mpegtsenc.c

mediastreamer2是开源的网络传输媒体流的库

/*
 * MPEG2 transport stream (aka DVB) muxer
 * Copyright (c) 2003 Fabrice Bellard.
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */
#include "avformat.h"
#include "crc.h"
#include "mpegts.h"

/* write DVB SI sections */

/*********************************************/
/* mpegts section writer */

typedef struct MpegTSSection {
    int pid;
    int cc;
    void (*write_packet)(struct MpegTSSection *s, const uint8_t *packet);
    void *opaque;
} MpegTSSection;

/* NOTE: 4 bytes must be left at the end for the crc32 */
static void mpegts_write_section(MpegTSSection *s, uint8_t *buf, int len)
{
    unsigned int crc;
    unsigned char packet[TS_PACKET_SIZE];
    const unsigned char *buf_ptr;
    unsigned char *q;
    int first, b, len1, left;

    crc = bswap_32(av_crc(av_crc_get_table(AV_CRC_32_IEEE), -1, buf, len - 4));
    buf[len - 4] = (crc >> 24) & 0xff;
    buf[len - 3] = (crc >> 16) & 0xff;
    buf[len - 2] = (crc >> 8) & 0xff;
    buf[len - 1] = (crc) & 0xff;

    /* send each packet */
    buf_ptr = buf;
    while (len > 0) {
        first = (buf == buf_ptr);
        q = packet;
        *q++ = 0x47;
        b = (s->pid >> 8);
        if (first)
            b |= 0x40;
        *q++ = b;
        *q++ = s->pid;
        s->cc = (s->cc + 1) & 0xf;
        *q++ = 0x10 | s->cc;
        if (first)
            *q++ = 0; /* 0 offset */
        len1 = TS_PACKET_SIZE - (q - packet);
        if (len1 > len)
            len1 = len;
        memcpy(q, buf_ptr, len1);
        q += len1;
        /* add known padding data */
        left = TS_PACKET_SIZE - (q - packet);
        if (left > 0)
            memset(q, 0xff, left);

        s->write_packet(s, packet);

        buf_ptr += len1;
        len -= len1;
    }
}

static inline void put16(uint8_t **q_ptr, int val)
{
    uint8_t *q;
    q = *q_ptr;
    *q++ = val >> 8;
    *q++ = val;
    *q_ptr = q;
}

static int mpegts_write_section1(MpegTSSection *s, int tid, int id,
                          int version, int sec_num, int last_sec_num,
                          uint8_t *buf, int len)
{
    uint8_t section[1024], *q;
    unsigned int tot_len;

    tot_len = 3 + 5 + len + 4;
    /* check if not too big */
    if (tot_len > 1024)
        return -1;

    q = section;
    *q++ = tid;
    put16(&q, 0xb000 | (len + 5 + 4)); /* 5 byte header + 4 byte CRC */
    put16(&q, id);
    *q++ = 0xc1 | (version << 1); /* current_next_indicator = 1 */
    *q++ = sec_num;
    *q++ = last_sec_num;
    memcpy(q, buf, len);

    mpegts_write_section(s, section, tot_len);
    return 0;
}

/*********************************************/
/* mpegts writer */

#define DEFAULT_PMT_START_PID   0x1000
#define DEFAULT_START_PID       0x0100
#define DEFAULT_PROVIDER_NAME   "FFmpeg"
#define DEFAULT_SERVICE_NAME    "Service01"

/* default network id, transport stream and service identifiers */
#define DEFAULT_ONID            0x0001
#define DEFAULT_TSID            0x0001
#define DEFAULT_SID             0x0001

/* a PES packet header is generated every DEFAULT_PES_HEADER_FREQ packets */
#define DEFAULT_PES_HEADER_FREQ 16
#define DEFAULT_PES_PAYLOAD_SIZE ((DEFAULT_PES_HEADER_FREQ - 1) * 184 + 170)

/* we retransmit the SI info at this rate */
#define SDT_RETRANS_TIME 500
#define PAT_RETRANS_TIME 100
#define PCR_RETRANS_TIME 20

typedef struct MpegTSWriteStream {
    struct MpegTSService *service;
    int pid; /* stream associated pid */
    int cc;
    int payload_index;
    int64_t payload_pts;
    int64_t payload_dts;
    uint8_t payload[DEFAULT_PES_PAYLOAD_SIZE];
} MpegTSWriteStream;

typedef struct MpegTSService {
    MpegTSSection pmt; /* MPEG2 pmt table context */
    int sid;           /* service ID */
    char *name;
    char *provider_name;
    int pcr_pid;
    int pcr_packet_count;
    int pcr_packet_freq;
} MpegTSService;

typedef struct MpegTSWrite {
    MpegTSSection pat; /* MPEG2 pat table */
    MpegTSSection sdt; /* MPEG2 sdt table context */
    MpegTSService **services;
    int sdt_packet_count;
    int sdt_packet_freq;
    int pat_packet_count;
    int pat_packet_freq;
    int nb_services;
    int onid;
    int tsid;
} MpegTSWrite;

static void mpegts_write_pat(AVFormatContext *s)
{
    MpegTSWrite *ts = s->priv_data;
    MpegTSService *service;
    uint8_t data[1012], *q;
    int i;

    q = data;
    for(i = 0; i < ts->nb_services; i++) {
        service = ts->services[i];
        put16(&q, service->sid);
        put16(&q, 0xe000 | service->pmt.pid);
    }
    mpegts_write_section1(&ts->pat, PAT_TID, ts->tsid, 0, 0, 0,
                          data, q - data);
}

static void mpegts_write_pmt(AVFormatContext *s, MpegTSService *service)
{
    //    MpegTSWrite *ts = s->priv_data;
    uint8_t data[1012], *q, *desc_length_ptr, *program_info_length_ptr;
    int val, stream_type, i;

    q = data;
    put16(&q, 0xe000 | service->pcr_pid);

    program_info_length_ptr = q;
    q += 2; /* patched after */

    /* put program info here */

    val = 0xf000 | (q - program_info_length_ptr - 2);
    program_info_length_ptr[0] = val >> 8;
    program_info_length_ptr[1] = val;

    for(i = 0; i < s->nb_streams; i++) {
        AVStream *st = s->streams[i];
        MpegTSWriteStream *ts_st = st->priv_data;
        switch(st->codec->codec_id) {
        case CODEC_ID_MPEG1VIDEO:
        case CODEC_ID_MPEG2VIDEO:
            stream_type = STREAM_TYPE_VIDEO_MPEG2;
            break;
        case CODEC_ID_MPEG4:
            stream_type = STREAM_TYPE_VIDEO_MPEG4;
            break;
        case CODEC_ID_H264:
            stream_type = STREAM_TYPE_VIDEO_H264;
            break;
        case CODEC_ID_MP2:
        case CODEC_ID_MP3:
            stream_type = STREAM_TYPE_AUDIO_MPEG1;
            break;
        case CODEC_ID_AAC:
            stream_type = STREAM_TYPE_AUDIO_AAC;
            break;
        case CODEC_ID_AC3:
            stream_type = STREAM_TYPE_AUDIO_AC3;
            break;
        default:
            stream_type = STREAM_TYPE_PRIVATE_DATA;
            break;
        }
        *q++ = stream_type;
        put16(&q, 0xe000 | ts_st->pid);
        desc_length_ptr = q;
        q += 2; /* patched after */

        /* write optional descriptors here */
        switch(st->codec->codec_type) {
        case CODEC_TYPE_AUDIO:
            if (strlen(st->language) == 3) {
                *q++ = 0x0a; /* ISO 639 language descriptor */
                *q++ = 4;
                *q++ = st->language[0];
                *q++ = st->language[1];
                *q++ = st->language[2];
                *q++ = 0; /* undefined type */
            }
            break;
        case CODEC_TYPE_SUBTITLE:
            {
                const char *language;
                language = st->language;
                if (strlen(language) != 3)
                    language = "eng";
                *q++ = 0x59;
                *q++ = 8;
                *q++ = language[0];
                *q++ = language[1];
                *q++ = language[2];
                *q++ = 0x10; /* normal subtitles (0x20 = if hearing pb) */
                put16(&q, 1); /* page id */
                put16(&q, 1); /* ancillary page id */
            }
            break;
        }

        val = 0xf000 | (q - desc_length_ptr - 2);
        desc_length_ptr[0] = val >> 8;
        desc_length_ptr[1] = val;
    }
    mpegts_write_section1(&service->pmt, PMT_TID, service->sid, 0, 0, 0,
                          data, q - data);
}

/* NOTE: str == NULL is accepted for an empty string */
static void putstr8(uint8_t **q_ptr, const char *str)
{
    uint8_t *q;
    int len;

    q = *q_ptr;
    if (!str)
        len = 0;
    else
        len = strlen(str);
    *q++ = len;
    memcpy(q, str, len);
    q += len;
    *q_ptr = q;
}

static void mpegts_write_sdt(AVFormatContext *s)
{
    MpegTSWrite *ts = s->priv_data;
    MpegTSService *service;
    uint8_t data[1012], *q, *desc_list_len_ptr, *desc_len_ptr;
    int i, running_status, free_ca_mode, val;

    q = data;
    put16(&q, ts->onid);
    *q++ = 0xff;
    for(i = 0; i < ts->nb_services; i++) {
        service = ts->services[i];
        put16(&q, service->sid);
        *q++ = 0xfc | 0x00; /* currently no EIT info */
        desc_list_len_ptr = q;
        q += 2;
        running_status = 4; /* running */
        free_ca_mode = 0;

        /* write only one descriptor for the service name and provider */
        *q++ = 0x48;
        desc_len_ptr = q;
        q++;
        *q++ = 0x01; /* digital television service */
        putstr8(&q, service->provider_name);
        putstr8(&q, service->name);
        desc_len_ptr[0] = q - desc_len_ptr - 1;

        /* fill descriptor length */
        val = (running_status << 13) | (free_ca_mode << 12) |
            (q - desc_list_len_ptr - 2);
        desc_list_len_ptr[0] = val >> 8;
        desc_list_len_ptr[1] = val;
    }
    mpegts_write_section1(&ts->sdt, SDT_TID, ts->tsid, 0, 0, 0,
                          data, q - data);
}

static MpegTSService *mpegts_add_service(MpegTSWrite *ts,
                                         int sid,
                                         const char *provider_name,
                                         const char *name)
{
    MpegTSService *service;

    service = av_mallocz(sizeof(MpegTSService));
    if (!service)
        return NULL;
    service->pmt.pid = DEFAULT_PMT_START_PID + ts->nb_services - 1;
    service->sid = sid;
    service->provider_name = av_strdup(provider_name);
    service->name = av_strdup(name);
    service->pcr_pid = 0x1fff;