Implement fast forward and rewind

When users fast forward or fast rewind through the media, they are in the trick play mode. To enter trick play mode, you need to set the MediaPlayer playback rate to a value other than 1.

To switch the speed, you must set one value.

1. Move from normal play mode (1x) to trick play mode by setting the rate on the MediaPlayer to an allowed value.

   • The MediaPlayerItem class defines the allowed playback rates.

   • Browser TVSDK selects the closest allowed rate if the specified rate is not allowed.

     The following example function sets the rate:

     setTrickPlayRate = function (player, trickPlayRate) {
                   player.rate = trickPlayRate;
     }
     

     The following example function can be used to query the available playback rates:

     getAvailableTrickPlayRates = function (player) {
              var item = player.currentItem;
              var availableRates = item. availablePlaybackRates;
              return availableRates;
     }
     
     

2. You can optionally listen for rate-change events, which let you know when you requested a rate change and when a rate change actually happens.

   Browser TVSDK dispatches the following events related to trick play:
   

   • AdobePSDK.PSDKEventType.RATE_SELECTED when the rate value changes to a different value.

   • AdobePSDK.PSDKEventType.RATE_PLAYING when playback resumes at the selected rate.

     Browser TVSDK dispatches both of these events when the player returns from trick-play mode to normal play mode.

Rate-change API elements

Browser TVSDK includes methods, properties, and events to determine valid rates, current rates, whether trick play is supported, and other functionality related to fast forward and rewind.

Use the following API elements to change play rates:

• MediaPlayer.rate

• PlaybackRateEvent.rate

• MediaPlayerItem.istrickPlaySupported

• MediaPlayerItem.availablePlaybackRates - specifies valid rates.

  Rate value	Effect on playback
  2.0, 4.0, 8.0, 16.0, 32.0, 64.0	Switches to fast-forward mode with the specified multiplier faster than normal (for example, 4 is 4 times faster than normal)
  -2.0, -4.0, -8.0, -16.0, -32.0, -64.0	Switches to fast-rewind mode
  1.0	Switches to normal play mode (calling play is the same as setting the rate property to 1.0)
  0.0	Pauses (calling pause is the same as setting the rate property to 0.0)

Limitations and behavior for trick-play

There are some limitations and some issues in the way trick play mode behaves.

Here is a list of the trick-play mode limitations:

• If the stream does not contain a trick play adaptation, fast rewind is disabled, and maximum play rate for fast forward is limited to 8.

• When trick play adaptations are used to provide the trick mode, the audio track is disabled.

• In trick play mode, the switching of audio and closed captions tracks is disabled.

• Play and pause are enabled.

• On seek, if playback is in trick play mode, playback rate is set to 1 and normal playback resumes.

• The adaptive bit rate (ABR) logic is enabled.

  When using normal adaptations the profiles are restricted between ABRControlParameters.minBitRate and ABRControlParameters.maxBitRate. When using trick play adaptations, the profiles are restricted between ABRControlParameters.minTrickPlayBitRate and ABRControlParameters.maxTrickPlayBitRate.

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