[vlc] Re: How to do a live stream with minimum latency?

[Mark Moriarty]

What I've seen, doing long-range CCTV surveillance, is about 160 ms end-end
latency using dedicated T1 and MJPEG HW (not video over IP).

Last year I experimented with a commercial wavelet CODEC, video over IP,
640x480, was actually generally in the < 120 ms zone.  My test sequence was
a video of a catamaran race, superimposed 0.01 sec resolution timestamp,
latency measured by photographing monitors side-by-side (one monitor was the
TX stream, which went from the monitor port through a VGA/NTSC converter,
then into a framegrabber with the SW CODEC processing the grabbed data; the
other monitor depicted RX CODEC display, SW processed video over IP with the
two PCs connected using an Ethernet crossover cable.  Since the underlying
video stream was 30 fps, my latency "LSB" was 33 ms).  A real screamer in
terms of processing speed.  Unfortunately the vendor had targetted a niche
that didn't cover my application, so wasn't willing to do tuning that I
needed.  C'est la vie!

Based on the wavelet experience, however, I am firmly convinced that sub-200
ms performance should be achieveable, at high resolution, full 30 fps, in
streamed video-over-IP.  

-----Original Message-----
From: vlc-bounce at videolan.org [mailto:vlc-bounce at videolan.org] On Behalf Of
Alexander Isacson
Sent: Friday, May 14, 2004 4:59 PM
To: vlc at videolan.org
Subject: [vlc] Re: How to do a live stream with minimum latency?

I haven't tried hardware encoders but I'm very curious about any results you
get. Please let me know. My guess would be that you won't be able to go
lower then 500ms, but that's just of the top of my head. The BT878 has about
500ms latency just showing the stream on a local screen (from what I hear).

I would also like to know what the latency is from a network camera
streaming motion JPEG or similar.
 
--
Alexander Isacson <alexander at isacson.info>

On Fri, 2004-05-14 at 18:52 +0200, Marco De Benedetto wrote:
> On ven 14 mag, Alexander Isacson wrote:
> > Hello
> > 
> > You can bring it down a bit, ~1 sec, by minimizing the UDP-cache and 
> > V4L-cache. Look at those command line options.
> 
> Thank you, latency is now actually ~1 sec.
> 
> Do you know if latency can be lowered with hardware mpeg encoders?
> 
> --
> Marco De Benedetto
> 
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