This is important for seeking Opus tracks, as Opus needs to decode a
certain amount of input data before its output converges. Without this,
audio after a seek can sound muffled briefly.
We don't need to put these in a union, it's not gonna save us much
space. The reader also may find both audio and video elements, in which
case this code would produce undefined behavior.
Also, with this change, we can use the default values from the spec.
Otherwise, if the sample iterator resides in a block with multiple
frames before the seek, the demuxer will output all the remaining
frames from that block before moving on to the block at the seeked
position.
This allows us to read WebM files that have blocks with additional data
attached to each block for an alpha frame. For now, only the main coded
data is used, the additional data containing the alpha channel is
ignored.
By default, MatroskaDemuxer chooses not to seek if the current frame
is closer to the seek target than the keyframe that precedes the seek
target. However, it can be desirable to seek to a keyframe anyway, so
let's allow that.
Reader::seek_to_random_access_point() isn't actually guaranteed to
return a sample iterator that has already gotten a block timestamp.
This verify passes in almost every case, but if we happen to seek to a
timestamp before the second keyframe, we'd crash.
There was a warning for the Optional initializer having no effect, but
removing the initializer caused the call to add a track to the HashMap
to complain. A constructor looks a little nicer here anyway.
Most users will only care about the total file duration, and shouldn't
be required to determine the file duration from multiple track
durations. To facilitate that, add a total_duration() function that
returns the demuxer's duration not associated to any particular track.
This first pass only applies to the following two cases:
- Public functions returning a view type into an object they own
- Public ctors storing a view type
This catches a grand total of one (1) issue, which is fixed in
the previous commit.
