When receiving a RTP stream, will pion correct misordered packets?

[birla]

I'm trying to use this library for building a RTP Server to recieve multiple RTP streams. I want to ensure that out of order packets are reordered before they are consumed, does pion handle this internally or could anyone point me to a sample?

Much appreciated, thanks

[alexpokotilo]

@birla
what do you find during your tests ? As far as I see ReadRTP will give you packets in order they received and hence sorting reorderings(if you really need this) is your responsibility. If I am wrong, would be cool to be corrected

[Sean-Der]

Hi @birla

@alexpokotilo is correct :) By default Pion doesn't delay or de-jitter packets.

Pion does provide the SampleBuilder. You can run your RTP packets through it and it will re-order them + delay a configured amount of time for late packets.

[alexpokotilo]

Hi Sean,
thanks for confirmation! I see SampleBuilder works for re-sent packages after NACK too, right ?
I wish I have this answer in August as I made my own pure implementation. I will switch to SampleBuilder in anyway

[birla]

Thanks Alex and Sean!

[alexpokotilo]

Hi @birla

@alexpokotilo is correct :) By default Pion doesn't delay or de-jitter packets.

Pion does provide the SampleBuilder. You can run your RTP packets through it and it will re-order them + delay a configured amount of time for late packets.

I was able to use SampleBuilder to support re-order and packet loss for audio and all supported video codecs.
Thank you @Sean-Der

[half2me]

Is there a way to use the sample builder together with oggwriter?

Atm I'm just initializing the oggwriter and passing the RTP packets into it like this:
This gives me a good recording in ideal circumstances, but I'm worried about cases where RTP packets could be out of order.

writer, _ := oggwriter.New("recording.ogg", 48000, 2)

buf := make([]byte, 1600)
for {
  n, _, _ := conn.ReadFrom(buf)
  rtpPacket := &rtp.Packet{}
  _ = rtpPacket.Unmarshal(buf[:n])
  _ = m.writer.WriteRTP(rtpPacket)
}

writer.Close()

If I use the samplebuilder:

builder := samplebuilder.New(10, &codecs.OpusPacket{}, 48000) // how do I set the num of channels?

buf := make([]byte, 1600)
for {
  n, _, _ := conn.ReadFrom(buf)
  rtpPacket := &rtp.Packet{}
  _ = rtpPacket.Unmarshal(buf[:n])
  builder.Push(rtpPacket)

  sample := builder.Pop()
  if sample != nil {
    // how to I write this sample to a file?
  }
}

// how do I flush the last remaining packets out?

[shushenghong]

@half2me i have the same question, after search the code
inside the samplebuilder / oggwriter

webrtc/pkg/media/samplebuilder/samplebuilder.go

Line 285 in 1c4bc79

p, err := s.depacketizer.Unmarshal(s.buffer[i].Payload)

webrtc/pkg/media/oggwriter/oggwriter.go

Line 194 in 1c4bc79

if _, err := opusPacket.Unmarshal(packet.Payload); err != nil {

they also use opusPacket.Unmarshal, they almost the same, we need write a method to mockcreatePage with the unmarshaled data