[Spice-devel] [PATCH spice-server 00/28] adaptive video streaming
Andrew Cathrow
acathrow at redhat.com
Thu Mar 7 12:57:16 PST 2013
----- Original Message -----
> From: "Yonit Halperin" <yhalperi at redhat.com>
> To: "Andrew Cathrow" <acathrow at redhat.com>
> Cc: spice-devel at freedesktop.org
> Sent: Thursday, March 7, 2013 3:52:04 PM
> Subject: Re: [Spice-devel] [PATCH spice-server 00/28] adaptive video streaming
>
> Hi,
> On 03/03/2013 07:50 AM, Andrew Cathrow wrote:
> >
> >
> > ----- Original Message -----
> >> From: "Yonit Halperin" <yhalperi at redhat.com>
> >> To: spice-devel at freedesktop.org
> >> Sent: Tuesday, February 26, 2013 1:03:46 PM
> >> Subject: [Spice-devel] [PATCH spice-server 00/28] adaptive video
> >> streaming
> >>
> >> Hi,
> >>
> >> The following patch series introduces adaptive video streaming to
> >> spice.
> >>
> >> Until now, the mjpeg quality was constant (70), and the frame rate
> >> was modified
> >> according to the rate of frame drops in the server side (a drop
> >> occurs when a new frame reaches the server while
> >> an older frame is still queued in the pipe). In the client side,
> >> the
> >> video playback is synchronized according
> >> to the audio playback (each audio and video frame holds an mm-time
> >> field). The jitter-buffer size in the client
> >> was constant as well - 100 ms. When video frames arrive late to
> >> the
> >> client (i.e., when the audio playback is ahead of them),
> >> they are dropped.
> >>
> >> The adaptive video streaming is implemented by the following
> >> heuristic:
> >> Given a bit rate, we calculate the best combination of mjpeg
> >> quality
> >> and frame rate (henceforth, the stream parameters) for this
> >> bit rate. In order to decide this combination, we evaluate the
> >> encoding size for different jpeg
> >> qualities by applying them on successive frames.
> >> Every new stream is assigned with an initial bit rate. The bit
> >> rate
> >> is re-estimated and
> >> modified during the stream life time. The bit-rate is modified
> >> based
> >> on:
> >> 1) periodic reports from the client:
> >> The client reports includes information about drops and the
> >> playback latency.
> >> In response to drops, or too short playback latency, we
> >> decrease
> >> the bit rate.
> >> In response to reports that suggest that the client playback
> >> is
> >> stable with the
> >> current configuration, we try to increase the bit-rate.
> >> 2) server drops: the bit-rate is decreased when server drops
> >> occur.
> >>
> >> Each time the bit rate changes, the stream parameters are
> >> re-evaluated.
> >> In addition, we monitor the frames' encoding size, and when there
> >> is
> >> a change
> >> that may allow improving the stream parameters, or alternatively,
> >> requires decreasing the
> >> quality, we again re-evaluate them.
> >
> >
> > What kind of metrics do we expose - how can I get the bitrate back
> > on the client and/or server?
> >
> The server side estimates the latency, and an optimal bit rate for
> the
> video playback, which is dynamically modified throughout the
> playback.
> This measurements are kept on the server (they are documented in the
> log
> file if you run with the highest debug level).
I think we should consider exposing these through at least through qemu monitor/libvirt on the host side but also what we want to expose into the client through the guest agent.
> >>
> >> Other changes:
> >> --------------
> >>
> >> Besides the client reports, I also added to the protocol a message
> >> that controls the
> >> audio playback latency, for allowing better synchronization of the
> >> audio and video playback buffering.
> >>
> >> The roundtrip time is used for estimating the required playback
> >> delay. In order to get a more accurate estimation
> >> of the roundtrip time I also added an option to measure it
> >> periodically instead of just on startup, and
> >> take the minimum measurement as estimation.
> >>
> >> Results
> >> -------
> >> I compared the video quality of the current spice master, and of
> >> the
> >> new spice, under different network setups.
> >> Spice master was a bit modified for making the comparison more
> >> fair:
> >> I increased the audio jitter buffer to 200ms (instead of 100),
> >> and also included the patch "red_worker: stream agent - fix
> >> miscounting of frames".
> >> The network setup was emulated using tc.
> >>
> >> You can find the tests details and the results in a following
> >> email.
> >>
> >> For 5Mpbs and 60ms roundtrip (Test1), in spice-master, more than
> >> 70%
> >> of the frames that are sent to the client are being dropped, and
> >> the
> >> video
> >> is unwatchable. With new spice, while the average frame rate is
> >> about
> >> the same, only about 2% of the frames are being dropped by the
> >> client.
> >> For 2.5Mbps and 60ms (Test2), as expected, things gets worse for
> >> spice-master, and the drops rate reaches 90%. For the new spice,
> >> it
> >> is less then 20%, and
> >> the video is watchable.
> >>
> >> I also tested a setup of 10Mbps with high latency (170ms, Test3).
> >> The
> >> latency affects the initial bit rate estimation in spice (probably
> >> due to the tcp acks overhead).
> >> Thus, the stream is started with a bit-rate estimation of less
> >> then
> >> 1.25Mbps. The adaptive video heuristic gradually converges to a
> >> higher bit rate (the column "end-bit-rate"), and
> >> the next video stream will be started with the improved bit rate
> >> estimation.
> >> In Test5 I tested a real environment with a network setup similar
> >> to
> >> Test3. However, the test are not comparable because in Test5 setup
> >> (different server and guest),
> >> the basic frame rate (i.e., from the guest to the server) is much
> >> smaller (still need to investigate why).
> >>
> >> In Test4 (20Mbps; <1 ms roundtrip), I evaluated and unlimited
> >> setup,
> >> i.e., a setup which will allow the best frame rate and
> >> jpeg-quality
> >> for the stream.
> >> With new spice, the capacity of the channel is exploited
> >> efficiently.
> >> With spice-master, the condition for dropping frames according to
> >> the defined fps is too strict,
> >> and the observed frame rate is smaller then the maximum possible.
> >>
> >> Video streaming short-term TODO:
> >> ----------------
> >> - Implement playback-latency adjustments for spice-gtk gstreamer
> >> front-end.
> >> - Add vp8 encoding
> >> - Solve some problems we have with video identification.
> >> - Try to achieve faster convergence to the "right" bit-rate when
> >> we
> >> start with a wrong estimation.
> >>
> >> long-term TODO:
> >> ---------------
> >> video pass-through
> >>
> >> Regards,
> >> Yonit.
> >>
> >> Yonit Halperin (28):
> >> red_worker: stream agent - fix miscounting of frames
> >> server/red_worker: streams: moving mjpeg_encoder from Stream to
> >> StreamAgent
> >> mjpeg_encoder: configure mjpeg quality and frame rate according
> >> to
> >> a
> >> given bit rate
> >> mjpeg_encoder: re-configure stream parameters when the frame's
> >> encoding size changes
> >> mjpeg_encoder: adjust the stream bit rate based on periodic
> >> client
> >> feedback
> >> mjpeg_encoder: modify stream bit rate based on server side pipe
> >> congestion
> >> mjpeg_encoder: update the client with estimations for the
> >> required
> >> playback latency
> >> mjpeg_encoder: move the control over frame drops to
> >> mjpeg_encoder
> >> mjpeg_encoder: keep the average observed fps similar to the
> >> defined
> >> fps
> >> mjpeg_encoder: add stream warmup time, in which we avoid server
> >> and
> >> client drops
> >> server: spice_timer_queue
> >> server/red_worker: assign timer callbacks to worker_core, using
> >> spice_timer_queue
> >> red_channel: monitor connection latency using MSG_PING
> >> red_worker: stream - update periodically the input frame rate
> >> server/red_worker: enable latency monitoring in the display
> >> channel
> >> red_worker: start using mjpeg_encoder rate control capabilities
> >> red_worker: support SPICE_MSGC_DISPLAY_STREAM_REPORT
> >> red_worker: notify mjpeg_encoder on server frame drops
> >> red_worker: ignoring video frame drops that are not due to pipe
> >> congestion
> >> dispatcher.h: fix - s/#define MAIN_DISPATCHER_H/#define
> >> DISPATCHER_H
> >> snd_worker: support sending SPICE_MSG_PLAYBACK_LATENCY
> >> reds: support mm_time latency adjustments
> >> red_worker: video streams - adjust client playback latency
> >> server/red_worker.c: use the bit rate of old streams as a start
> >> point
> >> for new streams
> >> server/red_worker: add an option to supply the bandwidth via
> >> env
> >> var
> >> collect and print video stream statistics
> >> red_worker: increase the interval limit for stream frames
> >> red_worker: assign mm_time to vga frames
> >>
> >> server/Makefile.am | 2 +
> >> server/dispatcher.h | 6 +-
> >> server/inputs_channel.c | 1 +
> >> server/main_channel.c | 7 +-
> >> server/main_channel.h | 1 +
> >> server/main_dispatcher.c | 32 ++
> >> server/main_dispatcher.h | 2 +
> >> server/mjpeg_encoder.c | 981
> >> ++++++++++++++++++++++++++++++++++++++++++++-
> >> server/mjpeg_encoder.h | 70 +++-
> >> server/red_channel.c | 228 +++++++++++
> >> server/red_channel.h | 18 +
> >> server/red_dispatcher.c | 1 +
> >> server/red_worker.c | 514 +++++++++++++++++++-----
> >> server/reds-private.h | 2 +
> >> server/reds.c | 28 +-
> >> server/reds.h | 2 +
> >> server/smartcard.c | 1 +
> >> server/snd_worker.c | 45 +++
> >> server/snd_worker.h | 2 +
> >> server/spice_timer_queue.c | 268 +++++++++++++
> >> server/spice_timer_queue.h | 43 ++
> >> server/spicevmc.c | 1 +
> >> spice-common | 2 +-
> >> 23 files changed, 2148 insertions(+), 109 deletions(-)
> >> create mode 100644 server/spice_timer_queue.c
> >> create mode 100644 server/spice_timer_queue.h
> >>
> >> --
> >> 1.8.1
> >>
> >> _______________________________________________
> >> Spice-devel mailing list
> >> Spice-devel at lists.freedesktop.org
> >> http://lists.freedesktop.org/mailman/listinfo/spice-devel
> >>
>
>
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