[AG-TECH] AG hardware improvements and HD content sharing

[Christoph Willing]

On 12/02/2007, at 9:33 AM, gskpop wrote:

> Christoph Willing wrote:
>> Compressed HDV directly from cameras has a latency of about half a  
>> second. That is acceptable for non-interactive sessions (and  
>> perhaps _some_ interactive sessions).
> Chris, is this true of all HDV cameras? I thought it was higher. Is  
> it true for the Sony HC-7 that sells for about $1400?  I was
> trying one out but got different latencies--probably depends on the  
> application involved.


Gurcharan,

Perhaps half a second latency for HDV is a bit optimistic. There are  
multiple factors involved. The initial problem is the time taken (in  
the camera) to generate the MPEG2 HDV stream. A stream with a GOP of  
12 implies a minimum half second latency (for PAL). After that, the  
grabbing/transmitting software, network performance and receiving/ 
renderering software will all have some impact on the end to end  
latency.

Our test cameras are the Sony HVRZ1 and HDRHC3 models which are  
switchable between DV and HDV. We also been using Canopus ADVC110 and  
ADVC55 to generate ordinary DV from composite cameras.


> I was using it with ExtendedVideoService  module that Sang Woo Han/ 
> GIST is working on for the WindowsXP platforn.
>> We have recently developed a new version of vic with DV and HDV  
>> capture & display capability. The Linux version is working well  
>> and the Windows port is just about to begin.
> Can I get hold of the linux version to start playing with it? I am  
> installing some public "portals" on campus that will
> be always on, persistent video/audio for "one on one" ad hoc  
> communication and want to use the best quality video I can. I may  
> have to start with DVTS but pending funding I'd like to move to HDV  
> and eventually to uncompressed HD.


There are some binaries at:
	http://www.vislab.uq.edu.au/research/accessgrid/software/advideo/ 
status.html


The AG service wrappers there partially work. For proper operation,  
they depend on some AG toolkit changes which are expected for the  
AG3.1 release.


The source code will be available in a day or so from an SVN  
repository we're setting up right now.


chris



>> Uncompressed HDV would be ideal, but the bandwidth required is  
>> around 1 Gb/s - not a realistic proposition for most networks.  
>> Bandwidth of the compressed streams is around 30Mb/s, so you can  
>> have multiple HDV streams on a good network (if you can tolerate  
>> the latency). Also, the HD YUV capture cards cost thousands of  
>> dollars.
>>
>>
>> chris


Christoph Willing                       +61 7 3365 8350
QCIF Access Grid Manager
University of Queensland