• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

IEEE-1394 Firewire fancy trick question.


This is an old post of a guy named nlec from another forum...

is there any possibility nowdayz to connect a PC with a home DVD-recorder using Firewire port and transfering videos with one of the programs suggested in the following post?

Panasonic DVD recorders without hard disks do not play nice with others on the Firewire bus.

If you can get a DV stream on the bus the Panny will see it and you can record it. The Panny has the ability to reach out to other Firewire devices (camcorder or deck) and initiate a connection. The opposite is not true because the Panny does not respond to requests from the outside to establish a connection.

For most software you will find such as Enosoft DV Processor, Premiere Pro, Vegas, WinDV, MovieMaker, etc. what they do is query devices on the Firewire bus looking for units that report themselves as "tape subunits". Then they follow a communications protocol to set up a connection for control and the DV stream itself.

The Panny does not present any subunit on the bus, therefore software can't see it or talk to it.

In the PC world, Microsoft deserves a big share of the blame, too. There is a DV-over-firewire scenario called "broadcast" mode. In that mode, the DV stream goes out onto the bus without regard for any prior connections being set up. In theory, the DV gets broadcast on the bus and any listener node that's interested can receive the stream.

The Panny sees such a stream and will record it from its "DV In" port. Unfortunately, Microsoft in their infinite wisdom chose to neuter broadcast mode in their drivers for XP. It is impossible to set up a broadcast DV stream on Windows without some very fancy trickery.

There is further blame to be shared by the manufacturers of IEEE 1394 adapters and the film industry. Early Firewire cards had a "snoop" mode similar to the "promiscuous" mode of network adapters. Hollywood put pressure on the manufacturers of IEEE 1394 Firewire adapters to remove "snoop" mode from their hardware. The new spec is called OHCI and it does not have a "snoop" mode. All new Firewire cards follow this spec.

If you could snoop the bus it would be possible to capture the communication between the Panasonic recorder and a camcorder to see what was going on. That conversation could be reverse-engineered and, in theory, you could write drivers and/or software to emulate a camcorder that would run on your PC. The Panny would think it was talking to a camcorder.

Latest threads

EE World Online Articles