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Enabling Video Synchronization Feature

What is NexPlayer's synchronization feature?

NexPlayer synchronization feature technology allows you to sync the video arrival and stream video synchronously across different devices using the DASH SPD value. This is also possible for HLS streams by controlling the SPD value from the client-side.

How to enable synchronization feature in the sample application

To get started, we need an apk and at least two devices. Steps to enable Synchronization:

  • Go to the three dots → Settings → SPD Settings.

Here we have several fields that, depending on our needs, we will have to configure.

SPD: Enabled (this field is used to enable and disable SPD).

  • Note: The other fields will be enabled when you enable the SPD option.

SPD Delay Time: Value between 500.0 ms and 20,000.0ms (default 2000.0ms).

**SPD Sync Range: Value between 100.0 ms and 2000.0ms (default 300.0ms).

SPD Too Much Difference Time: Value between 2000.0and 10,000.0 ms (default 5000.0ms).

Sync to Device UTC: Enable or disable. This field takes as reference the UTC time (disabled by default).

Once we have configured what we need, we will play the content with SPD in the section.

Streaming → GO TO URL (at the bottom) → put the URL in the “Stream URL

Limitations

  • Only works with live content.
  • Device time should be adjusted correctly, incorrect device time or setting it manually might break the logic. This can be handled by using server time but the synchronisation won’t be precise as device time as server time is given in seconds, not in milliseconds as device time.
  • Setting a very low SPD value for the stream might affect smooth playback experience as it won’t allow the player to create enough buffer.
  • Synchronization feature is highly dependent on the internet speed and the configuration of the manifest.

How to enable synchronization feature from the code

NexPlayer synchronization can be enabled by setting the following property:

mNexPlayer.setProperty(NexPlayer.NexProperty.ENABLE_SPD_SYNC_TO_GLOBAL_TIME, 1);

To set the SPD value from the client-side for both DASH and HLS you can set the SPD value per property ( SET_PRESENTATION_DELAY or 590) as shown below:

mNexPlayer.setProperty (NexProperty.SET_PRESENTATION_DELAY,mPrefData.mSPDValue);

Note that if the value of SET_PRESENTATION_DELAY is too large, the player may not find the delayed segment provided by the live content server.

Advanced configuration

You can control the synchronization behaviour further by adjusting the below properties.

ENABLE_SPD_SYNC_TO_DEVICE_TIME

Enables synchronization to device UTC for more accurate behaviour.

mNexPlayer.setProperty(NexPlayer.NexProperty.ENABLE_SPD_SYNC_TO_DEVICE_TIME, 1);

  • Default: 0

  • Values:

  • 0: Disabled device UTC

  • 1: Enabled device UTC

SET_SPD_SYNC_DIFF_TIME

If the current playback desynchronizes from the value, the player will slow down or speed up in order to re-synchronize.

mNexPlayer.setProperty(NexPlayer.NexProperty.SET_SPD_SYNC_DIFF_TIME, 100);

  • Unit: msec (1/1000 sec)

  • Default: 300 (300 msec)

SET_SPD_TOO_MUCH_DIFF_TIME

If playback is out of sync than this value, the player will jump to synchronize the video rather than make it by speeding.

mNexPlayer.setProperty(NexPlayer.NexProperty.SET_SPD_TOO_MUCH_DIFF_TIME,5000);

  • Unit: msec (1/1000 sec)

  • Default: 5000 (5 seconds)