// RTP Payload Format for VP9 Video draft-ietf-payload-vp9-03

#include "rtp-packet.h"
#include "rtp-profile.h"
#include "rtp-payload-internal.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <errno.h>

// Timestamp: The RTP timestamp indicates the time when the input frame was sampled, at a clock rate of 90 kHz
#define KHz 90 // 90000Hz

#define N_VP9_HEADER 1

struct rtp_encode_vp9_t {
    struct rtp_packet_t pkt;
    struct rtp_payload_t handler;
    void *cbparam;
    int size;
};

static void *rtp_vp9_pack_create(int size, uint8_t pt, uint16_t seq, uint32_t ssrc, struct rtp_payload_t *handler,
                                 void *cbparam)
{
    struct rtp_encode_vp9_t *packer;
    packer = (struct rtp_encode_vp9_t *)calloc(1, sizeof(*packer));
    if (!packer)
        return NULL;

    memcpy(&packer->handler, handler, sizeof(packer->handler));
    packer->cbparam = cbparam;
    packer->size = size;

    packer->pkt.rtp.v = RTP_VERSION;
    packer->pkt.rtp.pt = pt;
    packer->pkt.rtp.seq = seq;
    packer->pkt.rtp.ssrc = ssrc;
    return packer;
}

static void rtp_vp9_pack_destroy(void *pack)
{
    struct rtp_encode_vp9_t *packer;
    packer = (struct rtp_encode_vp9_t *)pack;
#if defined(_DEBUG) || defined(DEBUG)
    memset(packer, 0xCC, sizeof(*packer));
#endif
    free(packer);
}

static void rtp_vp9_pack_get_info(void *pack, uint16_t *seq, uint32_t *timestamp)
{
    struct rtp_encode_vp9_t *packer;
    packer = (struct rtp_encode_vp9_t *)pack;
    *seq = (uint16_t)packer->pkt.rtp.seq;
    *timestamp = packer->pkt.rtp.timestamp;
}

static int rtp_vp9_pack_input(void *pack, const void *data, int bytes, uint32_t timestamp)
{
    int r, n;
    uint8_t *rtp;
    uint8_t vp9_payload_descriptor[1];
    const uint8_t *ptr;
    struct rtp_encode_vp9_t *packer;
    packer = (struct rtp_encode_vp9_t *)pack;
    packer->pkt.rtp.timestamp = timestamp;

    r = 0;
    ptr = (const uint8_t *)data;
    // In non-flexible mode (with the F bit below set to 0),
    for (vp9_payload_descriptor[0] = 0x08 /*Start of a layer frame*/; 0 == r && bytes > 0; ++packer->pkt.rtp.seq) {
        packer->pkt.payload = ptr;
        packer->pkt.payloadlen = (bytes + N_VP9_HEADER + RTP_FIXED_HEADER) < packer->size
                                     ? bytes
                                     : (packer->size - N_VP9_HEADER - RTP_FIXED_HEADER);
        ptr += packer->pkt.payloadlen;
        bytes -= packer->pkt.payloadlen;

        n = RTP_FIXED_HEADER + N_VP9_HEADER + packer->pkt.payloadlen;
        rtp = (uint8_t *)packer->handler.alloc(packer->cbparam, n);
        if (!rtp)
            return -ENOMEM;

        // Marker bit (M): MUST be set to 1 for the final packet of the highest
        // spatial layer frame (the final packet of the super frame), and 0
        // otherwise. Unless spatial scalability is in use for this super
        // frame, this will have the same value as the E bit described below.
        // Note this bit MUST be set to 1 for the target spatial layer frame
        // if a stream is being rewritten to remove higher spatial layers.
        packer->pkt.rtp.m = (0 == bytes) ? 1 : 0;
        vp9_payload_descriptor[0] |= (0 == bytes) ? 0x04 : 0; // End of a layer frame.
        n = rtp_packet_serialize_header(&packer->pkt, rtp, n);
        if (n != RTP_FIXED_HEADER) {
            assert(0);
            return -1;
        }

        memcpy(rtp + n, vp9_payload_descriptor, N_VP9_HEADER);
        memcpy(rtp + n + N_VP9_HEADER, packer->pkt.payload, packer->pkt.payloadlen);
        r = packer->handler.packet(packer->cbparam, rtp, n + N_VP9_HEADER + packer->pkt.payloadlen,
                                   packer->pkt.rtp.timestamp, 0);
        packer->handler.free(packer->cbparam, rtp);
        vp9_payload_descriptor[0] &= ~0x08;
    }

    return r;
}

struct rtp_payload_encode_t *rtp_vp9_encode()
{
    static struct rtp_payload_encode_t encode = {
        rtp_vp9_pack_create,
        rtp_vp9_pack_destroy,
        rtp_vp9_pack_get_info,
        rtp_vp9_pack_input,
    };

    return &encode;
}