// The video track is the track to which all other tracks should sync with.
// SyncPoints are instances in time at which:
// 1. the current video slice is an IFrame; or
// 2. the current video slice is the beginning of a new block (in case the video track is all IFrames or no IFrames).
// NOTE: This will only work if GenericMediaStream.CachingEnabled is true.
public IEnumerable <ulong> EnumerateSyncPoints(IVideoTrack vTrack)
{
IMediaTrackSliceEnumerator sliceEnum = (IMediaTrackSliceEnumerator)vTrack.GetEnumerator();
ulong lastTimeStamp = 0;
while (sliceEnum.MoveNext())
{
Slice slice = sliceEnum.Current;
if (slice == null)
{
break;
}
if (slice.SliceType == SliceType.IFrame)
{
var timeStamp = sliceEnum.CurrentTimeStampNew.Value; // guaranteed as this is an iframe...
//Common.Logger.Instance.Info("[GenericRecodeWRC::SyncPoints] timeStamp [" + timeStamp + "]");
yield return(timeStamp);
}
if (sliceEnum.CurrentTimeStampNew.HasValue && sliceEnum.CurrentTimeStampNew.Value > 0)
{
lastTimeStamp = sliceEnum.CurrentTimeStampNew.Value;
}
}
//Common.Logger.Instance.Info("[GenericRecodeWRC::SyncPoints] timeStamp [" + lastTimeStamp + "]");
yield return(lastTimeStamp); // last slice is NOT an IFrame, but it is a syncpoint nevertheless
}
/// <summary>
/// Look into a slice just to get width, height, and aspect ratio.
/// NOTE: This is no longer used.
/// </summary>
private void GetScreenDimensions(IVideoTrack video)
{
if ((video.PayloadType == VideoPayloadType.unknown) || (video.PayloadType == VideoPayloadType.jpeg) || (video.PayloadType == VideoPayloadType.mjpeg))
{
return;
}
// this will only work for H.264 video source
IMediaTrackSliceEnumerator slices = (IMediaTrackSliceEnumerator)video.GetEnumerator();
slices.MoveNext();
Slice slice = slices.Current;;
int countToZero = slice.SliceSize;
ulong totalSize = 0UL;
BinaryReader reader = new BinaryReader(new MemoryStream(slice.SliceBytes));
while (countToZero > 4)
{
ulong naluLen = BE32(reader.ReadUInt32());
long nextPos = reader.BaseStream.Position + (long)naluLen;
uint typ = reader.ReadByte();
if ((naluLen > (ulong)countToZero) || (naluLen < 2))
{
throw new Exception("Invalid video payload");
}
// access unit delimiter (aud) always comes first and its size is not added to total size because
// it is be added back to the payload.
if ((typ & 0x1Fu) == 9u)
{
if (naluLen != 2)
{
throw new Exception("Wrong nalu delimiter length");
}
reader.ReadByte(); // discard (we don't need it here)
}
// if nalu type is Sequence Param Set, pick up width and height
// also, build private codec data from this SPS
// NOTE: it matters which video track this qbox belongs!
if ((typ & 0x1Fu) == 7u)
{
byte[] buf = new byte[naluLen];
reader.Read(buf, 1, (int)naluLen - 1);
totalSize += (4 + naluLen);
// parse the SPS bit stream, just to get the correct width and height of video.
BitReader bitReader = new BitReader(new MemoryStream(buf));
SequenceParameterSet sps = new SequenceParameterSet((uint)naluLen);
sps.Read(bitReader);
Width = (int)sps.Width;
Height = (int)sps.Height;
if (sps.VUIParametersPresent)
{
AspectRatioX = sps.vuiParams.AspectRatioX;
AspectRatioY = sps.vuiParams.AspectRatioY;
}
}
countToZero -= ((int)naluLen + 4);
reader.BaseStream.Position = nextPos;
}
}
