flash player a/v sync issue?

Issues related to playing with Flash Player

flash player a/v sync issue?

Postby benbiles » Tue Jul 06, 2010 8:27 pm

Hi, we are encoding / streaming x264 encoded h264 main 5.1 and mp3 audio with Unreal Liver Server to Unreal Media Server and playing stream
in Unreal Flash Player in Low latency mode.

We have Audio and Video sync drift after around 4 minuetes.

Has anyone else experienced this or have a work around?

Both encoder pc and decoder pc have enough cpu power., we have tried reducing bandwidth in case its a bandwidth issue and the same
sync issue.

We haev tried JWplayer but that plays at a slow frame rate? anyone else experienced that?

Was hopeing the audio and video would be locked together or interleaved? during encode? but alas I must be wrong.,

any ideas would be much appreciated,

perhaps AAC audio is better than mp3 in flash for Sync?

thanks,

BEN
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Re: flash player a/v sync issue?

Postby admin » Wed Jul 07, 2010 10:51 am

As another post suggests, you may have synch issues if your real frame rate is below 15 fps.
This is really a Flash bug; same happens if you encode with FME and stream with FMS.
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Re: flash player a/v sync issue?

Postby benbiles » Wed Jul 07, 2010 11:11 am

Hi, thanks for reply,

We are encoding / streaming at 25fps

if I use the unreal embeded player everything works, 24 - 26 fps

if I use the Unreal FLASH player I loose sync after a couple of minuetes

If I use the JW player, you can try yourself with the jwplayer setup wizard on JWplayer website
the stream plays at under 10 fps

Is it possible to get a 30 day trial using custom codecs? maybe aac audio would be better in flash ?

Thanks for your time answering this, ben
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Re: flash player a/v sync issue?

Postby admin » Wed Jul 07, 2010 10:35 pm

AAC wouldn't help.
Your video source must be providing strange timestamps....or your frame rate really drops after 2 minutes of play...
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Re: flash player a/v sync issue?

Postby benbiles » Thu Jul 08, 2010 3:58 pm

Hi, we are capturing with a Viewcast Osprey 240e card ( its the pci express version )

we are capyuring 25fps PAL 768x576 d1 standerd definition and cropping to 720 x 576 for flash compatabilty.,

The Osprey manual mentions an extra feuture for timestamp in the driver., could it be anything to do with this?
should we disable timestamp if it is 'on' ?

Also are there any requiremnents for the audio? we are capturing 44.1khz dual mono streams.,
should they be stereo interleaved? we noticed Unreal Live Server does'nt except 48khz source.
not that its a problem,

I found this in the manual,.

"" Timecode Video Marking: Refer to the Vertical Interval Timecode of this guide (Chapter 3, Page 60) for
more information.

Closed Caption Timestamping: This control is a workaround to what we currently believe to be a problem
in DirectShow with capture of CC to AVI files. If you attempt to capture a CC character pair stream along with a
video stream to an AVI file with “Normal” timestamping, the file will become extremely large and the capture will
fail within a few seconds. “AVI-Compatible” mode allows capture of CC to AVI. Unfortunately, the problems with
timestamping mean that time synchronization between the video and CC streams depends on their physical
interleaving in the file, so that time synchronization will be quite poor; we do not have a workaround for this at this
time. For all applications other than capture to AVI, this control should be set to “Normal.” WME9 among others
requires the “Normal” setting if CC is used. ""


We will test stereo paired audio in case that has any effect too.,

We have never experienced any slow down in frame rate on any other encoder software, we are running a 3 ghz quad with 4gig ddr3 ram with the osprey 240e

Will report back imedietely if we find a fix,

BEN
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Re: flash player a/v sync issue?

Postby benbiles » Thu Jul 08, 2010 5:32 pm

ok, I have tested this with a webcam also now.

I am getting a sync drift of 1 second after about 2 minuetes, and yes It could be becasue of
video frame rate slow down.

On the webcam i get just a slow down of video after two minuetes and then 1 second a/v drift that stays.,

On ofsprey i am getting violent audio pops and a random picture freeze that eventually causes 1 second a/v sync loss of 1 second.


i'll stick with webcam for now, I have tried ruducing key frames in x264 encoder to 1000 ms ( 1 second ? ) still the same

anything else I can try?
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Re: flash player a/v sync issue?

Postby benbiles » Mon Jul 12, 2010 12:39 pm

Is there a way to force the flash player keep audio / video in sync, even if cpu creeps over 75 percent momentarily causing slow frame rate?

Or is that a flash player limitation?

Would be great if we could fix this. The Unreal Player Plugin works so well but we dont want to ask our mac viewers to install direct show filters for quicktime,
etc etc

Ben
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Re: flash player a/v sync issue?

Postby admin » Mon Jul 12, 2010 9:55 pm

Looks like it's a problem of Flash player.
You have the same issue when streaming with FME->FMS.
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Re: flash player a/v sync issue?

Postby Muzolini » Sun Dec 05, 2010 8:48 am

I have a problem here,

I need to demo a live stream but the viewers are hesitant (on a good day) to download any players/pug ins .

Would be great if the synch problem was sorted .


Jeff
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Re: flash player a/v sync issue?

Postby admin » Tue Dec 07, 2010 5:14 pm

Th Media Server 7.5 improves audio-video synch in Flash player, even for low framerates.
However, nothing can really be done if the device provides incorrect timestamps. In this case you will get synch problems in any player.
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