doubao_chat/lib/net/libmpeg/source/mpeg-pmt.c

// ITU-T H.222.0(10/2014)
// Information technology – Generic coding of moving pictures and associated audio information: Systems
// 2.4.4.8 Program map table(p68)

#include "mpeg-ts-proto.h"
#include "mpeg-util.h"
#include <string.h>
#include <assert.h>

static struct pes_t *pmt_fetch(struct pmt_t *pmt, uint16_t pid)
{
    unsigned int i;
    for (i = 0; i < pmt->stream_count; i++) {
        if (pmt->streams[i].pid == pid) {
            return &pmt->streams[i];
        }
    }

    if (pmt->stream_count >= sizeof(pmt->streams) / sizeof(pmt->streams[0])) {
        assert(0);
        return NULL;
    }

    // new stream
    return &pmt->streams[pmt->stream_count++];
}

size_t pmt_read(struct pmt_t *pmt, const uint8_t *data, size_t bytes)
{
    struct pes_t *stream;
    uint16_t pid, len;
    uint32_t i = 0, k = 0;

    uint32_t table_id = data[0];
    uint32_t section_syntax_indicator = (data[1] >> 7) & 0x01;
//	uint32_t zero = (data[1] >> 6) & 0x01;
//	uint32_t reserved = (data[1] >> 4) & 0x03;
    uint32_t section_length = ((data[1] & 0x0F) << 8) | data[2];
    uint32_t program_number = (data[3] << 8) | data[4];
//	uint32_t reserved2 = (data[5] >> 6) & 0x03;
    uint32_t version_number = (data[5] >> 1) & 0x1F;
//	uint32_t current_next_indicator = data[5] & 0x01;
    uint32_t sector_number = data[6];
    uint32_t last_sector_number = data[7];
//	uint32_t reserved3 = (data[8] >> 5) & 0x07;
    uint32_t PCR_PID = ((data[8] & 0x1F) << 8) | data[9];
//	uint32_t reserved4 = (data[10] >> 4) & 0x0F;
    uint32_t program_info_length = ((data[10] & 0x0F) << 8) | data[11];

//	printf("PMT: %0x %0x %0x %0x %0x %0x %0x %0x, %0x, %0x, %0x, %0x\n", (unsigned int)data[0], (unsigned int)data[1], (unsigned int)data[2], (unsigned int)data[3], (unsigned int)data[4], (unsigned int)data[5], (unsigned int)data[6],(unsigned int)data[7],(unsigned int)data[8],(unsigned int)data[9],(unsigned int)data[10],(unsigned int)data[11]);

    assert(PAT_TID_PMS == table_id);
    assert(1 == section_syntax_indicator);
    assert(0 == sector_number);
    assert(0 == last_sector_number);
    if (pmt->ver != version_number) {
        pmt->stream_count = 0;    // clear all streams
    }

    pmt->PCR_PID = PCR_PID;
    pmt->pn = program_number;
    pmt->ver = version_number;
    pmt->pminfo_len = program_info_length;

    if (program_info_length) {
        // descriptor()
    }

    assert(bytes >= section_length + 3); // PMT = section_length + 3
    for (i = 12 + program_info_length; i + 5 <= section_length + 3 - 4/*CRC32*/; i += len + 5) { // 9: follow section_length item
        pid = ((data[i + 1] & 0x1F) << 8) | data[i + 2];
        len = ((data[i + 3] & 0x0F) << 8) | data[i + 4];
//        printf("PMT: pn: %0x, pid: %0x, codec: %0x, eslen: %d\n", (unsigned int)pmt->pn, (unsigned int)pid, (unsigned int)data[i], (unsigned int)len);

        if (i + len + 5 > section_length + 3 - 4/*CRC32*/) {
            break;
        }
        assert(pmt->stream_count <= sizeof(pmt->streams) / sizeof(pmt->streams[0]));
        stream = pmt_fetch(pmt, pid);
        if (NULL == stream) {
            continue;
        }

        stream->pn = pmt->pn;
        stream->pid = pid;
        stream->codecid = data[i];
        stream->esinfo_len = len;
        for (k = 0; k < stream->esinfo_len; k++) {
            // descriptor
        }
    }

    //assert(j+4 == bytes);
    //crc = (data[j] << 24) | (data[j+1] << 16) | (data[j+2] << 8) | data[j+3];
    assert(0 == mpeg_crc32(0xffffffff, data, section_length + 3));
    return 0;
}

size_t pmt_write(const struct pmt_t *pmt, uint8_t *data)
{
    // 2.4.4.8 Program map table (p68)
    // Table 2-33

    uint32_t i = 0;
    uint32_t crc = 0;
    ptrdiff_t len = 0;
    uint8_t *p = NULL;

    data[0] = PAT_TID_PMS;	// program map table

    // skip section_length

    // program_number
    nbo_w16(data + 3, (uint16_t)pmt->pn);

    // reserved '11'
    // version_number 'xxxxx'
    // current_next_indicator '1'
    data[5] = (uint8_t)(0xC1 | (pmt->ver << 1));

    // section_number/last_section_number
    data[6] = 0x00;
    data[7] = 0x00;

    // reserved '111'
    // PCR_PID 13-bits 0x1FFF
    nbo_w16(data + 8, (uint16_t)(0xE000 | pmt->PCR_PID));

    // reserved '1111'
    // program_info_length 12-bits, the first two bits of which shall be '00'.
    assert(pmt->pminfo_len < 0x400);
    nbo_w16(data + 10, (uint16_t)(0xF000 | pmt->pminfo_len));
    if (pmt->pminfo_len > 0 && pmt->pminfo_len < 0x400) {
        // fill program info
        assert(pmt->pminfo);
        memcpy(data + 12, pmt->pminfo, pmt->pminfo_len);
    }

    // streams
    p = data + 12 + pmt->pminfo_len;
    for (i = 0; i < pmt->stream_count && p - data < 1021 - 4 - 5 - pmt->streams[i].esinfo_len; i++) {
        // stream_type
        *p = (uint8_t)pmt->streams[i].codecid;

        // reserved '111'
        // elementary_PID 13-bits
        nbo_w16(p + 1, 0xE000 | pmt->streams[i].pid);

        // reserved '1111'
        // ES_info_lengt 12-bits
        nbo_w16(p + 3, 0xF000 | pmt->streams[i].esinfo_len);

        // fill elementary stream info
        if (pmt->streams[i].esinfo_len > 0) {
            assert(pmt->streams[i].esinfo);
            memcpy(p + 5, pmt->streams[i].esinfo, pmt->streams[i].esinfo_len);
        }

        p += 5 + pmt->streams[i].esinfo_len;
    }

    // section_length
    len = p + 4 - (data + 3); // 4 bytes crc32
    assert(len <= 1021); // shall not exceed 1021 (0x3FD).
    assert(len <= TS_PACKET_SIZE - 7);
    // section_syntax_indicator '1'
    // '0'
    // reserved '11'
    nbo_w16(data + 1, (uint16_t)(0xb000 | len));

    // crc32
    crc = mpeg_crc32(0xffffffff, data, (uint32_t)(p - data));
    //put32(p, crc);
    p[3] = (crc >> 24) & 0xFF;
    p[2] = (crc >> 16) & 0xFF;
    p[1] = (crc >> 8) & 0xFF;
    p[0] = crc & 0xFF;

    return (p - data) + 4; // total length
}