Apple claims the video capture on the imac dv has, i quote "zero loss of quality" . is this true, and if so, how is it done?

-- ndumu (ndumu@hotmail.com), October 19, 1999

Answers

The iMac DV has 2 firewire connections (IEEE 1394 standard, or iLink on Sony Digital camcorder). The download is truly zero loss since it download an exact copy of the digital data. Forewire does not digitize analog video. Kiam Oey

-- Kiam Oey (kiam.t.oey@boeing.com), October 20, 1999.

Yes Kiam!

Digital video is based on a 5:1 compression and therefore there is a loss at the taking stage but after that no loss occurs using firewire digital transfers.

All this is a bit like mpeg-2 MP@ML having a capability of 15Mbits/second but the dvd spec requirement for a maximum bitrate of only 9.8 Mbits/sec may induce comment. The point of diminishing returns (no visual difference between original video and compressed video) is widely known to be around 9 Mbits/sec.

The equivalent in dv is apparently judged to be a compression of 5:1 or a data transfer rate of about 3.7M/s and somewhat higher in analogue.

-- Ross McL (rmclennan@esc.net.au), October 20, 1999.

are u saying the imac dv has built in mpeg2 capture?

-- ndumu (ndumu@hotmail.com), October 20, 1999.

No not at all, all I was pointing out is, like Kiam said, dv -> dv firewire transfers are lossless and that at the imaging stage there are losses and there is a point where any loss is not noticed in the viewing process. I have transcribed mini-DV from a TRV 900 camera to D8 and vica versa without any noticable loss, its digital.

The other point is that some might say there is "zero loss" in DVD. The specification for DVD only uses 65% of the capability of its MPEG- 2 base, you do not see, with current consumer TV's, the higher quality even if you use it.

-- Ross McL (rmclennan@esc.net.au), October 21, 1999.