Hi Ruben,

Thanks for the info, your approach sounds reasonable to me.

I am still unclear on what hardware setup you are using. I found this page - http://wiki.teltek.es/display/Galicaster/Hardware+recommendations - so I am guessing you are probably running your captures against an Intel i3 processor with some sort of Hauppauge card.

So in summary:

a) using the above hardware setup, you had some video sync/dropped frame rate issues b) these issues were fixed with "a different pipeline structure with the element 'videorate' to guarantee the video stream synchronization"

In theory, adding "videorate" to the MH capture agent pipeline should also fix this issue, but the placement of this element is probably key to the whole thing!

Let me know if I got any of the above wrong.

  Kevin Chan

  Operations Team
  Educational Technology Services
  UC Berkeley


On 2/6/12 4:51 AM, Rubén Pérez wrote:
Hi all,

The pipeline we are using in Galicaster is rather different than the one used in the standard capture agent in many ways, the first one coming to my mind being the fact that Galicaster needs to provide video feedback and the CA doesn't.

Still, I will take a look and see if we can commit some changes to improve the synchronization quality. I cannot guarantee though.

The pipeline used is in the code of Galicaster, available at www.galicaster.org <http://www.galicaster.org> .

Sorry I cannot be more specific right now. When I have some spare time I'll try to document myself on this topic and try to apply a patch based on our research in Galicaster, if that's feasible without altering the current CA pipeline too much. Does this sound reasonable?

Regards

2012/2/2 Kevin Chan <[email protected] <mailto:[email protected]>>

    Hi Ruben,

    Was this "fix" done against the referenced MH capture hardware or
    some other hardware setup?

    In any case, thanks for the info, it would be great if you can
    provide this info for the MH developers in:
    http://opencast.jira.com/browse/MH-8505

    Also, if you can provide the full pipeline structure, that would
    be great (for novice pipeline constructors like me).

       Kevin Chan

       Operations Team
       Educational Technology Services
       UC Berkeley


    On 1/30/12 5:38 AM, Tobias Wunden wrote:
    Hi Ruben,

    any chance that fix will make it back into trunk anytime soon? It
    would have been great to have this in for 1.3 as well, given that
    you seem to have sorted out that issue a while ago.

    Tobias

    On 30.01.2012, at 09:15, Rubén Pérez <[email protected]
    <mailto:[email protected]>> wrote:

    Hi Kevin,

    I can also confirm that we experienced the same frame drop/out
    of sync problem in long recordings, both in the capture agent
    and also in Galicaster's development stages. Finally, we
    discovered that the key was a different pipeline structure with
    the element 'videorate' to guarantee the video stream
    synchronization.

    Maybe you could try and add this element to the CA's standard
    pipeline, and see what happens. Of course, you can also try
    Galicaster :)

    Good luck
    Rubén

    On 25 Xan, 2012 07:18, "Kevin Chan" <[email protected]
    <mailto:[email protected]>> wrote:

        Hi all,

        During preliminary testing of a 2h 15m capture (which we
        intend to post produce for YouTube), UC Berkeley discovered
        that the capture files for video and screen were off by 15m
        (with the screen capture via Epiphan being 15m short), which
        is more or less unacceptable to our post production folks
        (as it is very difficult for them to stitch this back
        together). This is likely to be due to dropped frame rate,
        but it is a bit difficult to confirm.

        I am wondering if anyone else (besides Saskatchewan folks,
        who confirmed this issue) has encounter this issue and how
        they are working around it. I imagine that lowering
        framerates and bitrates would work, though some initial
        testing using various capture agent configurations seems to
        suggest that the capture files are still off by a few
        minutes even with the CPUs being not fully taxed.

        We are using the reference capture agent hardware and very
        basic capture agent settings. This issue has been filed in
        MH Jira if anyone is interested:
        http://opencast.jira.com/browse/MH-8505

        Finally, we have heard that there are various hardware and
        configuration setups for Matterhorn Capture Agents in
        production. I think it would be great if that we, as a
        community, can share this information (via the MH wiki) to
        help each other understand and learn about the various use
        cases and setups that are employed.

        Thanks,

-- Kevin Chan

           Operations Team
           Educational Technology Services
           UC Berkeley


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