Firewire bandwidth
by Kai Nagel
on
Jul 22, 2009 at 9:56:58 pm
Hi,
I've a question about the V4HD bandwidth usage. The Firewire port offers a maximum of 800 MBit/s. If I calculated right a 10Bit 1080i30 video needs a bitrate of about 1250 MBit/s. We'll have to add the audio datarate to this value.
It is obvious that the V4HD uses some sort of compression before sending the data over the bus. Prores doesn't seem to be supported in hardware. So does anyone have an idea what is going over the Firewire bus? How hard is the compression?
One possibility would be, that everything is converted to DVCProHD, sent over the bus and then converted to Prores on the Mac. But we would loose the full raster then.
Re: Firewire bandwidth by Nils Abel on Jul 24, 2009 at 1:01:08 pm
Hi Nagel,
I'm not sure what kind of codec the V4HD is using to get the full raster video through Firewire, but you can be sure that the V4HD is not using normal DVCProHD for full raster video. You are right that Prores is not compressed in the hardware but, in full raster mode, the V4HD delivers a 1920x1080 stream that is similar to ProRes. There is no quality disadvantage to ProRes. It's a kind of basis codec.
