From ab587f39b2201238594384ad58a4224233fb315b Mon Sep 17 00:00:00 2001 From: Martin Storsjö Date: Fri, 7 Dec 2012 11:12:28 +0200 Subject: rtpenc: Start the sequence numbers from a random offset MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Expose the current sequence number via an AVOption - this can be used both for setting the initial sequence number, or for querying the current number. Signed-off-by: Martin Storsjö --- libavformat/rtpenc.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'libavformat/rtpenc.c') diff --git a/libavformat/rtpenc.c b/libavformat/rtpenc.c index 0f5307d719..d0140ee6b8 100644 --- a/libavformat/rtpenc.c +++ b/libavformat/rtpenc.c @@ -35,6 +35,7 @@ static const AVOption options[] = { { "payload_type", "Specify RTP payload type", offsetof(RTPMuxContext, payload_type), AV_OPT_TYPE_INT, {.i64 = -1 }, -1, 127, AV_OPT_FLAG_ENCODING_PARAM }, { "ssrc", "Stream identifier", offsetof(RTPMuxContext, ssrc), AV_OPT_TYPE_INT, { .i64 = 0 }, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM }, { "cname", "CNAME to include in RTCP SR packets", offsetof(RTPMuxContext, cname), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, AV_OPT_FLAG_ENCODING_PARAM }, + { "seq", "Starting sequence number", offsetof(RTPMuxContext, seq), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 65535, AV_OPT_FLAG_ENCODING_PARAM }, { NULL }, }; @@ -124,6 +125,13 @@ static int rtp_write_header(AVFormatContext *s1) /* Round the NTP time to whole milliseconds. */ s->first_rtcp_ntp_time = (s1->start_time_realtime / 1000) * 1000 + NTP_OFFSET_US; + // Pick a random sequence start number, but in the lower end of the + // available range, so that any wraparound doesn't happen immediately. + // (Immediate wraparound would be an issue for SRTP.) + if (s->seq < 0) + s->seq = av_get_random_seed() & 0x0fff; + else + s->seq &= 0xffff; // Use the given parameter, wrapped to the right interval if (s1->packet_size) { if (s1->pb->max_packet_size) @@ -309,7 +317,7 @@ void ff_rtp_send_data(AVFormatContext *s1, const uint8_t *buf1, int len, int m) avio_write(s1->pb, buf1, len); avio_flush(s1->pb); - s->seq++; + s->seq = (s->seq + 1) & 0xffff; s->octet_count += len; s->packet_count++; } -- cgit v1.2.3