[Spice-devel] [PATCH spice-gtk] channel-display-gst: Avoid PTS to decrease

[Frediano Ziglio]

GStreamer does not accept PTS to decrease and set the new PTS
with the value of the previous one.
This causes our code to not match output frames with input ones.
Make sure PTS always increases (even if very slowly).

Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
---
 src/channel-display-gst.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

This should avoid the issues the following patch is trying
also to fix:
https://patchwork.freedesktop.org/patch/277721/

diff --git a/src/channel-display-gst.c b/src/channel-display-gst.c
index 4272ade8..7d7b435d 100644
--- a/src/channel-display-gst.c
+++ b/src/channel-display-gst.c
@@ -42,6 +42,8 @@ typedef struct SpiceGstDecoder {
     GstAppSink *appsink;
     GstElement *pipeline;
     GstClock *clock;
+    // minimum PTS attached to the next frame to avoid decreasing it
+    GstClockTime next_minimum_pts;
 
     /* ---------- Decoding and display queues ---------- */
 
@@ -657,9 +659,14 @@ static gboolean spice_gst_decoder_queue_frame(VideoDecoder *video_decoder,
                                                     frame->data, frame->size, 0, frame->size,
                                                     frame, (GDestroyNotify) spice_frame_free);
 
+    GstClockTime pts = gst_clock_get_time(decoder->clock) -
+                       gst_element_get_base_time(decoder->pipeline) +
+                       ((uint64_t)MAX(0, latency)) * 1000 * 1000;
+    pts = MAX(pts, decoder->next_minimum_pts);
+    decoder->next_minimum_pts = pts + 1;
     GST_BUFFER_DURATION(buffer) = GST_CLOCK_TIME_NONE;
     GST_BUFFER_DTS(buffer) = GST_CLOCK_TIME_NONE;
-    GST_BUFFER_PTS(buffer) = gst_clock_get_time(decoder->clock) - gst_element_get_base_time(decoder->pipeline) + ((uint64_t)MAX(0, latency)) * 1000 * 1000;
+    GST_BUFFER_PTS(buffer) = pts;
 
     SpiceGstFrame *gst_frame = create_gst_frame(buffer, frame);
     g_mutex_lock(&decoder->queues_mutex);
-- 
2.20.1