[FFmpeg-devel] [PATCH] avformat/rtsp: Add -first_rtcp_ntp_time_path option to write the first NTP time to a file.

[Jonathan Viney]

Apologies, here is the patch in text/plain.

On Thu, May 23, 2019 at 4:44 PM Jonathan Viney <jonathan.viney at gmail.com>
wrote:

> Hi,
>
> The NTP time from the first RTCP packet is currently extracted in
> libavformat/rtsp.c and stored in AVFormatContext.start_time_realtime.
> However, there is no way to access this value when using ffmpeg from the
> commandline.
>
> This patch adds an option when using an RTSP input to write the value to a
> file when it is received.
>
> Eg:
> ffmpeg -first_rtcp_ntp_time_path out.mp4.ntp -i rtsp://10.0.0.1/ -c copy
> out.mp4
>
> Regards,
> -Jonathan.
>
-------------- next part --------------
From e16826736640f132f0d3a6f170337ab9696e0038 Mon Sep 17 00:00:00 2001
From: Jonathan Viney <jonathan.viney at gmail.com>
Date: Thu, 23 May 2019 14:24:16 +1200
Subject: [PATCH] avformat/rtsp: add -first_rtcp_ntp_time_path option to write
 the first NTP time to a file.

Signed-off-by: Jonathan Viney <jonathan.viney at gmail.com>
---
 libavformat/rtsp.c | 16 ++++++++++++++++
 libavformat/rtsp.h |  6 ++++++
 2 files changed, 22 insertions(+)

diff --git a/libavformat/rtsp.c b/libavformat/rtsp.c
index c153cac88b..4b048701e2 100644
--- a/libavformat/rtsp.c
+++ b/libavformat/rtsp.c
@@ -96,6 +96,7 @@ const AVOption ff_rtsp_options[] = {
     { "min_port", "set minimum local UDP port", OFFSET(rtp_port_min), AV_OPT_TYPE_INT, {.i64 = RTSP_RTP_PORT_MIN}, 0, 65535, DEC|ENC },
     { "max_port", "set maximum local UDP port", OFFSET(rtp_port_max), AV_OPT_TYPE_INT, {.i64 = RTSP_RTP_PORT_MAX}, 0, 65535, DEC|ENC },
     { "listen_timeout", "set maximum timeout (in seconds) to wait for incoming connections (-1 is infinite, imply flag listen)", OFFSET(initial_timeout), AV_OPT_TYPE_INT, {.i64 = -1}, INT_MIN, INT_MAX, DEC },
+    { "first_rtcp_ntp_time_path", "path to write first NTP time (in microseconds) received in RTCP packet", OFFSET(first_rtcp_ntp_time_path), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, DEC },
 #if FF_API_OLD_RTSP_OPTIONS
     { "timeout", "set maximum timeout (in seconds) to wait for incoming connections (-1 is infinite, imply flag listen) (deprecated, use listen_timeout)", OFFSET(initial_timeout), AV_OPT_TYPE_INT, {.i64 = -1}, INT_MIN, INT_MAX, DEC },
     { "stimeout", "set timeout (in microseconds) of socket TCP I/O operations", OFFSET(stimeout), AV_OPT_TYPE_INT, {.i64 = 0}, INT_MIN, INT_MAX, DEC },
@@ -2256,6 +2257,21 @@ redo:
                                         (uint64_t) rtpctx->st->time_base.num * 1000000,
                                                    rtpctx->st->time_base.den);
                     }
+
+                    // Write the NTP start time
+                    if (rt->first_rtcp_ntp_time_path) {
+                        AVIOContext *ioctx = NULL;
+                        int ret;
+                        ret = avio_open(&ioctx, rt->first_rtcp_ntp_time_path, AVIO_FLAG_WRITE);
+                        if (ret < 0) {
+                            av_log(s, AV_LOG_WARNING, "unable to open %s to write first rtcp ntp time\n", rt->first_rtcp_ntp_time_path);
+                        } else {
+                            char buf[21] = "";
+                            av_strlcatf(buf, sizeof(buf), "%lld", s->start_time_realtime);
+                            avio_write(ioctx, buf, strlen(buf));
+                            avio_closep(&ioctx);
+                        }
+                    }
                 }
             }
             if (ret == -RTCP_BYE) {
diff --git a/libavformat/rtsp.h b/libavformat/rtsp.h
index 54a9a30c16..4df24b743a 100644
--- a/libavformat/rtsp.h
+++ b/libavformat/rtsp.h
@@ -408,6 +408,12 @@ typedef struct RTSPState {
      */
     char *user_agent;
 
+    /**
+     * Path to write the first RTCP unix time in microseconds, if
+     * it is received as part of the stream.
+     */
+    char *first_rtcp_ntp_time_path;
+
     char default_lang[4];
     int buffer_size;
     int pkt_size;
-- 
2.21.0