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Bug 856361. Part 7: Fix copying of track data from input streams to output streams in TrackUnionStream. r=padenot

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--HG--
extra : rebase_source : 7138200b4f1060de00b2410f58c645c353580a6f
This commit is contained in:
Robert O'Callahan 2013-08-01 16:02:49 +12:00
parent a8588cd799
commit 0aeb871775
1 changed files with 70 additions and 9 deletions
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79
content/media/TrackUnionStream.h
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@ -120,6 +120,17 @@ protected:
// Only non-ended tracks are allowed to persist in this map.
struct TrackMapEntry {
// mEndOfConsumedInputTicks is the end of the input ticks that we've consumed.
// 0 if we haven't consumed any yet.
TrackTicks mEndOfConsumedInputTicks;
// mEndOfLastInputIntervalInInputStream is the timestamp for the end of the
// previous interval which was unblocked for both the input and output
// stream, in the input stream's timeline, or -1 if there wasn't one.
StreamTime mEndOfLastInputIntervalInInputStream;
// mEndOfLastInputIntervalInOutputStream is the timestamp for the end of the
// previous interval which was unblocked for both the input and output
// stream, in the output stream's timeline, or -1 if there wasn't one.
StreamTime mEndOfLastInputIntervalInOutputStream;
MediaInputPort* mInputPort;
// We keep track IDs instead of track pointers because
// tracks can be removed without us being notified (e.g.
@ -161,6 +172,9 @@ protected:
(long long)outputStart));
TrackMapEntry* map = mTrackMap.AppendElement();
map->mEndOfConsumedInputTicks = 0;
map->mEndOfLastInputIntervalInInputStream = -1;
map->mEndOfLastInputIntervalInOutputStream = -1;
map->mInputPort = aPort;
map->mInputTrackID = aTrack->GetID();
map->mOutputTrackID = track->GetID();
@ -208,14 +222,12 @@ protected:
// Ticks >= startTicks and < endTicks are in the interval
StreamTime outputEnd = GraphTimeToStreamTime(interval.mEnd);
TrackTicks startTicks = outputTrack->GetEnd();
#ifdef DEBUG
StreamTime outputStart = GraphTimeToStreamTime(interval.mStart);
#endif
NS_ASSERTION(startTicks == TimeToTicksRoundUp(rate, outputStart),
"Samples missing");
TrackTicks endTicks = TimeToTicksRoundUp(rate, outputEnd);
TrackTicks ticks = endTicks - startTicks;
// StreamTime inputStart = source->GraphTimeToStreamTime(interval.mStart);
StreamTime inputStart = source->GraphTimeToStreamTime(interval.mStart);
StreamTime inputEnd = source->GraphTimeToStreamTime(interval.mEnd);
TrackTicks inputTrackEndPoint = TRACK_TICKS_MAX;
@ -239,12 +251,61 @@ protected:
// that 'ticks' samples are gathered, even though a tick boundary may
// occur between outputStart and outputEnd but not between inputStart
// and inputEnd.
// We'll take the latest samples we can.
TrackTicks inputEndTicks = TimeToTicksRoundUp(rate, inputEnd);
TrackTicks inputStartTicks = inputEndTicks - ticks;
segment->AppendSlice(*aInputTrack->GetSegment(),
std::min(inputTrackEndPoint, inputStartTicks),
std::min(inputTrackEndPoint, inputEndTicks));
// These are the properties we need to ensure:
// 1) Exactly 'ticks' ticks of output are produced, i.e.
// inputEndTicks - inputStartTicks = ticks.
// 2) inputEndTicks <= aInputTrack->GetSegment()->GetDuration().
// 3) In any sequence of intervals where neither stream is blocked,
// the content of the input track we use is a contiguous sequence of
// ticks with no gaps or overlaps.
if (map->mEndOfLastInputIntervalInInputStream != inputStart ||
map->mEndOfLastInputIntervalInOutputStream != outputStart) {
// Start of a new series of intervals where neither stream is blocked.
map->mEndOfConsumedInputTicks = TimeToTicksRoundDown(rate, inputStart) - 1;
}
TrackTicks inputStartTicks = map->mEndOfConsumedInputTicks;
TrackTicks inputEndTicks = inputStartTicks + ticks;
map->mEndOfConsumedInputTicks = inputEndTicks;
map->mEndOfLastInputIntervalInInputStream = inputEnd;
map->mEndOfLastInputIntervalInOutputStream = outputEnd;
// Now we prove that the above properties hold:
// Property #1: trivial by construction.
// Property #3: trivial by construction. Between every two
// intervals where both streams are not blocked, the above if condition
// is false and mEndOfConsumedInputTicks advances exactly to match
// the ticks that were consumed.
// Property #2:
// Let originalOutputStart be the value of outputStart and originalInputStart
// be the value of inputStart when the body of the "if" block was last
// executed.
// Let allTicks be the sum of the values of 'ticks' computed since then.
// The interval [originalInputStart/rate, inputEnd/rate) is the
// same length as the interval [originalOutputStart/rate, outputEnd/rate),
// so the latter interval can have at most one more integer in it. Thus
// TimeToTicksRoundUp(rate, outputEnd) - TimeToTicksRoundUp(rate, originalOutputStart)
// <= TimeToTicksRoundDown(rate, inputEnd) - TimeToTicksRoundDown(rate, originalInputStart) + 1
// Then
// inputEndTicks = TimeToTicksRoundDown(rate, originalInputStart) - 1 + allTicks
// = TimeToTicksRoundDown(rate, originalInputStart) - 1 + TimeToTicksRoundUp(rate, outputEnd) - TimeToTicksRoundUp(rate, originalOutputStart)
// <= TimeToTicksRoundDown(rate, originalInputStart) - 1 + TimeToTicksRoundDown(rate, inputEnd) - TimeToTicksRoundDown(rate, originalInputStart) + 1
// = TimeToTicksRoundDown(rate, inputEnd)
// <= inputEnd/rate
// (now using the fact that inputEnd <= track->GetEndTimeRoundDown() for a non-ended track)
// <= TicksToTimeRoundDown(rate, aInputTrack->GetSegment()->GetDuration())/rate
// <= rate*aInputTrack->GetSegment()->GetDuration()/rate
// = aInputTrack->GetSegment()->GetDuration()
// as required.
if (inputStartTicks < 0) {
// Data before the start of the track is just null.
segment->AppendNullData(-inputStartTicks);
inputStartTicks = 0;
}
if (inputEndTicks > inputStartTicks) {
segment->AppendSlice(*aInputTrack->GetSegment(),
std::min(inputTrackEndPoint, inputStartTicks),
std::min(inputTrackEndPoint, inputEndTicks));
}
LOG(PR_LOG_DEBUG+1, ("TrackUnionStream %p appending %lld ticks of input data to track %d",
this, (long long)(std::min(inputTrackEndPoint, inputEndTicks) - std::min(inputTrackEndPoint, inputStartTicks)),
outputTrack->GetID()));