Use audio clock as the reference media clock
o Only do this for realtime applications
o Adjust other track clock based on audio clock
o Assume other track uses wall clock as the media clock
o Use some heuristics to reduce the size of stts box by 2/3.
- also
o Remove one unused key from MetaData.h
Change-Id: Ib9432842627b61795b533508158c25258a527332
diff --git a/include/media/stagefright/MPEG4Writer.h b/include/media/stagefright/MPEG4Writer.h
index 2e1e8d8..be96935 100644
--- a/include/media/stagefright/MPEG4Writer.h
+++ b/include/media/stagefright/MPEG4Writer.h
@@ -128,6 +128,12 @@
// Write the first chunk from the given ChunkInfo.
void writeFirstChunk(ChunkInfo* info);
+ // Adjust other track media clock (presumably wall clock)
+ // based on audio track media clock with the drift time.
+ int64_t mDriftTimeUs;
+ void addDriftTimeUs(int64_t driftTimeUs);
+ int64_t getDriftTimeUs();
+
void lock();
void unlock();
diff --git a/include/media/stagefright/MetaData.h b/include/media/stagefright/MetaData.h
index ab1fa4f..43354c2 100644
--- a/include/media/stagefright/MetaData.h
+++ b/include/media/stagefright/MetaData.h
@@ -86,10 +86,10 @@
// Track authoring progress status
// kKeyTrackTimeStatus is used to track progress in elapsed time
- // kKeyTrackFrameStatus is used to track progress in authored frames
- kKeyTrackFrameStatus = 'tkfm', // int32_t
kKeyTrackTimeStatus = 'tktm', // int64_t
+ kKeyNotRealTime = 'ntrt', // bool (int32_t)
+
};
enum {
diff --git a/media/libstagefright/MPEG4Writer.cpp b/media/libstagefright/MPEG4Writer.cpp
index 1460f37..9fe3864 100644
--- a/media/libstagefright/MPEG4Writer.cpp
+++ b/media/libstagefright/MPEG4Writer.cpp
@@ -72,6 +72,11 @@
bool mIsAudio;
bool mIsMPEG4;
int64_t mTrackDurationUs;
+
+ // For realtime applications, we need to adjust the media clock
+ // for video track based on the audio media clock
+ bool mIsRealTimeRecording;
+ int64_t mMaxTimeStampUs;
int64_t mEstimatedTrackSizeBytes;
int64_t mMaxWriteTimeUs;
int32_t mTimeScale;
@@ -940,6 +945,7 @@
mDone = false;
mIsFirstChunk = true;
+ mDriftTimeUs = 0;
for (List<Track *>::iterator it = mTracks.begin();
it != mTracks.end(); ++it) {
ChunkInfo info;
@@ -967,6 +973,14 @@
startTimeUs = 0;
}
+ mIsRealTimeRecording = true;
+ {
+ int32_t isNotRealTime;
+ if (params && params->findInt32(kKeyNotRealTime, &isNotRealTime)) {
+ mIsRealTimeRecording = (isNotRealTime == 0);
+ }
+ }
+
initTrackingProgressStatus(params);
sp<MetaData> meta = new MetaData;
@@ -1326,6 +1340,10 @@
uint32_t previousSampleSize = 0; // Size of the previous sample
int64_t previousPausedDurationUs = 0;
int64_t timestampUs;
+
+ int64_t wallClockTimeUs = 0;
+ int64_t lastWallClockTimeUs = 0;
+
sp<MetaData> meta_data;
bool collectStats = collectStatisticalData();
@@ -1429,6 +1447,33 @@
}
timestampUs -= previousPausedDurationUs;
+ if (mIsRealTimeRecording && !mIsAudio) {
+ // The minor adjustment on the timestamp is heuristic/experimental
+ // We are adjusting the timestamp to reduce the fluctuation of the duration
+ // of neighboring samples. This in turn helps reduce the track header size,
+ // especially, the number of entries in the "stts" box.
+ if (mNumSamples > 1) {
+ int64_t durationUs = timestampUs + mOwner->getDriftTimeUs() - lastTimestampUs;
+ int64_t diffUs = (durationUs > lastDurationUs)
+ ? durationUs - lastDurationUs
+ : lastDurationUs - durationUs;
+ if (diffUs <= 5000) { // XXX: Magic number 5ms
+ timestampUs = lastTimestampUs + lastDurationUs;
+ } else {
+ timestampUs += mOwner->getDriftTimeUs();
+ }
+ }
+ }
+ CHECK(timestampUs >= 0);
+ if (mNumSamples > 1) {
+ if (timestampUs <= lastTimestampUs) {
+ LOGW("Drop a frame, since it arrives too late!");
+ copy->release();
+ copy = NULL;
+ continue;
+ }
+ }
+
LOGV("time stamp: %lld and previous paused duration %lld",
timestampUs, previousPausedDurationUs);
if (timestampUs > mTrackDurationUs) {
@@ -1454,6 +1499,14 @@
}
lastDurationUs = timestampUs - lastTimestampUs;
lastTimestampUs = timestampUs;
+ if (mIsRealTimeRecording && mIsAudio) {
+ wallClockTimeUs = systemTime() / 1000;
+ int64_t wallClockDurationUs = wallClockTimeUs - lastWallClockTimeUs;
+ if (mNumSamples > 2) {
+ mOwner->addDriftTimeUs(lastDurationUs - wallClockDurationUs);
+ }
+ lastWallClockTimeUs = wallClockTimeUs;
+ }
if (isSync != 0) {
mStssTableEntries.push_back(mNumSamples);
@@ -1679,6 +1732,18 @@
}
}
+void MPEG4Writer::addDriftTimeUs(int64_t driftTimeUs) {
+ LOGV("addDriftTimeUs: %lld us", driftTimeUs);
+ Mutex::Autolock autolock(mLock);
+ mDriftTimeUs += driftTimeUs;
+}
+
+int64_t MPEG4Writer::getDriftTimeUs() {
+ LOGV("getDriftTimeUs: %lld us", mDriftTimeUs);
+ Mutex::Autolock autolock(mLock);
+ return mDriftTimeUs;
+}
+
void MPEG4Writer::Track::bufferChunk(int64_t timestampUs) {
LOGV("bufferChunk");
