Re: [Spice-devel] [spice-gtk v2 1/2] Fix possible multimedia time overflow

[Christophe de Dinechin]

> On 16 Mar 2017, at 11:49, Marc-André Lureau  > wrote:
> 
> Hi
> 
> - Original Message -
>> The multimedia time can easily overflow as is encoded in an
>> unsigned 32 bit and have a unit of milliseconds so it wrap
>> up every 49 days. Use some math that allow the number to overflow
>> without issues.
>> This could caused the client to stop handling streaming and
>> starting only queueing.
>> 
>> Signed-off-by: Frediano Ziglio > >
>> ---
>> This patch should be applied independently on 2/2 as intended to be
>> merged upstream as a fix while 2/2 depends on this as it change same
>> code portions.
>> ---
>> src/channel-display-gst.c   | 11 ++-
>> src/channel-display-mjpeg.c | 14 --
>> src/channel-display-priv.h  | 19 +++
>> 3 files changed, 33 insertions(+), 11 deletions(-)
>> 
>> diff --git a/src/channel-display-gst.c b/src/channel-display-gst.c
>> index c4190b2..9c62e67 100644
>> --- a/src/channel-display-gst.c
>> +++ b/src/channel-display-gst.c
>> @@ -183,8 +183,9 @@ static void schedule_frame(SpiceGstDecoder *decoder)
>> }
>> 
>> SpiceStreamDataHeader *op = spice_msg_in_parsed(frame->msg);
>> -if (now < op->multi_media_time) {
>> -decoder->timer_id = g_timeout_add(op->multi_media_time - now,
>> +gint32 time_diff = compute_mm_time_diff(op->multi_media_time, now);
>> +if (time_diff >= 0) {
>> +decoder->timer_id = g_timeout_add(time_diff,
>>   display_frame, decoder);
>> } else if (g_queue_get_length(decoder->display_queue) == 1) {
>> /* Still attempt to display the least out of date frame so the
>> @@ -192,8 +193,8 @@ static void schedule_frame(SpiceGstDecoder *decoder)
>>  */
>> decoder->timer_id = g_timeout_add(0, display_frame, decoder);
>> } else {
>> -SPICE_DEBUG("%s: rendering too late by %u ms (ts: %u, mmtime:
>> %u), dropping",
>> -__FUNCTION__, now - op->multi_media_time,
>> +SPICE_DEBUG("%s: rendering too late by %d ms (ts: %u, mmtime:
>> %u), dropping",
>> +__FUNCTION__, -time_diff,
>> op->multi_media_time, now);
>> stream_dropped_frame_on_playback(decoder->base.stream);
>> g_queue_pop_head(decoder->display_queue);
>> @@ -431,7 +432,7 @@ static gboolean
>> spice_gst_decoder_queue_frame(VideoDecoder *video_decoder,
>> }
>> 
>> SpiceStreamDataHeader *frame_op = spice_msg_in_parsed(frame_msg);
>> -if (frame_op->multi_media_time < decoder->last_mm_time) {
>> +if (compute_mm_time_diff(frame_op->multi_media_time,
>> decoder->last_mm_time) < 0) {
>> SPICE_DEBUG("new-frame-time < last-frame-time (%u < %u):"
>> " resetting stream, id %u",
>> frame_op->multi_media_time,
>> diff --git a/src/channel-display-mjpeg.c b/src/channel-display-mjpeg.c
>> index 722494e..1b7373b 100644
>> --- a/src/channel-display-mjpeg.c
>> +++ b/src/channel-display-mjpeg.c
>> @@ -195,15 +195,15 @@ static void mjpeg_decoder_schedule(MJpegDecoder
>> *decoder)
>> do {
>> if (frame_msg) {
>> SpiceStreamDataHeader *op = spice_msg_in_parsed(frame_msg);
>> -if (time <= op->multi_media_time) {
>> -guint32 d = op->multi_media_time - time;
>> +gint32 time_diff = compute_mm_time_diff(op->multi_media_time,
>> time);
>> +if (time_diff >= 0) {
>> decoder->cur_frame_msg = frame_msg;
>> -decoder->timer_id = g_timeout_add(d,
>> mjpeg_decoder_decode_frame, decoder);
>> +decoder->timer_id = g_timeout_add(time_diff,
>> mjpeg_decoder_decode_frame, decoder);
>> break;
>> }
>> 
>> -SPICE_DEBUG("%s: rendering too late by %u ms (ts: %u, mmtime:
>> %u), dropping ",
>> -__FUNCTION__, time - op->multi_media_time,
>> +SPICE_DEBUG("%s: rendering too late by %d ms (ts: %u, mmtime:
>> %u), dropping ",
>> +__FUNCTION__, -time_diff,
>> op->multi_media_time, time);
>> stream_dropped_frame_on_playback(decoder->base.stream);
>> spice_msg_in_unref(frame_msg);
>> @@ -249,7 +249,9 @@ static gboolean mjpeg_decoder_queue_frame(VideoDecoder
>> *video_decoder,
>> SpiceStreamDataHeader *last_op, *frame_op;
>> last_op = spice_msg_in_parsed(last_msg);
>> frame_op = spice_msg_in_parsed(frame_msg);
>> -if (frame_op->multi_media_time < last_op->multi_media_time) {
>> +gint32 time_diff =
>> +compute_mm_time_diff(frame_op->multi_media_time,
>> last_op->multi_media_time);
>> +if (time_diff < 0) {
>> /* This should really not happen */
>> 

Re: [Spice-devel] [spice-gtk v2 1/2] Fix possible multimedia time overflow

[Marc-André Lureau]

Hi

- Original Message -
> > 
> > Hi
> > 
> > - Original Message -
> > > The multimedia time can easily overflow as is encoded in an
> > > unsigned 32 bit and have a unit of milliseconds so it wrap
> > > up every 49 days. Use some math that allow the number to overflow
> > > without issues.
> > > This could caused the client to stop handling streaming and
> > > starting only queueing.
> > > 
> > > Signed-off-by: Frediano Ziglio 
> > > ---
> > > This patch should be applied independently on 2/2 as intended to be
> > > merged upstream as a fix while 2/2 depends on this as it change same
> > > code portions.
> > > ---
> > >  src/channel-display-gst.c   | 11 ++-
> > >  src/channel-display-mjpeg.c | 14 --
> > >  src/channel-display-priv.h  | 19 +++
> > >  3 files changed, 33 insertions(+), 11 deletions(-)
> > > 
> > > diff --git a/src/channel-display-gst.c b/src/channel-display-gst.c
> > > index c4190b2..9c62e67 100644
> > > --- a/src/channel-display-gst.c
> > > +++ b/src/channel-display-gst.c
> > > @@ -183,8 +183,9 @@ static void schedule_frame(SpiceGstDecoder *decoder)
> > >  }
> > >  
> > >  SpiceStreamDataHeader *op = spice_msg_in_parsed(frame->msg);
> > > -if (now < op->multi_media_time) {
> > > -decoder->timer_id = g_timeout_add(op->multi_media_time -
> > > now,
> > > +gint32 time_diff = compute_mm_time_diff(op->multi_media_time,
> > > now);
> > > +if (time_diff >= 0) {
> > > +decoder->timer_id = g_timeout_add(time_diff,
> > >display_frame, decoder);
> > >  } else if (g_queue_get_length(decoder->display_queue) == 1) {
> > >  /* Still attempt to display the least out of date frame so
> > >  the
> > > @@ -192,8 +193,8 @@ static void schedule_frame(SpiceGstDecoder *decoder)
> > >   */
> > >  decoder->timer_id = g_timeout_add(0, display_frame,
> > >  decoder);
> > >  } else {
> > > -SPICE_DEBUG("%s: rendering too late by %u ms (ts: %u,
> > > mmtime:
> > > %u), dropping",
> > > -__FUNCTION__, now - op->multi_media_time,
> > > +SPICE_DEBUG("%s: rendering too late by %d ms (ts: %u,
> > > mmtime:
> > > %u), dropping",
> > > +__FUNCTION__, -time_diff,
> > >  op->multi_media_time, now);
> > >  stream_dropped_frame_on_playback(decoder->base.stream);
> > >  g_queue_pop_head(decoder->display_queue);
> > > @@ -431,7 +432,7 @@ static gboolean
> > > spice_gst_decoder_queue_frame(VideoDecoder *video_decoder,
> > >  }
> > >  
> > >  SpiceStreamDataHeader *frame_op = spice_msg_in_parsed(frame_msg);
> > > -if (frame_op->multi_media_time < decoder->last_mm_time) {
> > > +if (compute_mm_time_diff(frame_op->multi_media_time,
> > > decoder->last_mm_time) < 0) {
> > >  SPICE_DEBUG("new-frame-time < last-frame-time (%u < %u):"
> > >  " resetting stream, id %u",
> > >  frame_op->multi_media_time,
> > > diff --git a/src/channel-display-mjpeg.c b/src/channel-display-mjpeg.c
> > > index 722494e..1b7373b 100644
> > > --- a/src/channel-display-mjpeg.c
> > > +++ b/src/channel-display-mjpeg.c
> > > @@ -195,15 +195,15 @@ static void mjpeg_decoder_schedule(MJpegDecoder
> > > *decoder)
> > >  do {
> > >  if (frame_msg) {
> > >  SpiceStreamDataHeader *op = spice_msg_in_parsed(frame_msg);
> > > -if (time <= op->multi_media_time) {
> > > -guint32 d = op->multi_media_time - time;
> > > +gint32 time_diff =
> > > compute_mm_time_diff(op->multi_media_time,
> > > time);
> > > +if (time_diff >= 0) {
> > >  decoder->cur_frame_msg = frame_msg;
> > > -decoder->timer_id = g_timeout_add(d,
> > > mjpeg_decoder_decode_frame, decoder);
> > > +decoder->timer_id = g_timeout_add(time_diff,
> > > mjpeg_decoder_decode_frame, decoder);
> > >  break;
> > >  }
> > >  
> > > -SPICE_DEBUG("%s: rendering too late by %u ms (ts: %u,
> > > mmtime:
> > > %u), dropping ",
> > > -__FUNCTION__, time - op->multi_media_time,
> > > +SPICE_DEBUG("%s: rendering too late by %d ms (ts: %u,
> > > mmtime:
> > > %u), dropping ",
> > > +__FUNCTION__, -time_diff,
> > >  op->multi_media_time, time);
> > >  stream_dropped_frame_on_playback(decoder->base.stream);
> > >  spice_msg_in_unref(frame_msg);
> > > @@ -249,7 +249,9 @@ static gboolean
> > > mjpeg_decoder_queue_frame(VideoDecoder
> > > *video_decoder,
> > >  SpiceStreamDataHeader *last_op, *frame_op;
> > >  last_op = spice_msg_in_parsed(last_msg);
> > >  frame_op = spice_msg_in_parsed(frame_msg);
> > > - 

Re: [Spice-devel] [spice-gtk v2 1/2] Fix possible multimedia time overflow

[Frediano Ziglio]

> 
> Hi
> 
> - Original Message -
> > The multimedia time can easily overflow as is encoded in an
> > unsigned 32 bit and have a unit of milliseconds so it wrap
> > up every 49 days. Use some math that allow the number to overflow
> > without issues.
> > This could caused the client to stop handling streaming and
> > starting only queueing.
> > 
> > Signed-off-by: Frediano Ziglio 
> > ---
> > This patch should be applied independently on 2/2 as intended to be
> > merged upstream as a fix while 2/2 depends on this as it change same
> > code portions.
> > ---
> >  src/channel-display-gst.c   | 11 ++-
> >  src/channel-display-mjpeg.c | 14 --
> >  src/channel-display-priv.h  | 19 +++
> >  3 files changed, 33 insertions(+), 11 deletions(-)
> > 
> > diff --git a/src/channel-display-gst.c b/src/channel-display-gst.c
> > index c4190b2..9c62e67 100644
> > --- a/src/channel-display-gst.c
> > +++ b/src/channel-display-gst.c
> > @@ -183,8 +183,9 @@ static void schedule_frame(SpiceGstDecoder *decoder)
> >  }
> >  
> >  SpiceStreamDataHeader *op = spice_msg_in_parsed(frame->msg);
> > -if (now < op->multi_media_time) {
> > -decoder->timer_id = g_timeout_add(op->multi_media_time - now,
> > +gint32 time_diff = compute_mm_time_diff(op->multi_media_time,
> > now);
> > +if (time_diff >= 0) {
> > +decoder->timer_id = g_timeout_add(time_diff,
> >display_frame, decoder);
> >  } else if (g_queue_get_length(decoder->display_queue) == 1) {
> >  /* Still attempt to display the least out of date frame so the
> > @@ -192,8 +193,8 @@ static void schedule_frame(SpiceGstDecoder *decoder)
> >   */
> >  decoder->timer_id = g_timeout_add(0, display_frame, decoder);
> >  } else {
> > -SPICE_DEBUG("%s: rendering too late by %u ms (ts: %u, mmtime:
> > %u), dropping",
> > -__FUNCTION__, now - op->multi_media_time,
> > +SPICE_DEBUG("%s: rendering too late by %d ms (ts: %u, mmtime:
> > %u), dropping",
> > +__FUNCTION__, -time_diff,
> >  op->multi_media_time, now);
> >  stream_dropped_frame_on_playback(decoder->base.stream);
> >  g_queue_pop_head(decoder->display_queue);
> > @@ -431,7 +432,7 @@ static gboolean
> > spice_gst_decoder_queue_frame(VideoDecoder *video_decoder,
> >  }
> >  
> >  SpiceStreamDataHeader *frame_op = spice_msg_in_parsed(frame_msg);
> > -if (frame_op->multi_media_time < decoder->last_mm_time) {
> > +if (compute_mm_time_diff(frame_op->multi_media_time,
> > decoder->last_mm_time) < 0) {
> >  SPICE_DEBUG("new-frame-time < last-frame-time (%u < %u):"
> >  " resetting stream, id %u",
> >  frame_op->multi_media_time,
> > diff --git a/src/channel-display-mjpeg.c b/src/channel-display-mjpeg.c
> > index 722494e..1b7373b 100644
> > --- a/src/channel-display-mjpeg.c
> > +++ b/src/channel-display-mjpeg.c
> > @@ -195,15 +195,15 @@ static void mjpeg_decoder_schedule(MJpegDecoder
> > *decoder)
> >  do {
> >  if (frame_msg) {
> >  SpiceStreamDataHeader *op = spice_msg_in_parsed(frame_msg);
> > -if (time <= op->multi_media_time) {
> > -guint32 d = op->multi_media_time - time;
> > +gint32 time_diff = compute_mm_time_diff(op->multi_media_time,
> > time);
> > +if (time_diff >= 0) {
> >  decoder->cur_frame_msg = frame_msg;
> > -decoder->timer_id = g_timeout_add(d,
> > mjpeg_decoder_decode_frame, decoder);
> > +decoder->timer_id = g_timeout_add(time_diff,
> > mjpeg_decoder_decode_frame, decoder);
> >  break;
> >  }
> >  
> > -SPICE_DEBUG("%s: rendering too late by %u ms (ts: %u, mmtime:
> > %u), dropping ",
> > -__FUNCTION__, time - op->multi_media_time,
> > +SPICE_DEBUG("%s: rendering too late by %d ms (ts: %u, mmtime:
> > %u), dropping ",
> > +__FUNCTION__, -time_diff,
> >  op->multi_media_time, time);
> >  stream_dropped_frame_on_playback(decoder->base.stream);
> >  spice_msg_in_unref(frame_msg);
> > @@ -249,7 +249,9 @@ static gboolean mjpeg_decoder_queue_frame(VideoDecoder
> > *video_decoder,
> >  SpiceStreamDataHeader *last_op, *frame_op;
> >  last_op = spice_msg_in_parsed(last_msg);
> >  frame_op = spice_msg_in_parsed(frame_msg);
> > -if (frame_op->multi_media_time < last_op->multi_media_time) {
> > +gint32 time_diff =
> > +compute_mm_time_diff(frame_op->multi_media_time,
> > last_op->multi_media_time);
> > +if (time_diff < 0) {
> >  /* This should really not happen */
> >  

Re: [Spice-devel] [spice-gtk v2 1/2] Fix possible multimedia time overflow

[Marc-André Lureau]

Hi

- Original Message -
> The multimedia time can easily overflow as is encoded in an
> unsigned 32 bit and have a unit of milliseconds so it wrap
> up every 49 days. Use some math that allow the number to overflow
> without issues.
> This could caused the client to stop handling streaming and
> starting only queueing.
> 
> Signed-off-by: Frediano Ziglio 
> ---
> This patch should be applied independently on 2/2 as intended to be
> merged upstream as a fix while 2/2 depends on this as it change same
> code portions.
> ---
>  src/channel-display-gst.c   | 11 ++-
>  src/channel-display-mjpeg.c | 14 --
>  src/channel-display-priv.h  | 19 +++
>  3 files changed, 33 insertions(+), 11 deletions(-)
> 
> diff --git a/src/channel-display-gst.c b/src/channel-display-gst.c
> index c4190b2..9c62e67 100644
> --- a/src/channel-display-gst.c
> +++ b/src/channel-display-gst.c
> @@ -183,8 +183,9 @@ static void schedule_frame(SpiceGstDecoder *decoder)
>  }
>  
>  SpiceStreamDataHeader *op = spice_msg_in_parsed(frame->msg);
> -if (now < op->multi_media_time) {
> -decoder->timer_id = g_timeout_add(op->multi_media_time - now,
> +gint32 time_diff = compute_mm_time_diff(op->multi_media_time, now);
> +if (time_diff >= 0) {
> +decoder->timer_id = g_timeout_add(time_diff,
>display_frame, decoder);
>  } else if (g_queue_get_length(decoder->display_queue) == 1) {
>  /* Still attempt to display the least out of date frame so the
> @@ -192,8 +193,8 @@ static void schedule_frame(SpiceGstDecoder *decoder)
>   */
>  decoder->timer_id = g_timeout_add(0, display_frame, decoder);
>  } else {
> -SPICE_DEBUG("%s: rendering too late by %u ms (ts: %u, mmtime:
> %u), dropping",
> -__FUNCTION__, now - op->multi_media_time,
> +SPICE_DEBUG("%s: rendering too late by %d ms (ts: %u, mmtime:
> %u), dropping",
> +__FUNCTION__, -time_diff,
>  op->multi_media_time, now);
>  stream_dropped_frame_on_playback(decoder->base.stream);
>  g_queue_pop_head(decoder->display_queue);
> @@ -431,7 +432,7 @@ static gboolean
> spice_gst_decoder_queue_frame(VideoDecoder *video_decoder,
>  }
>  
>  SpiceStreamDataHeader *frame_op = spice_msg_in_parsed(frame_msg);
> -if (frame_op->multi_media_time < decoder->last_mm_time) {
> +if (compute_mm_time_diff(frame_op->multi_media_time,
> decoder->last_mm_time) < 0) {
>  SPICE_DEBUG("new-frame-time < last-frame-time (%u < %u):"
>  " resetting stream, id %u",
>  frame_op->multi_media_time,
> diff --git a/src/channel-display-mjpeg.c b/src/channel-display-mjpeg.c
> index 722494e..1b7373b 100644
> --- a/src/channel-display-mjpeg.c
> +++ b/src/channel-display-mjpeg.c
> @@ -195,15 +195,15 @@ static void mjpeg_decoder_schedule(MJpegDecoder
> *decoder)
>  do {
>  if (frame_msg) {
>  SpiceStreamDataHeader *op = spice_msg_in_parsed(frame_msg);
> -if (time <= op->multi_media_time) {
> -guint32 d = op->multi_media_time - time;
> +gint32 time_diff = compute_mm_time_diff(op->multi_media_time,
> time);
> +if (time_diff >= 0) {
>  decoder->cur_frame_msg = frame_msg;
> -decoder->timer_id = g_timeout_add(d,
> mjpeg_decoder_decode_frame, decoder);
> +decoder->timer_id = g_timeout_add(time_diff,
> mjpeg_decoder_decode_frame, decoder);
>  break;
>  }
>  
> -SPICE_DEBUG("%s: rendering too late by %u ms (ts: %u, mmtime:
> %u), dropping ",
> -__FUNCTION__, time - op->multi_media_time,
> +SPICE_DEBUG("%s: rendering too late by %d ms (ts: %u, mmtime:
> %u), dropping ",
> +__FUNCTION__, -time_diff,
>  op->multi_media_time, time);
>  stream_dropped_frame_on_playback(decoder->base.stream);
>  spice_msg_in_unref(frame_msg);
> @@ -249,7 +249,9 @@ static gboolean mjpeg_decoder_queue_frame(VideoDecoder
> *video_decoder,
>  SpiceStreamDataHeader *last_op, *frame_op;
>  last_op = spice_msg_in_parsed(last_msg);
>  frame_op = spice_msg_in_parsed(frame_msg);
> -if (frame_op->multi_media_time < last_op->multi_media_time) {
> +gint32 time_diff =
> +compute_mm_time_diff(frame_op->multi_media_time,
> last_op->multi_media_time);
> +if (time_diff < 0) {
>  /* This should really not happen */
>  SPICE_DEBUG("new-frame-time < last-frame-time (%u < %u):"
>  " resetting stream, id %u",
> diff --git a/src/channel-display-priv.h b/src/channel-display-priv.h
> index b9c08a3..eced6af 100644
> --- 

[Spice-devel] [spice-gtk v2 1/2] Fix possible multimedia time overflow

[Frediano Ziglio]

The multimedia time can easily overflow as is encoded in an
unsigned 32 bit and have a unit of milliseconds so it wrap
up every 49 days. Use some math that allow the number to overflow
without issues.
This could caused the client to stop handling streaming and
starting only queueing.

Signed-off-by: Frediano Ziglio 
---
This patch should be applied independently on 2/2 as intended to be
merged upstream as a fix while 2/2 depends on this as it change same
code portions.
---
 src/channel-display-gst.c   | 11 ++-
 src/channel-display-mjpeg.c | 14 --
 src/channel-display-priv.h  | 19 +++
 3 files changed, 33 insertions(+), 11 deletions(-)

diff --git a/src/channel-display-gst.c b/src/channel-display-gst.c
index c4190b2..9c62e67 100644
--- a/src/channel-display-gst.c
+++ b/src/channel-display-gst.c
@@ -183,8 +183,9 @@ static void schedule_frame(SpiceGstDecoder *decoder)
 }
 
 SpiceStreamDataHeader *op = spice_msg_in_parsed(frame->msg);
-if (now < op->multi_media_time) {
-decoder->timer_id = g_timeout_add(op->multi_media_time - now,
+gint32 time_diff = compute_mm_time_diff(op->multi_media_time, now);
+if (time_diff >= 0) {
+decoder->timer_id = g_timeout_add(time_diff,
   display_frame, decoder);
 } else if (g_queue_get_length(decoder->display_queue) == 1) {
 /* Still attempt to display the least out of date frame so the
@@ -192,8 +193,8 @@ static void schedule_frame(SpiceGstDecoder *decoder)
  */
 decoder->timer_id = g_timeout_add(0, display_frame, decoder);
 } else {
-SPICE_DEBUG("%s: rendering too late by %u ms (ts: %u, mmtime: %u), 
dropping",
-__FUNCTION__, now - op->multi_media_time,
+SPICE_DEBUG("%s: rendering too late by %d ms (ts: %u, mmtime: %u), 
dropping",
+__FUNCTION__, -time_diff,
 op->multi_media_time, now);
 stream_dropped_frame_on_playback(decoder->base.stream);
 g_queue_pop_head(decoder->display_queue);
@@ -431,7 +432,7 @@ static gboolean spice_gst_decoder_queue_frame(VideoDecoder 
*video_decoder,
 }
 
 SpiceStreamDataHeader *frame_op = spice_msg_in_parsed(frame_msg);
-if (frame_op->multi_media_time < decoder->last_mm_time) {
+if (compute_mm_time_diff(frame_op->multi_media_time, 
decoder->last_mm_time) < 0) {
 SPICE_DEBUG("new-frame-time < last-frame-time (%u < %u):"
 " resetting stream, id %u",
 frame_op->multi_media_time,
diff --git a/src/channel-display-mjpeg.c b/src/channel-display-mjpeg.c
index 722494e..1b7373b 100644
--- a/src/channel-display-mjpeg.c
+++ b/src/channel-display-mjpeg.c
@@ -195,15 +195,15 @@ static void mjpeg_decoder_schedule(MJpegDecoder *decoder)
 do {
 if (frame_msg) {
 SpiceStreamDataHeader *op = spice_msg_in_parsed(frame_msg);
-if (time <= op->multi_media_time) {
-guint32 d = op->multi_media_time - time;
+gint32 time_diff = compute_mm_time_diff(op->multi_media_time, 
time);
+if (time_diff >= 0) {
 decoder->cur_frame_msg = frame_msg;
-decoder->timer_id = g_timeout_add(d, 
mjpeg_decoder_decode_frame, decoder);
+decoder->timer_id = g_timeout_add(time_diff, 
mjpeg_decoder_decode_frame, decoder);
 break;
 }
 
-SPICE_DEBUG("%s: rendering too late by %u ms (ts: %u, mmtime: %u), 
dropping ",
-__FUNCTION__, time - op->multi_media_time,
+SPICE_DEBUG("%s: rendering too late by %d ms (ts: %u, mmtime: %u), 
dropping ",
+__FUNCTION__, -time_diff,
 op->multi_media_time, time);
 stream_dropped_frame_on_playback(decoder->base.stream);
 spice_msg_in_unref(frame_msg);
@@ -249,7 +249,9 @@ static gboolean mjpeg_decoder_queue_frame(VideoDecoder 
*video_decoder,
 SpiceStreamDataHeader *last_op, *frame_op;
 last_op = spice_msg_in_parsed(last_msg);
 frame_op = spice_msg_in_parsed(frame_msg);
-if (frame_op->multi_media_time < last_op->multi_media_time) {
+gint32 time_diff =
+compute_mm_time_diff(frame_op->multi_media_time, 
last_op->multi_media_time);
+if (time_diff < 0) {
 /* This should really not happen */
 SPICE_DEBUG("new-frame-time < last-frame-time (%u < %u):"
 " resetting stream, id %u",
diff --git a/src/channel-display-priv.h b/src/channel-display-priv.h
index b9c08a3..eced6af 100644
--- a/src/channel-display-priv.h
+++ b/src/channel-display-priv.h
@@ -141,6 +141,25 @@ void stream_dropped_frame_on_playback(display_stream *st);
 void stream_display_frame(display_stream *st, SpiceMsgIn *frame_msg, uint32_t 
width, uint32_t