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amazon-kinesis-video-streams-rtp

The goal of the Real-time Transport Protocol (RTP) library is to provide RTP Serializer and Deserializer functionalities. Along with this, RTP library also provide codec packetization and depacketization functionality for G.711, VP8, Opus and H.264 codecs.

What is RTP?

Real-Time Transport Protocol (RTP), as defined in RFC 3550, is a data transport protocol used to deliver real-time data such as audio or video over IP networks. An RTP packet comprises of a header followed by the payload.

A RTP packet consist of following fields followed by an optional RTP Header extension.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |V=2|P|X|  CC   |M|     PT      |       Sequence Number         |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |                           Timestamp                           |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |           Synchronization Source (SSRC) identifier            |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |       Contributing Source (CSRC[0..15]) identifiers           |
        |                             ....                              |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

        RTP Header extension:

         0                   1                   2                   3
         0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |            Profile            |           Length              |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |                        Header Extension                       |
        |                             ....                              |

Using the library

Serializer

1. Call `Rtp_Init()` to initialize the RTP Context.
2. Initialize an RtpPacket_t with the desired values.
3. Call `Rtp_Serialize()` to serialize the RtpPacket_t passed.

Deserializer

1. Call `Rtp_Init()` to initialize the RTP Context.
2. Pass the serialized packet along with its length to `Rtp_DeSerialize()` to
   deserialize the packet.

Packetization

1. Call `<Codec>Packetization_Init()` to intitializae the particular codec context.
2. In case of H.264 Codec packetization -
    - Call `H264Packetizer_AddFrame()` to add  a frame OR
    - Call `H264Packetizer_AddNalu()` repeatedly to add NALUs of a frame.
3. For all codes other than H.264, call `<Codec>Packetizer_AddFrame()` to add a frame.
4. Call `<Codec>Packetizer_GetPacket()` repeatedly to retrieve the packets
   until `<Codec>_RESULT_NO_MORE_PACKETS` is returned.

Depacketization

1. Call `<Codec>Depacketization_Init()` to initialize the codec context.
2. Call `<Codec>Depacketizer_AddPacket()` repeatedly to add all packets received
   corresponding to one frame.
3. In case of H.264 Codec depacketization -
   - Call `H264Depacketizer_GetFrame()` to get a frame OR
   - Call `H264Depacketizer_GetNalu()` iteratively to get NALUs one by one until
     H264_RESULT_NO_MORE_NALUS is returned.
4. For all codes other than H.264, Call `<Codec>Depacketizer_GetFrame()` to get the
   complete frame once all packets are added.

License

This project is licensed under the Apache-2.0 License.