fms 3.5.2 - video/audio streaming application - audio stops or lags behind

[Outreach I.T.]

Yesterday, I ran a simple live video streaming application for the first time with actual users and ran into a couple of serious performance issues that had not turned up during testing.

In this instance there was one video stream from a live web cam and used FMLE at 150 kbps using VP6 and MP3 @22k.

There were 16 clients and everything worked pretty good for about 30 minutes.  (although some clients said their audio and video were out of sync by up to 3 seconds)

Then individual clients would have either the video freeze or the video would continue and the audio would stop.  These clints had to "disconnect" and then "connect" again to the application.  This happened to all of the clients at one time or another for several minutes.

I stopped and restarted the FMLE with progessively lower bandwidth settings down to 75 kbps but still clients were having the same issue.

I eventually stopped the FMLE and used the applications built in publisher at 45 kbps and that seemed to eliminate the freeze/dropping issue.

But of course the video quality was very poor and some clients still reported that the audio was out of sync with the video.

The server hosting the FMS application is a quad processor dell with lots of memory and network connectivity.

The Flash Media Admin Console performance graph showed the total Bandwidth as 3 Mbps at maximum.

Any thoughts on what might have gone wrong?

Phil

[Outreach I.T.]

Perhaps some further information might spur some replies.

I started with a fresh application folder and customized the ASC, and application.XML.

The stream that is having the audio lag / video freeze issue is created by a server side function that creates a new STREAM and attaches a published stream from a client or FMLE to the applicaiton.

In testing the application with up to 4 clients I have had no problem with connectivity, audio lag or video freeze ups even if I ran the application for several hours.

So, I guess my main question is how does this symptom relate to the number of clients?

[Outreach I.T.]

Since, I see other people viewing this I will update the status.

I am still having trouble with audio and video lagging up to 5 to 10 seconds from the live feed and jerky video quality.

BUT by changing the Application.XML so that the Process>Distribute>numprocs equals "1" instead of the default of "3" seems to make the delay time more consistant between clients.

At this point I would have to say that FMS is great for VOD applications but not so good for LIVE interactive apps?

[rexdtripod]

I'd have to concur at this point.  Doing the same thing here.  FMLE 3.0 streaming to FMS 3.5, good machines, and a  T1 between them.  With just one client (me) audio is lagging behind video by anywhere from 5 seconds using VP6 to 20-30 seconds with H.264.  I'm not sure if I'm missing something really obvious or if this is actually how it performs.  Have to do more digging.

[Guest]

Have you tried combining audio samples?

http://help.adobe.com/en_US/FlashMediaServer/3.5_AdminGuide/WS5b3ccc516d4fbf351e63e3d119f2925e64-7ff0.html#WS5b3ccc516d4fbf351e63e3d119f2925e64-7fea

Jody

[Outreach I.T.]

The simple answer is no.

I had read that part of the documentation that you referenced but really didn't understand whether we should or shouldn't be changing those settings.

Any suggestions on setting values to try?

[rexdtripod]

Hmm...  A little more testing here has shed a little more light.

Seems to be a web cam/FMLE FPS conflict of some sort.  I'm not real well versed in web cams and their inner workings but here's what I've noted:

My Creative web cam and FMLE set to encode at 15 FPS and audio and video are way out of sync.  FMLE at 10 or 20 FPS though and audio and video sync perfectly.  Just doesn't like 15 FPS.

Switch to a Logitec cam and the numbers change - 20 FPS way out of sync, but 10 and 15 perfectly in sync.  Must be something about the math involved in the various configurations.

Again, I know nothing about web cams so will have to look into it further.  Just figured I'd report what I'm getting here.

[ariestav]

Hi There,

Not sure if this helps or not, but I had a similar problem whereby my microphone data was being recorded (streamed) to the server and after downloading the created file to my desktop, and playing the .flv in a MacOSX media player (specifically VLC player), the audio was very slow--sounded like the voice was very low-pitched.  I couldn't find a solution to my problem, and then I stumbled upon this thread in my hunt for an answer.

The finding that it could be a webcam issue intrigued me, so I went back to my code in the Flash client I wrote to record the mic audio.  I simply specified the rate that the mic should capture at in my code, and the audio played back just fine.  Here is my code that defines the microphone object:

private function addMedia ():void
          {
               mic=Microphone.getMicrophone();
               mic.rate = 22;
          }

Specifying the .rate property was key in making sure the audio would both record and playback normally for me.  In the Flash documentation, there are specs regarding the .rate property:

rate    property    
rate:int  [read-write]
Language Version :     ActionScript 3.0
Player Version :     Flash Player 9

The rate at which the microphone captures sound, in kHz. The allowed values are any of the following your sound device supports: 5, 8, 11, 22, or 44.

The default value is 8 kHz if your sound capture device supports this value. Otherwise, the default value is the next available capture level above 8 kHz that your sound capture device supports, usually 11 kHz.

Hope that may help you.  If not, maybe it will help another person with a similar problem.

Thanks for starting this thread!

[calmchessplayer]

Thanks ariestav I was having the auido lag problem and didn't even know it untill i read this thread set my rate to 22 and everything is fine now.......Thanks for helping me to better understand what the rate setting can be used for. Kudos to the thread starter too.