FFmpeg4/libavformat/rtspenc.c

/*
 * RTSP muxer
 * Copyright (c) 2010 Martin Storsjo
 *
 * 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"

#if HAVE_POLL_H
#include <poll.h>
#endif
#include "network.h"
#include "os_support.h"
#include "rtsp.h"
#include "internal.h"
#include "avio_internal.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/avstring.h"
#include "libavutil/time.h"
#include "url.h"

#define SDP_MAX_SIZE 16384

static const AVClass rtsp_muxer_class = {
    .class_name = "RTSP muxer",
    .item_name  = av_default_item_name,
    .option     = ff_rtsp_options,
    .version    = LIBAVUTIL_VERSION_INT,
};

int ff_rtsp_setup_output_streams(AVFormatContext *s, const char *addr)
{
    RTSPState *rt = s->priv_data;
    RTSPMessageHeader reply1, *reply = &reply1;
    int i;
    char *sdp;
    AVFormatContext sdp_ctx, *ctx_array[1];
    char url[1024];

    if (s->start_time_realtime == 0  ||  s->start_time_realtime == AV_NOPTS_VALUE)
        s->start_time_realtime = av_gettime();

    /* Announce the stream */
    sdp = av_mallocz(SDP_MAX_SIZE);
    if (!sdp)
        return AVERROR(ENOMEM);
    /* We create the SDP based on the RTSP AVFormatContext where we
     * aren't allowed to change the filename field. (We create the SDP
     * based on the RTSP context since the contexts for the RTP streams
     * don't exist yet.) In order to specify a custom URL with the actual
     * peer IP instead of the originally specified hostname, we create
     * a temporary copy of the AVFormatContext, where the custom URL is set.
     *
     * FIXME: Create the SDP without copying the AVFormatContext.
     * This either requires setting up the RTP stream AVFormatContexts
     * already here (complicating things immensely) or getting a more
     * flexible SDP creation interface.
     */
    sdp_ctx = *s;
    sdp_ctx.url = url;
    ff_url_join(url, sizeof(url),
                "rtsp", NULL, addr, -1, NULL);
    ctx_array[0] = &sdp_ctx;
    if (av_sdp_create(ctx_array, 1, sdp, SDP_MAX_SIZE)) {
        av_free(sdp);
        return AVERROR_INVALIDDATA;
    }
    av_log(s, AV_LOG_VERBOSE, "SDP:\n%s\n", sdp);
    ff_rtsp_send_cmd_with_content(s, "ANNOUNCE", rt->control_uri,
                                  "Content-Type: application/sdp\r\n",
                                  reply, NULL, sdp, strlen(sdp));
    av_free(sdp);
    if (reply->status_code != RTSP_STATUS_OK)
        return ff_rtsp_averror(reply->status_code, AVERROR_INVALIDDATA);

    /* Set up the RTSPStreams for each AVStream */
    for (i = 0; i < s->nb_streams; i++) {
        RTSPStream *rtsp_st;

        rtsp_st = av_mallocz(sizeof(RTSPStream));
        if (!rtsp_st)
            return AVERROR(ENOMEM);
        dynarray_add(&rt->rtsp_streams, &rt->nb_rtsp_streams, rtsp_st);

        rtsp_st->stream_index = i;

        av_strlcpy(rtsp_st->control_url, rt->control_uri, sizeof(rtsp_st->control_url));
        /* Note, this must match the relative uri set in the sdp content */
        av_strlcatf(rtsp_st->control_url, sizeof(rtsp_st->control_url),
                    "/streamid=%d", i);
    }

    return 0;
}

static int rtsp_write_record(AVFormatContext *s)
{
    RTSPState *rt = s->priv_data;
    RTSPMessageHeader reply1, *reply = &reply1;
    char cmd[1024];

    snprintf(cmd, sizeof(cmd),
             "Range: npt=0.000-\r\n");
    ff_rtsp_send_cmd(s, "RECORD", rt->control_uri, cmd, reply, NULL);
    if (reply->status_code != RTSP_STATUS_OK)
        return ff_rtsp_averror(reply->status_code, -1);
    rt->state = RTSP_STATE_STREAMING;
    return 0;
}

static int rtsp_write_header(AVFormatContext *s)
{
    int ret;

    ret = ff_rtsp_connect(s);
    if (ret)
        return ret;

    if (rtsp_write_record(s) < 0) {
        ff_rtsp_close_streams(s);
        ff_rtsp_close_connections(s);
        return AVERROR_INVALIDDATA;
    }
    return 0;
}

int ff_rtsp_tcp_write_packet(AVFormatContext *s, RTSPStream *rtsp_st)
{
    RTSPState *rt = s->priv_data;
    AVFormatContext *rtpctx = rtsp_st->transport_priv;
    uint8_t *buf, *ptr;
    int size;
    uint8_t *interleave_header, *interleaved_packet;

    size = avio_close_dyn_buf(rtpctx->pb, &buf);
    rtpctx->pb = NULL;
    ptr = buf;
    while (size > 4) {
        uint32_t packet_len = AV_RB32(ptr);
        int id;
        /* The interleaving header is exactly 4 bytes, which happens to be
         * the same size as the packet length header from
         * ffio_open_dyn_packet_buf. So by writing the interleaving header
         * over these bytes, we get a consecutive interleaved packet
         * that can be written in one call. */
        interleaved_packet = interleave_header = ptr;
        ptr += 4;
        size -= 4;
        if (packet_len > size || packet_len < 2)
            break;
        if (RTP_PT_IS_RTCP(ptr[1]))
            id = rtsp_st->interleaved_max; /* RTCP */
        else
            id = rtsp_st->interleaved_min; /* RTP */
        interleave_header[0] = '$';
        interleave_header[1] = id;
        AV_WB16(interleave_header + 2, packet_len);
        ffurl_write(rt->rtsp_hd_out, interleaved_packet, 4 + packet_len);
        ptr += packet_len;
        size -= packet_len;
    }
    av_free(buf);
    return ffio_open_dyn_packet_buf(&rtpctx->pb, RTSP_TCP_MAX_PACKET_SIZE);
}

static int rtsp_write_packet(AVFormatContext *s, AVPacket *pkt)
{
    RTSPState *rt = s->priv_data;
    RTSPStream *rtsp_st;
    int n;
    struct pollfd p = {ffurl_get_file_handle(rt->rtsp_hd), POLLIN, 0};
    AVFormatContext *rtpctx;
    int ret;

    while (1) {
        n = poll(&p, 1, 0);
        if (n <= 0)
            break;
        if (p.revents & POLLIN) {
            RTSPMessageHeader reply;

            /* Don't let ff_rtsp_read_reply handle interleaved packets,
             * since it would block and wait for an RTSP reply on the socket
             * (which may not be coming any time soon) if it handles
             * interleaved packets internally. */
            ret = ff_rtsp_read_reply(s, &reply, NULL, 1, NULL);
            if (ret < 0)
                return AVERROR(EPIPE);
            if (ret == 1)
                ff_rtsp_skip_packet(s);
            /* XXX: parse message */
            if (rt->state != RTSP_STATE_STREAMING)
                return AVERROR(EPIPE);
        }
    }

    if (pkt->stream_index < 0 || pkt->stream_index >= rt->nb_rtsp_streams)
        return AVERROR_INVALIDDATA;
    rtsp_st = rt->rtsp_streams[pkt->stream_index];
    rtpctx = rtsp_st->transport_priv;

    ret = ff_write_chained(rtpctx, 0, pkt, s, 0);
    /* ff_write_chained does all the RTP packetization. If using TCP as
     * transport, rtpctx->pb is only a dyn_packet_buf that queues up the
     * packets, so we need to send them out on the TCP connection separately.
     */
    if (!ret && rt->lower_transport == RTSP_LOWER_TRANSPORT_TCP)
        ret = ff_rtsp_tcp_write_packet(s, rtsp_st);
    return ret;
}

static int rtsp_write_close(AVFormatContext *s)
{
    RTSPState *rt = s->priv_data;

    // If we want to send RTCP_BYE packets, these are sent by av_write_trailer.
    // Thus call this on all streams before doing the teardown. This is
    // done within ff_rtsp_undo_setup.
    ff_rtsp_undo_setup(s, 1);

    ff_rtsp_send_cmd_async(s, "TEARDOWN", rt->control_uri, NULL);

    ff_rtsp_close_streams(s);
    ff_rtsp_close_connections(s);
    ff_network_close();
    return 0;
}

AVOutputFormat ff_rtsp_muxer = {
    .name              = "rtsp",
    .long_name         = NULL_IF_CONFIG_SMALL("RTSP output"),
    .priv_data_size    = sizeof(RTSPState),
    .audio_codec       = AV_CODEC_ID_AAC,
    .video_codec       = AV_CODEC_ID_MPEG4,
    .write_header      = rtsp_write_header,
    .write_packet      = rtsp_write_packet,
    .write_trailer     = rtsp_write_close,
    .flags             = AVFMT_NOFILE | AVFMT_GLOBALHEADER,
    .priv_class        = &rtsp_muxer_class,
};