Multikey DRM - Allow restoring multiple keysets for offline playbacks

[calweaver]

No description provided.

[calweaver]

Hi Guys,

Been working on this issue for a week or so, hoping somebody can point me in the right direction.

We have sucessfully got Exoplayer playing back Widevine encrypted content with offline keys (ie using the offLicenseHelper and offlineLicenseKeySetid) when the video and audio stream both have the same key.

When we use different keys for the video and the audio stream we get the attached error.

We can playback content that uses seperate keys for video and audio Ok when not using the offlineLicenseKeySetId, ie allowing exoplayer to fetch the widevine keys at start of play.

ie if we remove this line of code,
drmSessionManager.setMode(DefaultDrmSessionManager.MODE_DOWNLOAD,oflineLicenseKeySetId);

The DefaultDrmSessionManager is created with multiSession: true

thanks

[andrewlewis]

Please could you provide a full bug report as requested in the issue template?

[ojw28]

This is related to #3780, although keeping it as separate issue because this one relates specifically to offline. Some notes that should help clarify the current situation:

• The existing ExoPlayer implementation can already support multi-key content, both within and across adaptation sets, without the need to set multiSession = true when instantiating a DefaultDrmSessionManager, and for both streaming and offline. However this depends on the license server responding with all of the keys required to play the content when provided with a request that contains the PSSH for one of the streams. See Multikey protected Dash video doesn't work #3780 and Playback of Axinom multi-key DASH does not request all keys from license server #1824 for some more background. This is how several of the big streaming providers I'm aware of do things and is efficient from the client's perspective, however as noted on Multikey protected Dash video doesn't work #3780 it's no longer in line with DASH-IF recommendations for a client to assume the license server will behave in this way. Despite this, if you are able to configure your license server to behave as described then this offers the best short term solution to your problem.
• If the license server does not behave as described above then for streaming it's necessary to set multiSession = true to handle different keys for audio and video streams. Multikey protected Dash video doesn't work #3780 is tracking making sure that we also support seamless adaptation for different keys within an adaptation set (e.g. HD vs SD video).
• If the license server does not behave as described above then for offline we just don't have the code necessary to support the user case yet. It would be necessary to offline multiple key sets (each of which would have its own keySetId, and make sure that they get loaded into the correct session during offline playback We'll use this issue to track adding support for this case.