[MacDV] Re: 200 gig hard drive vs. dividing hard imac drive

[Richard Brown]

DVCAM/MiniDV has a data rate of  25 Mbps, or just over 8 MB/sec at 
about a 5:1 compression ratio. The spec of DVCAM is equal or superior 
to Betacam in every important category, according to the SMPTE.  High 
definition MPEG 2 (which the prototyped JVC High Def DV uses to record) 
is spec'd by broadcasters at 19.4 Mbits/sec, which implies tremendous 
compression, perhaps 30:1. Basically, DVCAM and MiniDV should visually 
wipe the floor in terms of picture quality with JVC's consumer high def 
in terms of compression artifact degradation.

The JVC High Def DV uses a special (unto JVC alone) recording process 
because it is recording highly compressed MPEG-2 high definition video 
onto the MiniDV tape. The fact that it is so compressed will allow 
ordinary Firewire and ordinary hard drives to handle the content. This 
is not broadcast quality high def by an stretch of the imagination. The 
inevitable presence of compression artifacts will also make this 
consumer high def useless for esoteric things like transfer to film. 
It's one thing to blow up clean video, and quite another to blow up 
uncorrectable compression artifacts. SDI video on DVCAM would look soft 
due to the tremendous up-resolution required, but the JVC consumer HD 
will shout its compressed origins under such conditions.

The BIG question will be -- how will this JVC oddity fare in post 
production? MPEG - anything has always been intended solely as a 
distribution (after the Final Cut - pun intended) medium, and has never 
been consider a viable editorial medium EXCEPT for online compressed 
streaming content purposes.

However, given the fact that a large segment of the television viewing 
public apparently enjoys highly compressed, horribly artifact laden 
(wherein a movie like "The Others" has dozens of unintended additional 
apparitions), the puzzlement becomes - as the viewing public accepts 
lower quality for quantity, will an independent producer be able to 
take advantage of this odd JVC concoction without the public taking 
notice? The near term novelty of HD TV might fuel this possibility as 
well...

Richard Brown

On Thursday, January 16, 2003, at 11:19 AM, Thubten Kunga wrote:

> FireWire is 50 MBytes/sec (400 bits dIvided by 8 bits per byte) while 
> FireWire 800 is 100 MBytes/sec (800 bits dIvided by 8 bits per byte) 
> sustained throughput. This is analogous to the old ATA66 vs. the newer 
> ATA100 IDE spec. I think that we will be needing FireWire 800 to 
> transfer HDDV from our High Definition DV cameras and desks that will 
> be coming to market later this year.  > http://www.supervideo.com/jvc.htm
>
> Anyone on the list have any experience with High Definition DV yet?
>
> k
>
> On Thursday, January 16, 2003, at 11:08  AM, Michael Winter wrote:
>
>> On Tuesday, January 14, 2003, at 11:57  AM, XXL wrote:
>>
>>>> The bandwidth for firewire 400 is so much greater than you need for 
>>>> dv
>>>> capture that there is enough room to pass the video thru the 
>>>> harddrive into
>>>> the computer and then record it onto the drive.
>>>
>>> According to Maxtor engineers, FireWire 400 is the limiting factor in
>>> performance in many drives now.  It is claimed that newer drives are 
>>> faster
>>> than the bus. ..just what I read.. Have no idea if it is actually 
>>> true.
>>
>> From the research I've done speccing drives, you're information is 
>> correct, at least with respect to sustained transfers.
>>
>> However what the previous poster was referring to is that a real time 
>> video stream has a fixed bandwidth that is much lower than the 400 
>> Mbps that Firewire provides. So it doesn't matter how fast Firewire 
>> or the drives are, as long as they are faster than the DV stream(s) 
>> (which they are -thanks sb).
>>
>> -Mike
>
>
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