[Spice-devel] [spice-gtk 2/2] RFC: Allow to limit the latency introduced by lip sync

[Frediano Ziglio]

> 
> Hi
> 
> ----- Original Message -----
> > This patch allows to reduce the time the client wait to display frames.
> > It can make the lip sync not working but it allows to see the
> > video latency introduced by this code.
> > This patch is meant to be used mainly for debugging.
> 
> How does it help with debugging? I can't find a good reason to have a
> maximized delay for debugging reasons, or for user-experience, however a
> warning for delay > X seconds could be useful.
> 

- recently we are seeing some artifacts due to this delay and overlaying,
  removing the delay make easier to understand if the problem is related
  to this or other issues;
- we are testing guest encoding and we are experiencing a big lag. This
  avoid this part of the lag helping understand where the other part
  of the delay happens.

I'll add these to comment

Frediano

> > 
> > Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> > ---
> >  src/channel-display-gst.c   |  1 +
> >  src/channel-display-mjpeg.c | 14 ++++++++++++++
> >  src/channel-display-priv.h  |  3 +++
> >  3 files changed, 18 insertions(+)
> > 
> > diff --git a/src/channel-display-gst.c b/src/channel-display-gst.c
> > index 9c62e67..379c935 100644
> > --- a/src/channel-display-gst.c
> > +++ b/src/channel-display-gst.c
> > @@ -184,6 +184,7 @@ static void schedule_frame(SpiceGstDecoder *decoder)
> >  
> >          SpiceStreamDataHeader *op = spice_msg_in_parsed(frame->msg);
> >          gint32 time_diff = compute_mm_time_diff(op->multi_media_time,
> >          now);
> > +        time_diff = MIN(time_diff, max_frame_delay_ms);
> >          if (time_diff >= 0) {
> >              decoder->timer_id = g_timeout_add(time_diff,
> >                                                display_frame, decoder);
> > diff --git a/src/channel-display-mjpeg.c b/src/channel-display-mjpeg.c
> > index 1b7373b..5c778a9 100644
> > --- a/src/channel-display-mjpeg.c
> > +++ b/src/channel-display-mjpeg.c
> > @@ -182,6 +182,19 @@ static gboolean mjpeg_decoder_decode_frame(gpointer
> > video_decoder)
> >  
> >  /* ---------- VideoDecoder's queue scheduling ---------- */
> >  
> > +enum { MAX_DELAY_MS = 2000 };
> > +gint32 max_frame_delay_ms = MAX_DELAY_MS;
> > +
> > +SPICE_CONSTRUCTOR_FUNC(max_delay_init)
> > +{
> > +    const char *str_delay = g_getenv("SPICE_MAX_FRAME_DELAY");
> > +    if (str_delay) {
> > +        int delay = atoi(str_delay);
> > +        if (delay >= 0 && delay <= MAX_DELAY_MS)
> > +            max_frame_delay_ms = delay;
> > +    }
> > +}
> > +
> >  static void mjpeg_decoder_schedule(MJpegDecoder *decoder)
> >  {
> >      SPICE_DEBUG("%s", __FUNCTION__);
> > @@ -196,6 +209,7 @@ static void mjpeg_decoder_schedule(MJpegDecoder
> > *decoder)
> >          if (frame_msg) {
> >              SpiceStreamDataHeader *op = spice_msg_in_parsed(frame_msg);
> >              gint32 time_diff = compute_mm_time_diff(op->multi_media_time,
> >              time);
> > +            time_diff = MIN(time_diff, max_frame_delay_ms);
> >              if (time_diff >= 0) {
> >                  decoder->cur_frame_msg = frame_msg;
> >                  decoder->timer_id = g_timeout_add(time_diff,
> >                  mjpeg_decoder_decode_frame, decoder);
> > diff --git a/src/channel-display-priv.h b/src/channel-display-priv.h
> > index 3cd0727..1254f9d 100644
> > --- a/src/channel-display-priv.h
> > +++ b/src/channel-display-priv.h
> > @@ -157,6 +157,9 @@ static inline gint32 compute_mm_time_diff(guint32
> > time1,
> > guint32 time2)
> >      return (gint32) (guint32) (time1 - time2);
> >  }
> >  
> > +/* maximum delay for frames */
> > +extern gint32 max_frame_delay_ms;
> > +
> >  G_END_DECLS
> >  
> >  #endif // CHANNEL_DISPLAY_PRIV_H_