a way identify the state that I have described ?

• Streaming webcam from ffmpeg to Electron app

  28 mars 2017, par potatoes

  I’m working on a prototype application that consists of an Electron app that talks to a local Flask-based Python service (both on the same machine). On the electron app I want to have a "start" button that has starts to record the machine’s desktop (screencast). I do this by using ffmpeg at the Python backend. In a python subprocess I issue the following command :

  ffmpeg -f gdigrab -framerate 30 -i desktop `outputFile`

  Similarly, I’m able to record the webcam with ffmpeg as follows :

  ffmpeg -f dshow -i video="Integrated Webcam" `outputFile`

  However, I want to be able to stream the webcam to the electron app while recording simultaneously. This is to show a "screencasting" experience at the electron end. So basically my question boils down to streaming to an html5 video element while simultaneously recroding it in ffmpeg. I’ve searched for a way to do so and this page suggest that I can do it over a VLC streaming server locally ? I found a few links but I’m not sure whether I should be starting some kind of RTP server locally and streaming the webcam from ffmpeg to that server which will distribute the stream ? I’m confused about what is needed to make this happen, and any pointers are appretiated ! Thanks !

• Extract raw audio frames from OGG music file with Android NDK

  31 octobre 2018, par thenaoh

  In my Android app, I would like to be able to process audio on the fly from an OGG file by extracting audio samples, process them and redirect them to the audio output.

  I know how to make the last 2 steps using Android NDK, but I don’t know how to extract audio samples to get them in an array of floats or shorts.

  I tried to make this code work that, apparently, can extract raw audio samples on the fly.

  The problem is : I don’t manage to add FFMpeg in my project. I tried many tutorials (like this one), but it seems pretty difficult since I work on Windows. So after a while, I found Prebuild FFMpeg for Android, that seems interesting since it’s available for armeabi-v7a, arm64-v8a, x86 and x86_64 architectures, but again, I don’t understand how to add it in my project.

  I also took a look at libogg, libvorbis and vorbisfile, but I have no idea how to add them in my project.

  So, does anyone have a working example on how to extract audio samples from an OGG file on the fly ?

  Thanks for your help.