New World Symphony

 

DVTS Working notes

 

Digitized Video Transport System is a software application for streaming DV25 video over IP developed by the WIDE project in Japan. It works on a number of OS’s but New World Symphony prefers the Windows XP implementation because of it’s superior GUI, reliability, and the host of free testing and system monitoring apps available on Windows. The notes below apply to Windows XP unless otherwise noted.

 

NWS is currently using development builds 0.0.1 and 0.0.2. There is also an HDV version available that bundles 0.0.2 with the HDV version.

 

 

Bugs

·         A major bug occurs on the first initialization of receive after the program is opened. On most XP machines, your CPU usage will stay at 100% (50% on dual core). This will cause packet loss in the program (not network related) and increased latency, even though the incoming network traffic does not appear problematic. Always press receive twice after you’ve opened the app.

·         A less critical bug involves multicast time-to-live. TTL’s of 100 and above do not recognize the one’s digit. For example, a TTL of 100 is actually 10; TTL 128 is actually 12; so the highest TTL possible is 99. I’ve never seen a route beyond 30 hops even over commodity internet, so TTL’s of 25 or less should accommodate the national Internet2 network and most international peers.

·         See last latency point below.

 

 

Tech specs

 

IP Protocol:

UDP

Port:

8000 (default), or any of your choosing

Datagram length:

1400 bytes (default)

Datagrams/sec:

2670 (default)

Throughput:

~29 Mbps

I/O

Your PC’s 1394 firewire port and NIC

For DV25 audio/video specs please see The DV FAQ

 

 

Other Notables

 

·            Input is via DV over firewire only (either directly from a DV camera, DV converter, or VTR)

·            Output is via software on screen display or via hardware firewire out of the PC. It is not recommended that you use both simultaneously; I’ve not yet found a PC that can handle this.

·            You should continuously monitor IP throughput in Task Manager when running DVTS. Most of this “Are you sending, are you receiving???” business is not necessary if you are monitoring what is actually going in and out of your system.

 

 

Latency

 

·            DVTS latency is mostly a factor of buffering on the receive side. Software receive latency is estimated at <300 ms, though I haven’t checked definitively. It is on par with H.323 videoconferencing, but greater than Star Valley Solutions’ SVS-2000 MPEG2 units.

·            The hardware firewire out has greater latency than viewing the software on screen display.

·            The Comet PCI card hardware has about the same latency as DVTS software receive.

·            Any other CPU usage will interrupt the onscreen display and increase latency. Do not open apps while DVTS is running. Restarting receive will bring the latency back to nominal.