* Media init segment support
Resolve EXT-X-MAP URI information in the playlist loader. Add support for requesting and appending initialization segments to the segment loader.
* Basic support for fragmented MP4 playback
Re-arrange source updater and track support to fit our design goals more closely. Make adjustments so that the correct source buffer types are created when a fragmented mp4 is encountered. This version will play Apple's fMp4 bipbop stream but you have to seek the player to 10 seconds after starting because the first fragment starts at 10, not 0.
* Finish consolidating audio loaders
Manage a single pair of audio playlist and segment loaders, instead of one per track. Update track logic to work with the new flow.
* Detect and set the correct starting timestamp offset
Probe the init and first MP4 segment to correctly set timestamp offset so that the stream begins at time zero. After this change, Apple's fragmented MP4 HLS example stream plays without additional modification.
* Guard against media playlists without bandwidth information
If a media playlist is loaded directly or bandwidth info is unavailable, make sure the lowest bitrate check doesn't error. Add some unnecessary request shifting to tests to avoid extraneous requests caused by the current behavior of segment loader when abort()-ing THEN pause()-ing.
* Add stub prog_index.m3u8 for tests
Some of the tests point to master playlists that reference prog_index.m3u8. Sinon caught most of the exceptions related to this but the tests weren't really exercising realistic scenarios. Add a stub prog_index to the test fixtures so that requests for prog_index don't unintentionally error.
* Abort init segment XHR alongside other segment XHRs
If the segment loader XHRs are aborted, stop the init segment one as well. Make sure to check the right property for the init segment XHR before continuing the loading process. Make sure falsey values do not cause a playlist to be blacklisted in FF for audio info changes.
* Fix audio track management after reorganization
Delay segment loader initialization steps until all starting configuration is ready. This allowed source updater MIME types to be specified early without triggering the main updater to have its audio disabled on startup. Tweak the mime type identifier function to signal alternate audio earlier. Move `this` references in segment loader's checkBuffer_ out to stateful functions to align with the original design goals. Removed a segment loader test that seemed duplicative after the checkBuffer_ change.
* Fix D3 on stats page
Update URL for D3. Remove audio switcher since it's included by default now.
* Only override codec defaults if an actual value was parsed
When converting codec strings into MIME type configurations for source buffers, make sure to use default values if the codec string didn't supply particular fields. Export the codec to MIME helper function so it can be unit-tested.
* IE fixes
Array.prototype.find() isn't available in IE so use .filter()[0] instead.
* Blacklist unsupported codecs
If MediaSource.isTypeSupported fails in a generic MP4 container, swapping to a variant with those codecs is unlikely to be successful. For instance, the fragmented bip-bop stream includes AC-3 and EC-3 audio which is not supported on Chrome or Firefox today. Exclude variants with codecs that don't pass the isTypeSupported test.
David LaPalomento
bbf47741cc