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New Member

IP/TV & VBrick

Having problems with recordings made with a VBrick and then played by IP/TV. Dropping frames excessively, voice/video out of synch. Anybody have any input?

6 REPLIES
New Member

Re: IP/TV & VBrick

Some thoughts -

1.) Check the source file and play with WMT from a local file to make sure that the file itself does not contain the distortions you mention.

2.) Check the viewer host PC to make sure the CPU can handle the decode requirements. IPTV uses s/w decode for the most part so the CPU is taxed. If your source file is MPEG1/2 at high b/w (i.e. >1.5MB/s) and your PC has a slower CPU, this could be the issue.

3.) When streaming the file from IPTV server, select the program played to look at its source play statistics to see if the program is being streamed at the proper rate.

4.) Finally, check your network. Is QoS necessary in your environment? If so, what has been implemented?

New Member

Re: IP/TV & VBrick

I've been troubleshooting this for a bit so I've tried 1-3 already and everything looks good. How do I know if I need QoS? How do implement it?

New Member

Re: IP/TV & VBrick

Unfortunately, this question is impossible to answer in any meaningful manner on a BB. I suggest contacting your local Cisco rep/SE to look at the specifics of your network then make recommendations.

New Member

Re: IP/TV & VBrick

It sounds like the questions have been answered and the initial issues resolved, but I thought I would offer a few comments on QoS.

First, QoS is a non-issue at the Ethernet workgroup switch level if the sum of the ports is equal to or greater than the capacity of the switch backplane. In other words, Ethernet switches that cannot be oversubscribed. QoS is really only an issue on bandwidth constrained or oversubscribed pipes, which may be the case outside of a workgoup. As SACHON says, impossible to deal with in a BB and best to consider the QoS needs of the whole network.

To the extent that the video is live, the VBrick itself offers DiffServ capabilities where you can set the TOS field. This allows upstream routers to prioritize the live traffic over non-realtime traffic such as http and email.

While true QoS is of course a complicated subject, one can avoid having to "go there" through the appropriate use of multicasting (which has the effect of reducing the need for bandwidth and hence helps to make real QoS less of an issue).

New Member

Re: IP/TV & VBrick

Another possible solution is to make the recording using IPTV instead of the VBrick software. I have recorded live VBrick streams and replayed them using IPTV successfully with this method.

New Member

Re: IP/TV & VBrick

OH, wait ... I just remembered something. I had the same problems you reported (audio/video out of sync, dropped frames) using the VBrick and IPTV viewer at any speed other than 1Mbps. You have to set the VBrick to stream at 1Mbps. Crazy, I know ... but that's how I got it to work with IPTV.

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