Force Stream Quality

Quality selection was one of the most requested features and it is implemented and ready. Let's see how to use it.

How Adaptive Bitrate Works?

Ant Media Server measures the viewers internet speed and sends the best quality according to the internet speed of the viewer.

As an example:

• Assume that there are two bitrates on the server

  • First one is 360p and 800kbps.
  • Second one is 480p and 1500kbps.

• if Viewer internet speed

  • is above 1500kbps, then the resolution with 480p is sent.
  • is between 800kbps and 1500kbps or less than 800kbps, then the resolution with 360p is sent.

Client was getting only what server has sent to.

How to Force Specific Quality?

Client side can force the resolutions which are in the adaptive bitrates. Please keep in mind that if you request a quality whose bitrate is higher than the client's bitrate. You may see some packet drops, pixelations, async etc. Anyway, let us tell how to use that.

• While you play the stream, after you receive play_started notification in WebRTCAdaptor. Call getStreamInfo with webRTCAdaptor.getStreamInfo({your_stream_Id});

  else if (info == "play_started") 
  {
    console.log("play started");
    webRTCAdaptor.getStreamInfo(streamId);
  } 
  else if (info == "play_finished") 
  {
  ...

How To Get The {the_resolution_to_be_forced} From The getStreamINFO?

Calling getStreamInfo methods makes server to send streamInformation callback which returns stream information such as adaptive resolutions, audio bitrate, video bitrate etc.

• When server sends the streamInformation, you can get stream details like following:

  else if (info == "streamInformation") {
  
       var streamResolutions = new Array();
  
       obj["streamInfo"].forEach(function(entry) {
          //It's needs to both of VP8 and H264. So it can be duplicate
          if(!streamResolutions.includes(entry["streamHeight"])){
             streamResolutions.push(entry["streamHeight"]);	
  
          }// Got resolutions from server response and added to an array.
  
        });
        
  }// After getting stream information, forceStreamQuality can be used with the information we got.
  else if (info == "ice_connection_state_changed"){
  ...
  

• After getting stream info, you can call the following function to force the video quality you want to watch:

  webRTCAdaptor.forceStreamQuality("{your_stream_Id}",  {the_resolution_to_be_forced});
  

• There is a working sample in player.html as shown below. When you choose resolution, it'll force the quality. As you can see from the screenshot below, you can select the resolution.

Currently 240p is selected and as you can see bitrate is 500000.