What's difference between DV and Mini DV ?

[dragmore]

What's difference between DV and Mini DV ?
Is it just the tape size?

Another question:

If i have no need for realtime rendering in a DV/firewire solution would a card like miroDV200 do? instead of rt2000 or dv500?
Isnt the video quality the same?

[DrMordrid]

This can be confusing because the term "DV" can refer to the DV codec or to the various tape form factors that can have DV encoded data recorded on them.

First a definition of terminology for any newbies that are listening:

mb/s = megabits/sec
mB/s = megabytes/sec
mb x 8 = mB

DV the codec digitizes video at a rate of 25 mb/s, or about 3.5 mB/sec. A 50 mb/s variant also is used, but this is really two parallel 25 mb/s streams and not a single 50 mb/s stream.

miniDV the tape format is a 6.35 mm wide tape recorded at a speed of 18.81 mm/sec and a track pitch of 10 microns in SP mode and mounted in a rather small shell.

There are several DV tape form factors such as miniDV, DV Standard, DVCAM and DVCPRO Small. The various form factors differ mainly from from each other in the tape speed, track pitch or the dimensions of the plastic shell.

You can read more about DV at Adam Witt's site:

http://www.adamwilt.com/index.html

The video quality stored on your disk will be the same if you use just a basic IEEE-1394 card to import the DV data. The differences will come during the editing process.

One of the things a card like the RT2000 gives is the ability to edit DV on the timeline and to export it at full quality.

Some editors or card/editor combos import DV from the disk only to transcode it to another codec for editing. This can cause degradation of the data when it's exported back to the DV format.

This is a big deal because DV has high resistance to artifacting when special effects, transitions, filters or titles are applied. Applying the same effects to a transcoded stream can cause a noticable loss of detail and quality in the output data.

Dr. Mordrid




[This message has been edited by DrMordrid (edited 04 December 1999).]

[dragmore]

Hey thx DrMordrid!

What do u mean by "The differences will come during the editing process"? Will the different DV format's affect the editing process?

Is there cheap DV input/output cards that edit in full DV format all the way? Instead of converting to another format? That are cheaper than RT2000 and DV500?

Best regards Dragmore

[Brian Ellis]

Hey, Doc

I'm going to take you task over yorur definitions. You will cause one helluva lot of confusion.

What I am about to state is interpreted from the ISO standard on units and definitions.

First of all, unit prefixes:

kilox = 1 000 * x abbreviated k e.g. 1 kilometre = 1 km (note the gap between the 1 and the k)
megax = 1 000 000 * x abbreviated M e.g. 1 megahenry = 1 MH
millix = x / 1 000 abbreviated m e.g. 1 millifarad = 1 mF
microx = x / 1 000 000 abbreviated µ e.g. 1 microsiemen = 1 µS

These are absolutely inflexible except that a vowel may be dropped where the unit starts with one (e.g. 1 megohm rather than 1 megaohm)

With a few named exceptions, all units named after persons or places must be written with a lower case initial letter and their abbreviations are in upper case, as in many of the above examples. All other units must be abbreviated with a lower case initial.

Unfortunately, there are thousands of abbreviations required to convey all notions of quantitative measurements and only 26 letters in the Latin alphabet and 24 in the Greek one (with some overlap), * 2 for upper and lower cases. This means that, to avoid ambiguity, one has to be very precise with abbreviation. There is an unwritten rule that any new unit with three letters or less must never be abbreviated nor pluralised. An outstanding example is in atmospheric pressure where, if my memory serves me right, 760 mm Hg = 1014 mbar (millibars). If no confusion can exist, longer units may be abbreviated by using 1 or more letters but care must be taken to avoid ambiguity.

I therefore state categorically the following with relation to data transmission:
1 B = 1 baud, a unit used for coded letter transmission speeds, such as in telex/teletype, named after Baud, a French scientist. Over later years, it has also come to mean 1 bit/s, so that B/s or Bps is false in this context.
1 bit = 1 binary digit and can never be abbreviated further, as it is already an abbreviation of three letters
1 byte = (usually in our context, but not necessarily) 8 bits. This is often abbreviated to 1 b, but it is more unambiguous to use 1 by.

I recommend that the baud be dropped in the IT context as it can mean all things to many people, but this means that the abbreviation B should not be used.

To correct your definitions:
Mbit/s = megabits/second = 1 000 000 bit/s
Mby/s = megabytes/second (possibly Mb/s)
Mbit x 8 = Mby

Sorry to drop down on you like a tonne of bricks but I think this is VERY important not to add more confusion where there is already far too much. I am very allergic to the misuse of units because I sit on various standardisation committees, including ISO ones, and we learn very rapidly what is and is not acceptable. BTW note also that I use the ISO recommended space as the thousands divider and , rather than . as the decimal point. The latter is interesting, in that Germany has used komma and France virgule (bothe meaning comma) for the decimal divider, rather than the Anglo-Saxon point for many years. ISO now recommend it, always with a leading zero when it is less than 1, because many computer fonts have a point which is almost invisible. Just compare 0,1 with .1 for clarity.

Anyway, Doc, I may be pedantic, but with a reason. Please forgive me.

------------------
Brian (the terrible)



[This message has been edited by Brian Ellis (edited 04 December 1999).]