[Spice-devel] [PATCH spice-server 00/28] adaptive video streaming
Yonit Halperin
yhalperi at redhat.com
Wed Apr 17 07:50:25 PDT 2013
On 04/17/2013 10:47 AM, Alon Levy wrote:
> On Mon, 2013-04-15 at 14:54 -0400, Yonit Halperin wrote:
>> Hi,
>> On 04/14/2013 09:37 AM, Alon Levy wrote:
>>> On Tue, Feb 26, 2013 at 01:03:46PM -0500, Yonit Halperin wrote:
>>>
>>> ACK series, sorry for the delay. I have to admit I don't understand the
>>> first patches as well as I should, but seeing as they have been tested
>>> and that I would just be delaying them further, I prefer to let you push
>>> them. I hope to work a bit on testability of streams that doesn't
>>> require creating a vm, but of course that too is just a note and not
>>> related to acking this series.
>>>
>> Thanks for reviewing.
>> Anyone care to also review the spice-gtk,spice-common and spice-protocol
>> patches?
>
> I think it's best I review those too.
>
Cool, Thanks.
>>
>> Thanks,
>> Yonit.
>>
>>>> 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.
>>>>
>>>> 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
>>
>
>
More information about the Spice-devel
mailing list