Digital8 and Firewire

[Ned]

Can the cheaper Firewire cards from ADS and Pinnacle (both under $200) transfer the full quality signal from my Digital8 camcorder to my PC for editing? What is the format of the file that is stored on my hdd and what is the approximate mb/sec? What are the advantages of getting a package like the DV Raptor?

Thanks in advance.

[Jerry Jones]

Pinnacle never inspires confidence.
(History of buggy products.)

ADS Pyro has trouble with playback
out to camcorder in many cases...
although many users swear the
latest driver fixes the problem...
I'm still seeing reports on the
newsgroups that many people are
experiencing "skips" in the video
playback... EVEN WITH NEW DRIVERS.

The Canopus DV Raptor WORKS. Period.

[Phil Pugh]

I'll second Jerry's comments. Go for a RAPTOR. It's a little more expensive but it works right out of the box.

As for data rates it's 3.6Mb/sec continously. Most new IDE disks can cope with this.

The on-disk format is DV - all you are doing is a 'file' transfer from the camcorder to the computer.

Phil

[Grigory]

Hi,

The file format on disk is certainly DV compressed AVI file.

Digital data is copied As Is from DV camcorder to hard drive, which results in creation of common avi file with a copy of data recorded on tape. There are no files on tape, but a part of tape data becomes standard AVI file on hard drive.


The quality of Firewire card determine only reliability of data copying, but not the image quality inside the file.

I also recommend to go for a working solution like DV Raptor.
Note, it works surprisingly well for all systems everywhere.

Grigory

[Ned]

How much better will the video quality be compared to capturing the video with my G400 marvel as to using the firewire? I did some test captures from my standalone toshiba 2109 DVD player and the quality was acceptable but not overwhelmingly good. I would like the quality to be high enough so that I can edit video on my PC and then output it back to digital8 with as much resolution intact as possible (amateur film maker

[Grigory]

Capturing via firewire is a simple copying of bytes.
This ensures maximum possible quality. For G400, you have to adjust many parameters to keep the quality at the highest possible level, and still you get some drop because of
1) decompression of DV inside camcorder
2) digital to analog signal conversion inside camcorder
3) some (little) noise added on analog path to G400
4) analog to digital conversion inside G400
5) compression to MJPEG
6) decompression inside G400
7) digital to analog conversion in G400
8) some noise (little) added on analog path
9) analog to digital conversion in camcorder
10) DV compression


This is the way from DV data to DV data in the case you simply capture D8 as analog and send video back to D8 as analog. All stages can introduce some quality degradation.
For firewire, you have only byte copying, some none of these stages is present.

If you do editing, you have to add these steps between 6 and 7:
a) applying effect
b) compression to MJPEG
c) decompression of MJPEG

For editing DV via firewire you have:
1. copying compressed DV data bytes
a) Decompression from DV
b) applying effect
c) Compression to DV
2. Copying compressed DV data bytes back

Dv compression is much better than MJPEG, and you also only 2 lossless steps instead of 10 lossy.

However, the quality drop is not such bad as you can imagine fro a chart. Typical video may even look almost identical. However, in complex situations like high contrast, high number of fine picture elements, noisy video produced in nightshot mode or in poor light conditons, pure DV is very much better.

Don't forget that firewire provides you ability to control camcorder from PC with frame accuracy, use timecode effectively and many other very convenient features you cannot get with analog capture cards.

Grigory

[SDDS]

Just wanted to tack on an extra comment here.
I agree with the notion of the card being
used as a transfer only hardware and not a
compressor. I personally use the
MotoDV/DigitalOrigin card and have great results.
The format on mine however is Quicktime instead.
I used to do a lot of AVI stuff with MJPEG and no longer trust AVI.
QT 3/4 has timeline playback BUILT in.
I use Premiere 5.1a and can playback from the
timeline and only need render the couple of
transistions as would normally be expected.

Plus, the MotoDV Studio Package is much cheaper if all you need is DV in/out.

P3-500
128 ECC RAM
G400 MAX
SOHO PCI Ethernet
FastTrak PCI IDE RAID with 81 GB online
Digital Origin Firewire card
Turtle Beach Montego PCI
UW SCSI PCI
All Running on Win2000 only

[Cut ter]

I'm thinking of going fully Digital.
I have read tons of articles on DV / NLE etcs.
How is it that you edit using firewire. I mean after transfering Data to PC.
In MSP or Premiere what compression would you use. I understand that it would only render the transitions and changes, but is it possible to get realtime editing w/Firewire?

[Grigory]

Hi,

I think the comparison of avi and QT is a question of hardware preferences only. For those of us who have avi-oriented DV interface cards, avi is the only choice. As for timeline playback, most serious manufacturers have thier own implementations for avi too.

When you transfer data from tape to hard drive, you get (well...) a media clip, which uses one and only one type of compression : DV codec that is supplied with DV card.
Editing this file you can either keep this compression to be able to send movie back to tape, or use any compression you like for output movie, but you will not be able to send it back to camcorder via firewire.

ALL dv camcorders are only DV movie data storage devices. You cannot use them as generic data storage. The only data format is DV compressed movie.

As for realtime editing, we had here a lot of talks abotu this. To begin a new one, we have to start from a definition of "realtime"

With cheap DV cards, you edit your movie and only changed parts of it are rendered(decompressed, changed, and compressed back to DV).
Three stages are involved:
1. decompression is typically possible slightly faster than realtime, say 80% of realtime on PII 450
2. Frame modification time depends on the effect. Now all these effects are calculated in software, unless you buy very expensive specialized hardware. The time is from 20% of realtime for simple fades, to x100 and more for complex transitions. RT2000 is claimed to be able to do stages 1 and 2 in realtime.
3. When the editor gets modified frame, it has to compress it back to DV. Currently, this requires x3 realtime for software codecs. It is probably possible to get realtime compression with some expensive hardware, or by using uncompressed (analog or digital) video stream from stage 2 as an input of realtime encoder.

Finally, with inexpensive cards you get x4 of realtime for rendering simple effects, and after this time, the editor begins to send data to DV tape with 100% realtime speed.
For a typical movie with effects duration of 20% movie duration, rendering time is approximately equal to movie duration.
After rendering you have data stream prepared to be send to output in DV or analog form.

Actually, you often have to check the effect before final rendering. For simple 2 second effect, you need ~8 sec to generate preview. After you made all previews while editing, the editor has all necessary files and is ready to play them in realtime.
RT2000 offers a lot of realtime effects and transitions, so it comes very close to realtime editing solution.

Interesting: does Matrox have plans to make an addition to RT2000: a card that will be able to take uncompressed digital video as an input via PCI bus, and produce compressed DV stream on the output? Such card will accomplish pure DV and realtime movie production solution.

As home movie maker, I am quite happy with DV Raptor. I spend x10 - x30 realtime or even more in editing, mostly for making decisions, and can easily wait half an hour for final rendering of 10 minutes clip.

Grigory