From d8b37973d2d9395665f2af8c5bc40bc3eb1cb48a Mon Sep 17 00:00:00 2001
From: Vivia Nikolaidou <vivia@ahiru.eu>
Date: Fri, 10 Jul 2020 21:14:01 +0300
Subject: [PATCH] tsmux: Fix PCR calculation for CBR live streams

Take the first ever timestamp as an offset

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1431>
---
 gst/mpegtsmux/tsmux/tsmux.c | 9 ++++++++-
 gst/mpegtsmux/tsmux/tsmux.h | 2 ++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/gst/mpegtsmux/tsmux/tsmux.c b/gst/mpegtsmux/tsmux/tsmux.c
index 2856d03469..647d6e5bb3 100644
--- a/gst/mpegtsmux/tsmux/tsmux.c
+++ b/gst/mpegtsmux/tsmux/tsmux.c
@@ -157,6 +157,8 @@ tsmux_new (void)
   mux->new_stream_func = (TsMuxNewStreamFunc) tsmux_stream_new;
   mux->new_stream_data = NULL;
 
+  mux->first_pcr_ts = G_MININT64;
+
   return mux;
 }
 
@@ -1252,7 +1254,12 @@ get_current_pcr (TsMux * mux, gint64 cur_ts)
   if (!mux->bitrate)
     return ts_to_pcr (cur_ts);
 
-  return ts_to_pcr (CLOCK_BASE) +
+  if (mux->first_pcr_ts == G_MININT64) {
+    g_assert (cur_ts != G_MININT64);
+    mux->first_pcr_ts = cur_ts;
+  }
+
+  return ts_to_pcr (mux->first_pcr_ts) +
       gst_util_uint64_scale (mux->n_bytes * 8, TSMUX_SYS_CLOCK_FREQ,
       mux->bitrate);
 }
diff --git a/gst/mpegtsmux/tsmux/tsmux.h b/gst/mpegtsmux/tsmux/tsmux.h
index 8dbb9dae62..9f067a3424 100644
--- a/gst/mpegtsmux/tsmux/tsmux.h
+++ b/gst/mpegtsmux/tsmux/tsmux.h
@@ -200,6 +200,8 @@ struct TsMux {
 
   /* For the per-PID continuity counter */
   guint8 pid_packet_counts[8192];
+
+  gint64 first_pcr_ts;
 };
 
 /* create/free new muxer session */