doubao_chat/lib/net/libmpeg/source/mpeg-ps-dec.c

// ITU-T H.222.0(06/2012)
// Information technology – Generic coding of moving pictures and associated audio information: Systems
// 2.5.3.1 Program stream(p74)

#include <stdlib.h>
#include "mpeg-ps.h"
#include "mpeg-ps-proto.h"
#include "mpeg-ts-proto.h"
#include "mpeg-pes-proto.h"
#include <assert.h>
#include <string.h>

struct ps_demuxer_t {
    struct psm_t psm;
    struct psd_t psd;

    struct ps_pack_header_t pkhd;
    struct ps_system_header_t system;

    ps_demuxer_onpacket onpacket;
    void *param;
};

static int ps_demuxer_onpes(void *param, int program, int stream, int codecid, int flags, int64_t pts, int64_t dts, const void *data, size_t bytes)
{
    struct ps_demuxer_t *ps;
    ps = (struct ps_demuxer_t *)param;
    assert(0 == program); // unused(ts demux only)
    ps->onpacket(ps->param, stream, codecid, flags, pts, dts, data, bytes);
    return 0;
}

static struct pes_t *psm_fetch(struct psm_t *psm, uint8_t sid)
{
    size_t i;
    for (i = 0; i < psm->stream_count; ++i) {
        if (psm->streams[i].sid == sid) {
            return &psm->streams[i];
        }
    }

    if (psm->stream_count < sizeof(psm->streams) / sizeof(psm->streams[0])) {
        // '110x xxxx'
        // ISO/IEC 13818-3 or ISO/IEC 11172-3 or ISO/IEC 13818-7 or
        // ISO/IEC 14496-3 or ISO/IEC 23008-3 audio stream number 'x xxxx'

        // '1110 xxxx'
        // Rec. ITU-T H.262 | ISO/IEC 13818-2, ISO/IEC 11172-2, ISO/IEC 14496-2,
        // Rec. ITU-T H.264 | ISO/IEC 14496-10 or
        // Rec. ITU-T H.265 | ISO/IEC 23008-2 video stream number 'xxxx'

        // guess stream codec id
        if (0xE0 <= sid && sid <= 0xEF) {
            psm->streams[psm->stream_count].codecid = PSI_STREAM_H264;
        } else if (0xC0 <= sid && sid <= 0xDF) {
            psm->streams[psm->stream_count].codecid = PSI_STREAM_AAC;
        }

        return &psm->streams[psm->stream_count++];
    }

    return NULL;
}

static size_t pes_packet_read(struct ps_demuxer_t *ps, const uint8_t *data, size_t bytes)
{
    size_t i = 0;
    size_t j = 0;
    size_t pes_packet_length;
    struct pes_t *pes;

    // MPEG_program_end_code = 0x000001B9
    for (i = 0; i + 5 < bytes && 0x00 == data[i] && 0x00 == data[i + 1] && 0x01 == data[i + 2]
         && PES_SID_END != data[i + 3]
         && PES_SID_START != data[i + 3];
         i += pes_packet_length + 6) {
        pes_packet_length = (data[i + 4] << 8) | data[i + 5];
        //assert(i + 6 + pes_packet_length <= bytes);
        if (i + 6 + pes_packet_length > bytes) {
            return i;
        }

        // stream id
        switch (data[i + 3]) {
        case PES_SID_PSM:
            j = psm_read(&ps->psm, data + i, bytes - i);
            assert(j == pes_packet_length + 6);
            break;

        case PES_SID_PSD:
            j = psd_read(&ps->psd, data + i, bytes - i);
            assert(j == pes_packet_length + 6);
            break;

        case PES_SID_PRIVATE_2:
        case PES_SID_ECM:
        case PES_SID_EMM:
        case PES_SID_DSMCC:
        case PES_SID_H222_E:
            // stream data
            break;

        case PES_SID_PADDING:
            // padding
            break;

        // ffmpeg mpeg.c mpegps_read_pes_header
        //case 0x1c0:
        //case 0x1df:
        //case 0x1e0:
        //case 0x1ef:
        //case 0x1bd:
        //case 0x01fd:
        //	break;

        default:
            pes = psm_fetch(&ps->psm, data[i + 3]);
            if (NULL == pes) {
                continue;
            }

            assert(PES_SID_END != data[i + 3]);
            if (ps->pkhd.mpeg2) {
                j = pes_read_header(pes, data + i, bytes - i);
            } else {
                j = pes_read_mpeg1_header(pes, data + i, bytes - i);
            }

            if (0 == j) {
                continue;
            }

            pes_packet(&pes->pkt, pes, data + i + j, pes_packet_length + 6 - j, ps_demuxer_onpes, ps);
        }
    }

    return i;
}

size_t ps_demuxer_input(struct ps_demuxer_t *ps, const uint8_t *data, size_t bytes)
{
    size_t i, n;
    const uint8_t *p, *pend;

    // location ps start
    p = data;
    pend = data + bytes;
    while (p && pend - p > 3) {
        p = memchr(p + 3, PES_SID_START, pend - p - 3);
        if (p && 0x01 == *(p - 1) && 0x00 == *(p - 2) && 0x00 == *(p - 3)) {
            break;
        }
    }

    for (i = (p && p >= data + 3) ? p - data - 3 : 0; i + 3 < bytes && data && 0x00 == data[i] && 0x00 == data[i + 1] && 0x01 == data[i + 2];) {
        if (PES_SID_START == data[i + 3]) {
            i += pack_header_read(&ps->pkhd, data + i, bytes - i);
        } else if (PES_SID_SYS == data[i + 3]) {
            i += system_header_read(&ps->system, data + i, bytes - i);
        } else if (PES_SID_END == data[i + 3]) {
            i += 4;
        } else {
            n = pes_packet_read(ps, data + i, bytes - i);
            i += n;

            if (0 == n) {
                break;
            }
        }
    }

    return i;
}

struct ps_demuxer_t *ps_demuxer_create(ps_demuxer_onpacket onpacket, void *param)
{
    struct ps_demuxer_t *ps;
    ps = calloc(1, sizeof(struct ps_demuxer_t));
    if (!ps) {
        return NULL;
    }

    ps->pkhd.mpeg2 = 1;
    ps->onpacket = onpacket;
    ps->param = param;
    return ps;
}

int ps_demuxer_destroy(struct ps_demuxer_t *ps)
{
    size_t i;
    struct pes_t *pes;
    for (i = 0; i < ps->psm.stream_count; i++) {
        pes = &ps->psm.streams[i];
        if (pes->pkt.data) {
            free(pes->pkt.data);
        }
        pes->pkt.data = NULL;
    }

    free(ps);
    return 0;
}