Automatically fallback to Widevine L3 in case there is a DRM error

[REQUIRED] Use case description

Recently some devices had their Widevine L1 license revoked (see #7986, #8075). This causes the affected devices to be unable to play DRM content by default, because ExoPlayer will attempt to use L1 (since the device claims to support it), which will fail (since the device had its license revoked).

Proposed solution

ExoPlayer should have an option to automatically retry playback with L3 (if the DRM license allows it) instead of throwing a DRM-related exception. Only if playback was also unsuccessful with L3 should an error be thrown.

Alternatives considered

• Implement this fallback mechanism directly in the app. It would be nice though if ExoPlayer offered this out of the box.
• Include the affected devices in needsForceWidevineL3Workaround(). However, this list would have to be manually kept up to date, and it would not cover devices with similar issues that have yet to be discovered.

[icbaker]

Is it possible to manually override the Widevine security level based on device model?

You can force the device to use L3 by setting the “securityLevel” property to “L3” on the underlying MediaDrm object (like this).

You can achieve this from ExoPlayer by writing a custom ExoMediaDrm.Provider (you can probably delegate to FrameworkMediaDrm.DEFAULT_PROVIDER) that mutates the ExoMediaDrm object inside Provider#acquireExoMediaDrm() by calling the ExoMediaDrm#setPropertyString() method. You probably only want to do this if uuid is C.WIDEVINE_UUID.

You can wire up this custom provider by passing it to DefaultDrmSessionManager.Builder#setUuidAndExoMediaDrmProvider.

If you always set this property then (obviously?) L1 content won’t play correctly.

[icbaker]

I’m tracking the work to allow specifying a custom MediaSourceDrmHelper in #8466.