[PLUG-AV] Fwd: Re: Dumping to screen gets slower, and slower

[James Bromberger]

Response from Ben (dvswitch-devel), FYI.

-------- Original Message --------
Subject: 	Re: Dumping to screen gets slower, and slower
Date: 	Thu, 15 Sep 2011 04:46:11 +0100
From: 	Ben Hutchings <ben at decadent.org.uk>
Reply-To: 	dvswitch development discussions
<dvswitch-devel at lists.alioth.debian.org>
To: 	dvswitch-devel at lists.alioth.debian.org



On Thu, 2011-09-15 at 11:17 +0800, James Bromberger wrote:
> Hello all,
> 
> 
> I was using dvsink-command -h $host -p $port -- mplayer - the other
> night during a PLUG presentation (www.plug.org.au) in order to show
> the video stream to the room we were recording in. It started off that
> the delay between what we were mixing on dvswitch and what we were
> seeing from this dvsink command was around .2 of a second. As the hour
> progressed, this became further and further lagged, to a few seconds.
> 
> Anyone got any better solutions or fixes for this? Would it be the
> speed of the host showing the video that could be an issue. or do
> others see this.  Is mplayer recommended over VLC (or something else)
> to render the video?

I've not seen this, but I think it could happen if the audio clock runs
slow on the playback machine (say, 47.9 kHz when it should be 48 kHz) or
fast on the audio source, or both.  If you disabled audio playback
completely then it could happen if the system clock runs slow on the
playback machine.

> If I have a video file (with audio) and I want to route the audio out
> to a mixing desk and send the video to the dvswitch app - would you
> recommend a gstreamer command line or something else?

Sorry, I haven't done much with gstreamer yet.

Note that by default dvsource-alsa delays audio by 0.2 seconds to match
the typical processing delay in a video camera.  In this case there
wouldn't be any such processing delay for the video, so you would need
to override the audio delay to keep them in synch.

> When playing out a dvsource-file, is it feasible to get a verbose
> option to tell you how many seconds through and how many seconds
> remain on a file being sent to the dvswitch console?

No, it's not.  It probably wouldn't be that hard for you to add.

> That way, when plaing an into video, I can see when I have 1 second
> left of intro and can then switch to the live camera(s) before the
> file ends (and in combination with audio routing above, can have intro
> music keep being heard as I bring in room audio and room video).
> Alternatively, is this meta data available to overlay (or beside) a
> video source window in DVswitch?

The network protocol doesn't provide any such metadata.

> When a source disconnects, can we remove the slot it occupies in the
> gallery? 

Currently, no, it's assumed that you'll try to reconnect the source.  I
realise this assumption is wrong when you use a non-looping file source!

Ben.

-- 
Ben Hutchings
All extremists should be taken out and shot.


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