Adaptive bit rates (ABR) for video quality

HLS and DASH streams provide different bit rate encodings (profiles) for the same short burst of video. TVSDK can select the quality level for each burst based on the available bandwidth.

TVSDK constantly monitors the bit rate to ensure that the content is played at the optimal bit rate for the current network connection.

You can set the adaptive bit-rate (ABR) switching policy and the initial, minimum, and maximum bit rates for a multiple-bit-rate (MBR) stream. TVSDK automatically switches to the bit rate that provides the best playback experience in the specified configuration.

Keep the following information in mind:

• TVSDK does not dispatch events from bit-rate switching.
• You can change your ABR settings at any time, and the player switches to use the profile that most closely matches the most recent settings.

For example, if a stream has the following profiles:

• 1: 300000
• 2: 700000
• 3: 1500000
• 4: 2400000
• 5: 4000000

If you specify a range of 300000 to 2000000, TVSDK considers only profiles 1, 2 and 3. This allows applications to adjust to various network conditions, such as switching from WiFi to 3G or to various devices such as a phone, a tablet, or a desktop computer.

Configure adaptive bit rates

To configure TVSDK adaptive bit-rate parameters:

1. Configure an instance of PTABRControlParameters to set the initial, minimum, and maximum bit-rate settings.

   The default values are displayed in the following code snippet, but your application can set any integer value for each of these parameters.

   IMPORTANT

   Specify the bit-rate settings in bits-per-second (bps).

   // ARC (add autorelease for non-ARC)
   PTABRControlParameters *abrMetaData =
       [[PTABRControlParameters alloc] init];
   
   abrMetaData.initialBitRate = -1;
   abrMetaData.minBitRate = 0;
   abrMetaData.maxBitRate = INT_MAX;
   

2. Update your PTMediaPlayer instance with the configured PTABRControlParameters instance.

   // assuming self.player is the PTMediaPlayer instance
   self.player.abrControlParameters = abrMetaData;
   

Remember the following:

• The application must set the abrControlParameters property on PTMediaPlayer before configuring a PTMediaPlayerItem instance for the initial and minimum bitrate settings to take effect.

  After content playback starts, setting a new instance only affects the maximum bitrate setting.

• To update the maximum bitrate setting during playback, create a new PTABRControlParameters instance and set it on the player instance.

• You can update the maximum bitrate setting during playback only on iOS 8.0 and later. For earlier versions, the maxBitrate value that was set before content playback started is used.