rtp.c

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.7平台上编译为嵌入式图形界面操作系统。

/*
 * RTP input/output format
 * Copyright (c) 2002 Fabrice Bellard.
 *
 * This library 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 of the License, or (at your option) any later version.
 *
 * This library 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 this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#include "avformat.h"

#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#ifndef __BEOS__
# include <arpa/inet.h>
#else
# include "barpainet.h"
#endif
#include <netdb.h>

//#define DEBUG


/* TODO: - add RTCP statistics reporting (should be optional).

         - add support for h263/mpeg4 packetized output : IDEA: send a
         buffer to 'rtp_write_packet' contains all the packets for ONE
         frame. Each packet should have a four byte header containing
         the length in big endian format (same trick as
         'url_open_dyn_packet_buf') 
*/

#define RTP_VERSION 2

#define RTP_MAX_SDES 256   /* maximum text length for SDES */

/* RTCP paquets use 0.5 % of the bandwidth */
#define RTCP_TX_RATIO_NUM 5
#define RTCP_TX_RATIO_DEN 1000

typedef enum {
  RTCP_SR   = 200,
  RTCP_RR   = 201,
  RTCP_SDES = 202,
  RTCP_BYE  = 203,
  RTCP_APP  = 204
} rtcp_type_t;

typedef enum {
  RTCP_SDES_END    =  0,
  RTCP_SDES_CNAME  =  1,
  RTCP_SDES_NAME   =  2,
  RTCP_SDES_EMAIL  =  3,
  RTCP_SDES_PHONE  =  4,
  RTCP_SDES_LOC    =  5,
  RTCP_SDES_TOOL   =  6,
  RTCP_SDES_NOTE   =  7,
  RTCP_SDES_PRIV   =  8, 
  RTCP_SDES_IMG    =  9,
  RTCP_SDES_DOOR   = 10,
  RTCP_SDES_SOURCE = 11
} rtcp_sdes_type_t;

enum RTPPayloadType {
    RTP_PT_ULAW = 0,
    RTP_PT_GSM = 3,
    RTP_PT_G723 = 4,
    RTP_PT_ALAW = 8,
    RTP_PT_S16BE_STEREO = 10,
    RTP_PT_S16BE_MONO = 11,
    RTP_PT_MPEGAUDIO = 14,
    RTP_PT_JPEG = 26,
    RTP_PT_H261 = 31,
    RTP_PT_MPEGVIDEO = 32,
    RTP_PT_MPEG2TS = 33,
    RTP_PT_H263 = 34, /* old H263 encapsulation */
    RTP_PT_PRIVATE = 96,
};

typedef struct RTPContext {
    int payload_type;
    UINT32 ssrc;
    UINT16 seq;
    UINT32 timestamp;
    UINT32 base_timestamp;
    UINT32 cur_timestamp;
    int max_payload_size;
    /* rtcp sender statistics receive */
    INT64 last_rtcp_ntp_time;
    UINT32 last_rtcp_timestamp;
    /* rtcp sender statistics */
    unsigned int packet_count;
    unsigned int octet_count;
    unsigned int last_octet_count;
    int first_packet;
    /* buffer for output */
    UINT8 buf[RTP_MAX_PACKET_LENGTH];
    UINT8 *buf_ptr;
} RTPContext;

int rtp_get_codec_info(AVCodecContext *codec, int payload_type)
{
    switch(payload_type) {
    case RTP_PT_ULAW:
        codec->codec_id = CODEC_ID_PCM_MULAW;
        codec->channels = 1;
        codec->sample_rate = 8000;
        break;
    case RTP_PT_ALAW:
        codec->codec_id = CODEC_ID_PCM_ALAW;
        codec->channels = 1;
        codec->sample_rate = 8000;
        break;
    case RTP_PT_S16BE_STEREO:
        codec->codec_id = CODEC_ID_PCM_S16BE;
        codec->channels = 2;
        codec->sample_rate = 44100;
        break;
    case RTP_PT_S16BE_MONO:
        codec->codec_id = CODEC_ID_PCM_S16BE;
        codec->channels = 1;
        codec->sample_rate = 44100;
        break;
    case RTP_PT_MPEGAUDIO:
        codec->codec_id = CODEC_ID_MP2;
        break;
    case RTP_PT_JPEG:
        codec->codec_id = CODEC_ID_MJPEG;
        break;
    case RTP_PT_MPEGVIDEO:
        codec->codec_id = CODEC_ID_MPEG1VIDEO;
        break;
    default:
        return -1;
    }
    return 0;
}

/* return < 0 if unknown payload type */
int rtp_get_payload_type(AVCodecContext *codec)
{
    int payload_type;

    /* compute the payload type */
    payload_type = -1;
    switch(codec->codec_id) {
    case CODEC_ID_PCM_MULAW:
        payload_type = RTP_PT_ULAW;
        break;
    case CODEC_ID_PCM_ALAW:
        payload_type = RTP_PT_ALAW;
        break;
    case CODEC_ID_PCM_S16BE:
        if (codec->channels == 1) {
            payload_type = RTP_PT_S16BE_MONO;
        } else if (codec->channels == 2) {
            payload_type = RTP_PT_S16BE_STEREO;
        }
        break;
    case CODEC_ID_MP2:
    case CODEC_ID_MP3LAME:
        payload_type = RTP_PT_MPEGAUDIO;
        break;
    case CODEC_ID_MJPEG:
        payload_type = RTP_PT_JPEG;
        break;
    case CODEC_ID_MPEG1VIDEO:
        payload_type = RTP_PT_MPEGVIDEO;
        break;
    default:
        break;
    }
    return payload_type;
}

static inline UINT32 decode_be32(const UINT8 *p)
{
    return (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
}

static inline UINT32 decode_be64(const UINT8 *p)
{
    return ((UINT64)decode_be32(p) << 32) | decode_be32(p + 4);
}

static int rtcp_parse_packet(AVFormatContext *s1, const unsigned char *buf, int len)
{
    RTPContext *s = s1->priv_data;

    if (buf[1] != 200)
        return -1;
    s->last_rtcp_ntp_time = decode_be64(buf + 8);
    s->last_rtcp_timestamp = decode_be32(buf + 16);
    return 0;
}

/**
 * Parse an RTP packet directly sent as raw data. Can only be used if
 * 'raw' is given as input file
 * @param s1 media file context
 * @param pkt returned packet
 * @param buf input buffer
 * @param len buffer len
 * @return zero if no error.
 */
int rtp_parse_packet(AVFormatContext *s1, AVPacket *pkt, 
                     const unsigned char *buf, int len)
{
    RTPContext *s = s1->priv_data;
    unsigned int ssrc, h;
    int payload_type, seq, delta_timestamp;
    AVStream *st;
    UINT32 timestamp;
    
    if (len < 12)
        return -1;

    if ((buf[0] & 0xc0) != (RTP_VERSION << 6))
        return -1;
    if (buf[1] >= 200 && buf[1] <= 204) {
        rtcp_parse_packet(s1, buf, len);
        return -1;
    }
    payload_type = buf[1] & 0x7f;
    seq  = (buf[2] << 8) | buf[3];
    timestamp = decode_be32(buf + 4);
    ssrc = decode_be32(buf + 8);
    
    if (s->payload_type < 0) {
        s->payload_type = payload_type;
        
        if (payload_type == RTP_PT_MPEG2TS) {
            /* XXX: special case : not a single codec but a whole stream */
            return -1;
        } else {
            st = av_new_stream(s1, 0);
            if (!st)
                return -1;
            rtp_get_codec_info(&st->codec, payload_type);
        }
    }

    /* NOTE: we can handle only one payload type */
    if (s->payload_type != payload_type)
        return -1;
#if defined(DEBUG) || 1
    if (seq != ((s->seq + 1) & 0xffff)) {
        printf("RTP: PT=%02x: bad cseq %04x expected=%04x\n", 
               payload_type, seq, ((s->seq + 1) & 0xffff));
    }
    s->seq = seq;
#endif
    len -= 12;
    buf += 12;
    st = s1->streams[0];
    switch(st->codec.codec_id) {
    case CODEC_ID_MP2:
        /* better than nothing: skip mpeg audio RTP header */
        if (len <= 4)
            return -1;
        h = decode_be32(buf);
        len -= 4;
        buf += 4;
        av_new_packet(pkt, len);
        memcpy(pkt->data, buf, len);
        break;
    case CODEC_ID_MPEG1VIDEO:
        /* better than nothing: skip mpeg audio RTP header */
        if (len <= 4)
            return -1;
        h = decode_be32(buf);
        buf += 4;
        len -= 4;
        if (h & (1 << 26)) {
            /* mpeg2 */
            if (len <= 4)
                return -1;
            buf += 4;
            len -= 4;
        }
        av_new_packet(pkt, len);
        memcpy(pkt->data, buf, len);
        break;
    default:
        av_new_packet(pkt, len);
        memcpy(pkt->data, buf, len);
        break;
    }

    if (s->last_rtcp_ntp_time != AV_NOPTS_VALUE) {
        /* compute pts from timestamp with received ntp_time */
        delta_timestamp = timestamp - s->last_rtcp_timestamp;
        /* XXX: do conversion, but not needed for mpeg at 90 KhZ */
        pkt->pts = s->last_rtcp_ntp_time + delta_timestamp;
    }
    return 0;
}

static int rtp_read_header(AVFormatContext *s1,
                           AVFormatParameters *ap)
{
    RTPContext *s = s1->priv_data;
    s->payload_type = -1;
    s->last_rtcp_ntp_time = AV_NOPTS_VALUE;
    return 0;
}

static int rtp_read_packet(AVFormatContext *s1, AVPacket *pkt)
{
    char buf[RTP_MAX_PACKET_LENGTH];
    int ret;

    /* XXX: needs a better API for packet handling ? */
    for(;;) {
        ret = url_read(url_fileno(&s1->pb), buf, sizeof(buf));
        if (ret < 0)
            return AVERROR_IO;
        if (rtp_parse_packet(s1, pkt, buf, ret) == 0)
            break;
    }
    return 0;
}

static int rtp_read_close(AVFormatContext *s1)
{
    //    RTPContext *s = s1->priv_data;
    return 0;
}

static int rtp_probe(AVProbeData *p)
{
    if (strstart(p->filename, "rtp://", NULL))
        return AVPROBE_SCORE_MAX;