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H264VideoPayloadParser.cs
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H264VideoPayloadParser.cs
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using System;
using System.Diagnostics;
using System.IO;
using RtspClientSharp.Codecs.Video;
using RtspClientSharp.RawFrames.Video;
using RtspClientSharp.Utils;
namespace RtspClientSharp.MediaParsers
{
class H264VideoPayloadParser : MediaPayloadParser
{
enum PackModeType
{
STAP_A = 24,
STAP_B = 25,
MTAP16 = 26,
MTAP24 = 27,
FU_A = 28,
FU_B = 29
}
const int DecodingOrderNumberFieldSize = 2;
const int DondFieldSize = 1;
private readonly H264Parser _h264Parser;
private readonly MemoryStream _nalStream;
private bool _waitForStartFu = true;
private TimeSpan _timeOffset = TimeSpan.MinValue;
public H264VideoPayloadParser(H264CodecInfo codecInfo)
{
if (codecInfo == null)
throw new ArgumentNullException(nameof(codecInfo));
if (codecInfo.SpsPpsBytes == null)
throw new ArgumentException($"{nameof(codecInfo.SpsPpsBytes)} is null", nameof(codecInfo));
_h264Parser = new H264Parser(() => GetFrameTimestamp(_timeOffset)) {FrameGenerated = OnFrameGenerated};
if (codecInfo.SpsPpsBytes.Length != 0)
_h264Parser.Parse(new ArraySegment<byte>(codecInfo.SpsPpsBytes), false);
_nalStream = new MemoryStream(8 * 1024);
}
public override void Parse(TimeSpan timeOffset, ArraySegment<byte> byteSegment, bool markerBit)
{
Debug.Assert(byteSegment.Array != null, "byteSegment.Array != null");
if (!markerBit && timeOffset != _timeOffset)
_h264Parser.TryGenerateFrame();
_timeOffset = timeOffset;
PackModeType packMode = (PackModeType) (byteSegment.Array[byteSegment.Offset] & 0x1F);
switch (packMode)
{
case PackModeType.FU_A:
ParseFU(byteSegment, 0, markerBit);
break;
case PackModeType.FU_B:
ParseFU(byteSegment, DecodingOrderNumberFieldSize, markerBit);
break;
case PackModeType.STAP_A:
ParseSTAP(byteSegment, 0, markerBit);
break;
case PackModeType.STAP_B:
ParseSTAP(byteSegment, DecodingOrderNumberFieldSize, markerBit);
break;
case PackModeType.MTAP16:
ParseMTAP(byteSegment, 2, markerBit);
break;
case PackModeType.MTAP24:
ParseMTAP(byteSegment, 3, markerBit);
break;
default:
_h264Parser.Parse(byteSegment, markerBit);
break;
}
}
public override void ResetState()
{
_nalStream.Position = 0;
_h264Parser.ResetState();
_waitForStartFu = true;
}
private void ParseFU(ArraySegment<byte> byteSegment, int donFieldSize, bool markerBit)
{
Debug.Assert(byteSegment.Array != null, "byteSegment.Array != null");
int offset = byteSegment.Offset + 1;
int fuHeader = byteSegment.Array[offset];
bool startFlag = (fuHeader & 0x80) != 0;
bool endFlag = (fuHeader & 0x40) != 0;
if (startFlag)
{
int type = (fuHeader & 0x1F) | (byteSegment.Array[byteSegment.Offset] & 0xE0);
offset += donFieldSize;
byteSegment.Array[offset] = (byte) type;
var nalUnitSegment = new ArraySegment<byte>(byteSegment.Array, offset,
byteSegment.Offset + byteSegment.Count - offset);
if (!ArrayUtils.StartsWith(nalUnitSegment.Array, nalUnitSegment.Offset, nalUnitSegment.Count,
RawH264Frame.StartMarker))
_nalStream.Write(H264Parser.StartMarkerSegment.Array, H264Parser.StartMarkerSegment.Offset, H264Parser.StartMarkerSegment.Count);
_nalStream.Write(nalUnitSegment.Array, nalUnitSegment.Offset, nalUnitSegment.Count);
if (endFlag)
{
_h264Parser.Parse(nalUnitSegment, markerBit);
_waitForStartFu = true;
}
else
_waitForStartFu = false;
return;
}
if (_waitForStartFu)
return;
offset += donFieldSize + 1;
_nalStream.Write(byteSegment.Array, offset, byteSegment.Offset + byteSegment.Count - offset);
if (endFlag)
{
var nalUnitSegment = new ArraySegment<byte>(_nalStream.GetBuffer(), 0, (int)_nalStream.Position);
_nalStream.Position = 0;
_h264Parser.Parse(nalUnitSegment, markerBit);
_waitForStartFu = true;
}
}
private void ParseSTAP(ArraySegment<byte> byteSegment, int donFieldSize,
bool markerBit)
{
Debug.Assert(byteSegment.Array != null, "byteSegment.Array != null");
int startOffset = byteSegment.Offset + 1 + donFieldSize;
int endOffset = byteSegment.Offset + byteSegment.Count;
while (startOffset < endOffset)
{
int nalUnitSize = BigEndianConverter.ReadUInt16(byteSegment.Array, startOffset);
startOffset += 2;
var nalUnitSegment = new ArraySegment<byte>(byteSegment.Array, startOffset, nalUnitSize);
startOffset += nalUnitSize;
_h264Parser.Parse(nalUnitSegment, markerBit && startOffset >= endOffset);
}
}
private void ParseMTAP(ArraySegment<byte> byteSegment, int tsOffsetFieldSize,
bool markerBit)
{
Debug.Assert(byteSegment.Array != null, "byteSegment.Array != null");
int startOffset = byteSegment.Offset;
int endOffset = byteSegment.Offset + byteSegment.Count;
startOffset += 1 + DecodingOrderNumberFieldSize;
while (startOffset < endOffset)
{
int nalUnitSize = BigEndianConverter.ReadUInt16(byteSegment.Array, startOffset);
startOffset += 2 + DondFieldSize + tsOffsetFieldSize;
var nalUnitSegment = new ArraySegment<byte>(byteSegment.Array, startOffset, nalUnitSize);
startOffset += nalUnitSize;
_h264Parser.Parse(nalUnitSegment, markerBit && startOffset >= endOffset);
}
}
}
}