private uint SampleCountInLastBatch = 0; // last batch sample count for this trak box (this is independent of the other trak box)
/// <summary>
/// InitSampleTableBoxFromStreamLocations
/// Initialize the boxes that point to where the payload bits are, without writing them out to final destination file yet.
/// Major change (06/06/2012): favor creating new chunks over accumulating slices in a chunk.
/// We take it to the extreme here, like VLC does it: we create a new chunk for every slice/sample.
/// What this does is make the stsc box small, but the stco box very large. The advantage is that
/// every slice now has an offset into mdat (and the slice crawler can't possibly go out of sync).
/// </summary>
/// <param name="streamLocations">List of StreamDataBlockInfo extracted from source stream, possibly using InitSampleStreamFromSampleTableBox above.</param>
public void InitSampleTableBoxFromStreamLocations(List <StreamDataBlockInfo> streamLocations, ref ulong currMdatOffset)
{
// if this is the first call, create temp files
if (SttsCountsWriter == null)
{
CreateTempFiles();
}
if (CompositionTimeToSample == null && (CTTSOut) && (streamLocations.Any(d => (d.CTS > 0UL) || (d.SliceType == SliceType.BFrame))))
{
CompositionTimeToSample = new CompositionTimeToSample(this);
}
if (streamLocations.Count == 0)
{
throw new Exception("InitSampleTableBoxFromStreamLocations: SampleStreamLocations list empty.");
}
bool needNewChunk = true;
foreach (StreamDataBlockInfo sample in streamLocations)
{
uint scaledDuration = (uint)TimeArithmetic.ConvertToTimeScale(parent.parent.MediaHeaderBox.TimeScale, sample.SliceDuration);
if (LastDuration == 0)
{
sampleCountInStts = 1;
}
else if (LastDuration == scaledDuration)
{
sampleCountInStts++;
}
else
{
WriteToSttsTempFile();
sampleCountInStts = 1; // this one for which duration is different counts as one
}
LastDuration = scaledDuration;
//TimeTicks += sample.SliceDuration;
if (sample.SliceType == SliceType.IFrame)
{
SyncSampleMapWriter.Write(SampleIndex); // if the SyncSampleMapStream has zero length when all is done, then its box should be null
CurrSyncSampleMapCount++;
}
// compute CTTS from TimeStamp and CTS
if (CompositionTimeToSample != null)
{
// CTS = Composition Time of the Sample, so these values are ever-increasing
// CTTS = Composition Time relative to Time of the Sample, so these are really either 0 or some multiple of the typical sample duration
// CTTS values for an i-frame, for example, is always zero, as its composition time relative to the sample:
// CTTS-iframe = SampleTime - CTS = Always 0
if (sample.SliceType == SliceType.IFrame)
{
// relative time for an iframe is always 0
CompositionTimeToSample.AddEntry(0);
LastSynchTime = 0;
}
else
{
//if (sample.TimeStampNew.HasValue) {
// // relative time for a d-frame is always 0
// uint TimeFromLastSample = (uint)TimeArithmetic.ConvertToTimeScale(parent.parent.MediaHeaderBox.TimeScale, sample.SliceDuration);
// CompositionTimeToSample.AddEntry((uint)TimeFromLastSample);
//} else {
// // this means we are a b-frame
// CompositionTimeToSample.AddEntry((uint)uint.MaxValue);
//}
if (!sample.TimeStampNew.HasValue || sample.SliceType == SliceType.BFrame)
{
// this means we are a b-frame
uint TimeFromLastSample = (uint)TimeArithmetic.ConvertToTimeScale(parent.parent.MediaHeaderBox.TimeScale, sample.SliceDuration);
// we get further from a sync time for each consecutive b-frame we have
// as you can see above if we encounter an i or d frame we snap back to a delta of 0
LastSynchTime += TimeFromLastSample;
CompositionTimeToSample.AddEntry((uint)LastSynchTime);
}
else if (sample.TimeStampNew.HasValue)
{
// relative time for a d-frame is always 0
CompositionTimeToSample.AddEntry(0);
LastSynchTime = 0;
}
}
}
// determine which chunk to put this sample in
SampleSizeWriter.Write((uint)sample.SliceSize);
SampleToChunkBox.SetFileOffsetForChunk(SampleIndex, (uint)sample.SliceSize, 1u /* (uint)streamLocations.Count */, needNewChunk, ref currMdatOffset);
needNewChunk = true; // always create a new chunk, thereby having only a single slice in every chunk (as in VLC output)
SampleIndex++;
}
// set last count
SampleCountInLastBatch = (uint)streamLocations.Count;
}
