1062101 - The mDuration field of VideoData in MediaSourceReader::OnVideoDecoded is incorrect with WebM

Status: RESOLVED FIXED

(Core :: Audio/Video, defect)

Description

[cajbir (:cajbir)]

If a SourceBufferDecoder reaches the end of its data then the associated WebMReader uses GetMediaEndTime to compute the sample duration, taking that time as the time of the next sample.

SourceBufferDecoder::GetMediaEndTime returns the duration of the resource which results in the computed sample time being incorrect. 

Is it safe to change GetMediaEndTime to return the time of the last item in the buffered data for the SourceBufferDecoder? Or do we change WebMReader's behaviour here.

Comment 2

[Matthew Gregan [:kinetik]]

Not sure how I managed that, but I posted bug 1061402's comment here and this bug's comment there.  Made it private to avoid confusion.  Intended comment:

As far as I can tell, GetEndMediaTime is only used by the WebMReader.  I think it's confusing given the existence of GetMediaDuration.  My preference is to remove it entirely, and compute the last frame duration in WebMReader using the Δt between the current and previous frame as the frame duration.

Comment 3

[Matthew Gregan [:kinetik]]

Attachment: Compute WebM frame duration from Δt of last frame.

Proposed fix.

Comment 4

[Matthew Gregan [:kinetik]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/b83d8447aaaa

Comment 5

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/b83d8447aaaa