RtpStream does not exclude RTP package when the payload type of RTP package mismatches with payload number in describe（SDP）

[xingshuangs]

Describe the bug
I 'm not sure if this is a bug, as this is first time I commit the issue.
In my case, I need to remote control cameras, just rotate it.
When I rotate it, the timestamp of RawFrame in feedback will be discontinuous, so I think the frame is alse not discontinuous.
When I do not rotate it, the frame will be continuous.

Why?

I find that the payload type is 105 and the sequence number adds 1 normally in every rtp package when I do not remote rotate, the payload type will be 50 and the sequence number will not be changed in rtp package as I rotate.
In the function 'ProcessImmediately' of RtpSteam class, it does not exclude the rtp package mismatches with payload number in SDP, and it invokes ‘_mediaPayloadParser.ResetState()’ immediately when the ‘SeqNumber‘ offset is not equal to 1.

 SyncSourceId = rtpPacket.SyncSourceId;
            if (!_isFirstPacket)
            {
                int delta = (ushort) (rtpPacket.SeqNumber - _previousSeqNumber);

                if (delta != 1)
                {
                    int lostCount = delta - 1;

                    if (lostCount == -1)
                        lostCount = ushort.MaxValue;

                    CumulativePacketLost += (uint) lostCount;

                    if (CumulativePacketLost > 0x7FFFFF)
                        CumulativePacketLost = 0x7FFFFF;

                    PacketsLostSinceLastReset += lostCount;

                    _mediaPayloadParser.ResetState();
                }

                if (rtpPacket.SeqNumber < HighestSequenceNumberReceived)
                    ++SequenceCycles;

                _samplesSum += rtpPacket.Timestamp - _previousTimestamp;
            }

To Change
Steps to change the behavior:

1. In 'PayloadFormatInfo' class, I add 'PayloadFormatNumber' property, and add 'PayloadFormatNumber' to 'PayloadFormatInfo' object when 'ParseMediaLine' .

private class PayloadFormatInfo
        {
            public string TrackName { get; set; }
            public CodecInfo CodecInfo { get; set; }
            public int SamplesFrequency { get; set; }
            public int PayloadFormatNumber { get; set; }

            public PayloadFormatInfo(CodecInfo codecInfo, int samplesFrequency,int payloadFormatNumber)
            {
                CodecInfo = codecInfo;
                SamplesFrequency = samplesFrequency;
                PayloadFormatNumber = payloadFormatNumber;
            }
        }

private void ParseMediaLine(string line)
        {
            string[] tokens = line.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);

            if (tokens.Length < 4)
            {
                _lastParsedFormatInfo = null;
                return;
            }

            string payloadFormat = tokens[3];

            if (!int.TryParse(payloadFormat, out int payloadFormatNumber))
            {
                _lastParsedFormatInfo = null;
                return;
            }

            CodecInfo codecInfo = TryCreateCodecInfo(payloadFormatNumber);
            int samplesFrequency = GetSamplesFrequencyFromPayloadType(payloadFormatNumber);

            _lastParsedFormatInfo = new PayloadFormatInfo(codecInfo, samplesFrequency, payloadFormatNumber);
            _payloadFormatNumberToInfoMap[payloadFormatNumber] = _lastParsedFormatInfo;
        }

2. Add ‘_payloadFormatNumber’ field in ‘RtpStream’ class

class RtpStream : ITransportStream, IRtpStatisticsProvider
    {
        private readonly IRtpSequenceAssembler _rtpSequenceAssembler;
        private readonly IMediaPayloadParser _mediaPayloadParser;
        private readonly int _samplesFrequency;
        private readonly int _payloadFormatNumber;

.... ....


public RtpStream(IMediaPayloadParser mediaPayloadParser, int samplesFrequency,
            IRtpSequenceAssembler rtpSequenceAssembler = null, int payloadFormatNumber = -1)
        {
            _mediaPayloadParser = mediaPayloadParser ?? throw new ArgumentNullException(nameof(mediaPayloadParser));
            _samplesFrequency = samplesFrequency;

            if (rtpSequenceAssembler != null)
            {
                _rtpSequenceAssembler = rtpSequenceAssembler;
                _rtpSequenceAssembler.PacketPassed += ProcessImmediately;
            }
            _payloadFormatNumber = payloadFormatNumber;
        }

add ‘track.PayloadFormatNumber’ to ‘RtpStream’ object in the function 'SetupTrackAsync' of 'RtspClientInternal' class,

 var rtpStream = new RtpStream(mediaPayloadParser, track.SamplesFrequency, rtpSequenceAssembler,track.PayloadFormatNumber);
            _streamsMap.Add(rtpChannelNumber, rtpStream);

3. Add filter code in the function 'ProcessImmediately' of 'RtpStream' class .

 private void ProcessImmediately(ref RtpPacket rtpPacket)
        {
            SyncSourceId = rtpPacket.SyncSourceId;

            if (_payloadFormatNumber > 0 && _payloadFormatNumber != rtpPacket.PayloadType) return;

            if (!_isFirstPacket)
            {
                int delta = (ushort) (rtpPacket.SeqNumber - _previousSeqNumber);

                if (delta != 1)
                {
                    int lostCount = delta - 1;

                    if (lostCount == -1)
                        lostCount = ushort.MaxValue;

                    CumulativePacketLost += (uint) lostCount;

                    if (CumulativePacketLost > 0x7FFFFF)
                        CumulativePacketLost = 0x7FFFFF;

                    PacketsLostSinceLastReset += lostCount;

                    _mediaPayloadParser.ResetState();
                }

                if (rtpPacket.SeqNumber < HighestSequenceNumberReceived)
                    ++SequenceCycles;

                _samplesSum += rtpPacket.Timestamp - _previousTimestamp;
            }

4. that‘s all.

Additional context
Looking forward to your reply.