Bring back the lightweight RTCP sender

modules/stream_out/Modules.am

@@ -6,7 +6,7 @@ SOURCES_stream_out_duplicate = duplicate.c
 SOURCES_stream_out_es = es.c
 SOURCES_stream_out_display = display.c
 SOURCES_stream_out_gather = gather.c
-SOURCES_stream_out_rtp = rtp.c rtp.h rtsp.c
+SOURCES_stream_out_rtp = rtp.h rtp.c rtcp.c rtsp.c
 SOURCES_stream_out_switcher = switcher.c
 SOURCES_stream_out_bridge = bridge.c
 SOURCES_stream_out_mosaic_bridge = mosaic_bridge.c

modules/stream_out/rtcp.c

+/*****************************************************************************
+ * rtcp.c: RTCP stream output support
+ *****************************************************************************
+ * Copyright © 2007 Rémi Denis-Courmont
+ * $Id$
+ *
+ * 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 2.1 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Preamble
+ *****************************************************************************/
+
+#include <vlc/vlc.h>
+#include <vlc_block.h>
+
+#include <vlc_network.h>
+
+
+#include <vlc_url.h>
+#include <vlc_sout.h>
+#include "rtp.h"
+
+/*
+ * NOTE on RTCP implementation:
+ * - there is a single sender (us), no conferencing here! => n = sender = 1,
+ * - as such we need not bother to include Receiver Reports,
+ * - in unicast case, there is a single receiver => members = 1 + 1 = 2,
+ *   and obviously n > 25% of members,
+ * - in multicast case, we do not want to maintain the number of receivers
+ *   and we assume it is big (i.e. than 3) because that's what broadcasting is
+ *   all about,
+ * - it is assumed we_sent = true (could be wrong), since we are THE sender,
+ * - we always send SR + SDES, while running,
+ * - FIXME: we do not implement separate rate limiting for SDES,
+ * - we do not implement any profile-specific extensions for the time being.
+ */
+struct rtcp_sender_t
+{
+    size_t   length;  /* RTCP packet length */
+    uint8_t  payload[28 + 8 + (2 * 257)];
+    int      handle;  /* RTCP socket handler */
+
+    uint32_t packets; /* RTP packets sent */
+    uint32_t bytes;   /* RTP bytes sent */
+    unsigned counter; /* RTP packets sent since last RTCP packet */
+};
+
+
+rtcp_sender_t *OpenRTCP (vlc_object_t *obj, int rtp_fd,
+                         int proto, uint16_t dport)
+{
+    rtcp_sender_t *rtcp;
+    uint8_t *ptr;
+    char src[NI_MAXNUMERICHOST], dst[NI_MAXNUMERICHOST];
+    int sport;
+    int fd;
+
+    if (net_GetSockAddress (rtp_fd, src, &sport)
+     || net_GetPeerAddress (rtp_fd, dst, NULL))
+        return NULL;
+
+    sport++;
+    fd = net_OpenDgram (obj, src, sport, dst, dport, AF_UNSPEC, proto);
+    if (fd == -1)
+        return NULL;
+
+    rtcp = malloc (sizeof (*rtcp));
+    if (rtcp == NULL)
+    {
+        net_Close (fd);
+        return NULL;
+    }
+
+    rtcp->handle = fd;
+    rtcp->bytes = rtcp->packets = rtcp->counter = 0;
+
+    ptr = (uint8_t *)strchr (src, '%');
+    if (ptr != NULL)
+        *ptr = '\0'; /* remove scope ID frop IPv6 addresses */
+
+    ptr = rtcp->payload;
+
+    /* Sender report */
+    ptr[0] = 2 << 6; /* V = 2, P = RC = 0 */
+    ptr[1] = 200; /* payload type: Sender Report */
+    SetWBE (ptr + 2, 6); /* length = 6 (7 double words) */
+    memset (ptr + 4, 0, 4); /* SSRC unknown yet */
+    SetQWBE (ptr + 8, NTPtime64 ());
+    memset (ptr + 16, 0, 12); /* timestamp and counters */
+    ptr += 28;
+
+    /* Source description */
+    uint8_t *sdes = ptr;
+    ptr[0] = (2 << 6) | 1; /* V = 2, P = 0, SC = 1 */
+    ptr[1] = 202; /* payload type: Source Description */
+    uint8_t *lenptr = ptr + 2;
+    memset (ptr + 4, 0, 4); /* SSRC unknown yet */
+    ptr += 8;
+
+    ptr[0] = 1; /* CNAME - mandatory */
+    assert (NI_MAXNUMERICHOST <= 256);
+    ptr[1] = strlen (src);
+    memcpy (ptr + 2, src, ptr[1]);
+    ptr += ptr[1] + 2;
+
+    static const char tool[] = PACKAGE_STRING;
+    ptr[0] = 6; /* TOOL */
+    ptr[1] = (sizeof (tool) > 256) ? 255 : (sizeof (tool) - 1);
+    memcpy (ptr + 2, tool, ptr[1]);
+    ptr += ptr[1] + 2;
+
+    while ((ptr - sdes) & 3) /* 32-bits padding */
+        *ptr++ = 0;
+    SetWBE (lenptr, ptr - sdes);
+
+    rtcp->length = ptr - rtcp->payload;
+    return VLC_SUCCESS;
+}
+
+
+void CloseRTCP (rtcp_sender_t *rtcp)
+{
+    if (rtcp == NULL)
+        return;
+
+    uint8_t *ptr = rtcp->payload;
+    /* Bye */
+    ptr[0] = (2 << 6) | 1; /* V = 2, P = 0, SC = 1 */
+    ptr[1] = 203; /* payload type: Bye */
+    SetWBE (ptr + 2, 1);
+    /* SSRC is already there :) */
+
+    /* We are THE sender, so we are more important than anybody else, so
+     * we can afford not to check bandwidth constraints here. */
+    send (rtcp->handle, rtcp->payload, 8, 0);
+    net_Close (rtcp->handle);
+}
+
+
+void SendRTCP (rtcp_sender_t *restrict rtcp, const block_t *rtp)
+{
+    if ((rtcp == NULL) /* RTCP sender off */
+     || (rtp->i_buffer < 12)) /* too short RTP packet */
+        return;
+
+    /* Updates statistics */
+    rtcp->packets++;
+    rtcp->bytes += rtp->i_buffer;
+    rtcp->counter += rtp->i_buffer;
+
+    /* 1.25% rate limit */
+    if ((rtcp->counter / 80) < rtcp->length)
+        return;
+
+    uint8_t *ptr = rtcp->payload;
+    uint32_t last = GetDWBE (ptr + 8); // last RTCP SR send time
+    uint64_t now64 = NTPtime64 ();
+    if ((now64 >> 32) < (last + 5))
+        return; // no more than one SR every 5 seconds
+
+    memcpy (ptr + 4, rtp->p_buffer + 8, 4); /* SR SSRC */
+    SetQWBE (ptr + 8, now64);
+    memcpy (ptr + 16, rtp->p_buffer + 4, 4); /* RTP timestamp */
+    SetDWBE (ptr + 20, rtcp->packets);
+    SetDWBE (ptr + 24, rtcp->bytes);
+    memcpy (ptr + 28 + 4, rtp->p_buffer + 8, 4); /* SDES SSRC */
+
+    if (send (rtcp->handle, ptr, rtcp->length, 0) == (ssize_t)rtcp->length)
+        rtcp->counter = 0;
+}

modules/stream_out/rtp.h

@@ -39,3 +39,9 @@ char *SDPGenerate( const sout_stream_t *p_stream, const char *rtsp_url );
 int rtp_add_sink( sout_stream_id_t *id, int fd );
 void rtp_del_sink( sout_stream_id_t *id, int fd );
 
+/* RTCP */
+typedef struct rtcp_sender_t rtcp_sender_t;
+rtcp_sender_t *OpenRTCP (vlc_object_t *obj, int rtp_fd,
+                         int proto, uint16_t dport);
+void CloseRTCP (rtcp_sender_t *rtcp);
+void SendRTCP (rtcp_sender_t *restrict rtcp, const block_t *rtp);