Exception with ClippingMediaSource on encrypted HLS

[rajab57]

Issue description

Exception for a clipped HLS Video with AES-128 encryption.
When playing as a mediaSource, the video plays fine, but when clipped using ClippingMediaSource throws an exception

com.google.android.exoplayer2.source.ClippingMediaSource$IllegalClippingException
 at com.google.android.exoplayer2.source.ClippingMediaSource$ClippingTimeline.<init>(ClippingMediaSource.java:217)
 at com.google.android.exoplayer2.source.ClippingMediaSource.onChildSourceInfoRefreshed(ClippingMediaSource.java:180)
 at com.google.android.exoplayer2.source.ClippingMediaSource.onChildSourceInfoRefreshed(ClippingMediaSource.java:37)
 at com.google.android.exoplayer2.source.CompositeMediaSource$1.onSourceInfoRefreshed(CompositeMediaSource.java:99)
 at com.google.android.exoplayer2.source.hls.HlsMediaSource.onPrimaryPlaylistRefreshed(HlsMediaSource.java:392)
 at com.google.android.exoplayer2.source.hls.playlist.HlsPlaylistTracker.onPlaylistUpdated(HlsPlaylistTracker.java:376)
 at com.google.android.exoplayer2.source.hls.playlist.HlsPlaylistTracker.access$1000(HlsPlaylistTracker.java:41)
 at com.google.android.exoplayer2.source.hls.playlist.HlsPlaylistTracker$MediaPlaylistBundle.processLoadedPlaylist(HlsPlaylistTracker.java:587)
 at com.google.android.exoplayer2.source.hls.playlist.HlsPlaylistTracker$MediaPlaylistBundle.onLoadCompleted(HlsPlaylistTracker.java:534)
 at com.google.android.exoplayer2.source.hls.playlist.HlsPlaylistTracker$MediaPlaylistBundle.onLoadCompleted(HlsPlaylistTracker.java:461)
 at com.google.android.exoplayer2.upstream.Loader$LoadTask.handleMessage(Loader.java:377)
 at android.os.Handler.dispatchMessage(Handler.java:102)
 at android.os.Looper.loop(Looper.java:148)
 at android.os.HandlerThread.run(HandlerThread.java:61)

Reproduction steps

MediaSource mediaSource = new ClippingMediaSource(mediaSources[0], 5000000, 25000000, true); Made this change in PlayerActivity.java in the Exoplayer demo app

Version of ExoPlayer being used

2.7.0

Device(s) and version(s) of Android being used

Nexus 6P Android 8.0.0
Nexus 5 Android 6.0.1 API 23

Link to test content

sent to dev.exoplayer@gmail.com

BugReport

sent to dev.exoplayer@gmail.com

[ojw28]

This happens when the HLS media playlists contain a EXT-X-PROGRAM-DATE-TIME, and is a result of restrictions that ClippingMediaSource has around what type of content it's able to clip.

@andrewlewis - I wonder whether it would be possible to relax the ClippingMediaSource requirement that the single period needs to start at the beginning of its parent window? Also, should we set message on IllegalClippingExceptions that includes the reason value?

[rajab57]

@ojw28
Is there documentation what the restrictions are in the content that ClippingMediaSource can clip ?

[ojw28]

As per the ClippingMediaSource documentation here:

The wrapped source must consist of a single period that starts at the beginning of the corresponding window.

The problem is more that it's not obvious a HlsMediaSource will violate this requirement when the media playlists contain EXT-X-PROGRAM-DATE-TIME. It's pretty hard to document this kind of thing in a clear way. We'd be better off just relaxing the restriction, as per my question to @andrewlewis above.

[andrewlewis]

@rajab57 38914f0 removes the restriction on clipping child sources that have an offset window and adds a message to clipping errors to make the error more obvious, and, in addition, in 4373e63 we've also changed HLS timelines so that the period and window both start from zero when first loading the stream. Please try this out on the development branch and let us know if there are any problems with the fixes. Thanks!

[rajab57]

@andrewlewis Works !!
Thanks

[ojw28]

This was also fixed (independently) by 4373e63. In other words, either 38914f0 or 4373e63 fix this issue. We'll be picking up 4373e63 in our next release (2.7.1).

[rajab57]

@ojw28
With more testing, noticing this issue #3966

[ojw28]

Our planned 2.7.1 release (https://github.com/google/ExoPlayer/tree/dev-v2-r2.7.1) should fix this issue without causing #3966, so I think that release will be fine. We'll also be fixing #3966 in the dev-v2 branch shortly.