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Capping
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Ripping Dvds
Obtaining video from a dvd is as simple as connecting your dvd player to your video in jacks, or as complex as adding a dvd player to your system and applying decoding tools to get around the encryption that was developed to prevent you from doing just that. For the first case, you're Capping, and this introduction may provide some assistance to you. In the second case, you're Ripping, and it is beyond the scope of this faq, mainly because of the many fine sites already out there. If you're just starting out, or have been ripping for awhile, the best site that the faqs recommends is vcdhelper, a well laid out and through guide with large number of links to all things dvd.

Capturing Streaming Media
Not a lot of info to report as yet, but after testing I've been able to "trap" about half of the "asfs I've looked at. Don't have a porn site account, and that's where I think this thing would come in handy. Stored on the FAQs, and called ASFRecorder.

Capturing Stills for Previews
Many of the eidting programs come with some form of screen capture, but here's a few notes on a way for anyone on a pc to grab stills -- for AVI's and ASF's, you don't need any extra special software. To really understand making Previews - there's a Great "HowTo" here
    1. ASF. Using the media player, just pause it at the scene you want, and hold ALT and hit Print Screen, then open PAINT, and paste and crop and save as JPG.
    2. AVI. Use the Windows Explorer, Properties, Preview, then again pause, ALT-PrntScrn, then Paint and Paste,etc.
    3. MPG.  You'll need to find a simple mpg player prg other than Media Player because it gives you a black screen with AVI's and MPGs. One that comes to mind, since it's often posted in a.b.m.utilites is Xing 3.x.

Capping Glossary

Artifacts
Imperfections, the pixalation on the frame.  Caused by over compression  and or low quality source. Most of the time you'll notice these on your final product, but often the underlying cause of them comes from the failure to collect data during the cap.
Codec
COmpression & DECompression.  The software algorithm that allows the video to be stored in a compressed format, then decompressed at runtime. Even with so called "software only" capture cards, there is a built in chip that has a software codec burned in to it. Make sure you know this codec, it's limitations, and it's strong suit, and use it's strengths to the max.
Data rate
The Rate, expressed in kilobytes (KB) or kilobits (Kb) per second, which a video & / or the video audio stream is captured at.  In general, given identical frame rate, frame size and codec, a video with a higher data rate will have better quality than a video with a lower data rate. The best cappers tune their capture rate to the maximum their computer configuration can stand.
Drop frame (dropout)
That dreaded loss of frames during the capture process. If your capture software allows, you should monitor this number ( expressed as a percentage of the total ) and never accept a cap with greater than 2% drop out.
Caused by:
a) Hardware Problems - compression chip, hard drive or bus controller - inability to keep up with the data stream from the feed.  Simple solution is to reduce the rate of data. Best solution is replace the slowest component.
b) Software Problems - compression algorithm [codec], the software codecs  inability to 'keep up' with the data rate called for. Simple solution is to change the "save" codec to one more compatible with the hardware codec chip - See Codec above
DV(TV)
Digital Television, and to some extent digital computing, still have yet to come together.  Check this:
January 2, 2002 The Advanced Television Systems Committee (ATSC) has advanced its DTV Application Software Environment (DASE) specifications to the level of Candidate Standard.  The DASE Standard will provide enhanced and interactive content creators the specifications necessary to ensure that their applications and data will run uniformly on all brands and models of DTV receivers while providing manufacturers the flexibility to choose hardware platforms and operating systems for receivers. The Candidate Standard stage is an explicit call for implementation and technical feedback. The DASE-1 suite of specifications is organized into eight logical parts and is available at .
The only current standard of true digital is the 16:9 frame size - a square of the current NTSC 4:3
FPS - Frames per second
This is a count of the number of frames meant to captured each second.
As a point of reference,
   American TV plays at 29.795 fps (60 cycles),
   European standard is 25 fps (with 50 cycles).
See the discussion of Fields for more on this.
Fields
The best way to explain fields is to start off with  the review of  FPS and electricity referred to below. Note "cycles". That is the measure of the number of times the electric current alternates back and forth each second.  Your Tv screen is "refreshed" each 1/50th or 1/60th of a second based on this electric cycle. Each cycle the raster ( the little ray gun in the back of the tube that excites the phosphors on the interior of the front of the screen and causes them to glow ) starts at the upper left, scans an entire row of pixels from left to right, moves back to the left and down a row, and repeats the process until it reaches the bottom right. It then travels back to the upper left, in what is known as the blank interval more familiar to dos program writers who used to use this nano second of time to execute other code in the space occupied by the video memory. Most broadcast quality feeds are composed of an "a" field and a "b" field to match these cycles, with the "b" field slightly offset to create a smoother blend between the pixels of the "a" field. In terms of quality, the b tends to be the lesser of the two fields, and if your capture program allows it, and your computer is having trouble keeping up during capture, turn off the b field.
Frame(s)
Quite simply, a still image that when played at the set fps produces the illusion of a moving image. Frames may be complete in and of themselves, or require information from adjoining frames to complete their image. By using information from adjoing frames, the data rate (amount of the frames' information * the rate at which the frame is to play = data rate) can often be reduced greatly.
HDTV
Well, as of May 1st, 2002, all major broadcast stations (the top 100) should be putting out a HDTV broadcast. The FCC has ruled that June 2007 is the cut off for standard broadcast as we know it now. Because of the differing standards under which they built their digital network cable is behind, and meetings are still taking place over the American HDTV standard - all 5 of them - different than those in place currently in Japan and Europe.  The common theme in all the hdtv and digital tv is the 16:9 framing standard. Stay tuned.
Key Frames
Key frames are frames that are completely built from scratch - they do not rely on prior or future frames for information on their content - each pixel of the frame is contained with the data. In mpg these are referred to as "I" - complete frames, "B" - frames using unchanging data from any number of frames before it, all the way back to the last "I" frame, and "P" frames, frames capable of reading pixel information from frames both behind it and in front of it - two pass variable. When data does not have to be sent again, bandwidth is reduced, but in higher seperations between "I" frames, most encoders will "average" pixels - meaning in broad terms that a dark blue pixel that has a shift to red at the next key frame might be exchanged for purple - a gross example, not true, but it gives you the idea behind it.
As mmasw said:
As a rule of thumb, the only advantage that a large gap between key frames brings is in smaller file size. But at a cost both in Fast Forward and ReWind, and in quality. Quite a few of the default key frame settings I've seen would appear to be at the level for maximum "streaming" ability, which would not have much bearing on their use for usenet.
Cappers seem to set their keyframe interval set to one every 10 seconds.....maybe
higher. At that rate, "fast forwarding" by dragging the cusor means that there is a huge lagtime before the clip resumes play. It's extremely cumbersome....if you want that function.
Because I think that function is important, I always set my keyframe interval to one a second.....sometimes it's even smaller. That way resumption of play after dragging the cursor is nearly instantaneous. 
Even on a huge file, the increase in file size by a small keyfame interval is insignificant.
In the past, it seems, every time I've "asked" a capper about why they have a large interval, they are rather surprised that aspect is under their control.
I'm wondering if that is the case now, or if there is a material reason for the larger, more awkward intervals?
Scene Change
Threshold
It's involved with streaming media - the ability to read forward to
know that an abrupt change it going to occur, and conserve current
bandwidth to compensate for the need to create the entire pixel set
for the first frame.

It's net effect for us in the video groups is mainly that people with
older cpu's or video cards could have the clip "jerk" or even stop
until it was able to catch up to a variable data stream clip. Some
early full screen divx / xvid clips produced this.

Consider scene change threshold as an "advanced Key Frame" concept.
Depending on which codec you're looking at (and any variable bit rate
codec has this feature - either hardwired or software set-able),
increasing or decreasing the setting can improve the quality during
scene change, but at the cost of increased file size and processing
speed.


Capping Basics
The Hardware
You need a computer, a lot of fast, free hard drive space, and VCR, DVD, or camera. Even though it is possible ( and done all the time ) to cap on a 386, today the better caps come from PIII or K7 or better machines.

MOTHERBOARD -- A quality motherboard with a high speed bus makes the data flow from cap card to hard drive easy. The data from your capture device moves from your card across  the bus to the CPU and then again to the IDE controller and on to the IDE Drive (or SCSI controller and SCSI drive). Bus speed on your motherboard should be at least 100mhz, and 133 is better. Speeds above 200 are getting to market now.

FIREWIRE USB -- For USB capture devices, Firewire 1394 has been the standard and was developed by Apple for this very purpose, but has lately been replaced by the 1396 standard, allowing non Apple Dv devices even faster access through to the board.
RAID ARRAY -- a built in Raid array on the mother board ( a device for creating a virtual super fast drive out of 2 or 4 slower drives ) simplifies the storage process. Not all mother boards are created equal, and it doesn't hurt to spot a few boards, and then read the posts in alt.comp.periphs.mainboard.(motherboard-of-interest) about whether they work or not. My own first built in Raid was on a MSI KT266pro and I loved it, but it's also the first board I had that before the year was out fried itself and the cpu. Asus, Gigabyte, and ABit all make boards with Raid arrays built in. And several manufactures make add on Array cards. Try Video Guys for them.
HARD DRIVES -- in two sub classes:
    IDE -- there are two ideas that you need to bear in mind when using IDE drives. The first is that you should always avoid capping anything more than 1/2 of the Hard drives capacity. After about one third in, a ide drives speed begins to drop off, and past half way you'll really notice it. The second is "time-outs". An Ide drive as a built in heat sensor that will periodically cause the drive to stop writing. While there is a built in memory to hard drives to help prevent loss, it still can jam up the flow of data. Your drive should at least match if not exceed the speed of your motherboard's. An ATA 66 ide on a 133 motherboard is a waste. Consider a Raid array.
    SCSI -- While there are many divisions of Scsi types, the immediate benefit over IDE is a lack of the heat sensor / time-out problem, thus no delay to cause drop outs. Even the old Scsi II standard (40 pin) used in a Raid Array could capture at near digital quality. And my last Ultra Scsi III still flies by with 1200x675 caps, that is if I remember to reformat once an awhile.

CAPTURE DEVICE -- gee, that's in the next section.

the Capture Device ( cap card )
There are at least 2 dozen cap cards out there, from mass produced $90-$200 starters, $200 to $600 mid range, and $1000+++ true video capture cards.  You wanta do Tv? - think $10.000 to start.  There are three considerations to step through before narrowing the field down for the right cap card for you.
COMPUTER -- After reviewing what's been discussed above about hardware, you should quickly see that buying a $800 capture device to be used on an old PII with 16 meg of memory might be a bit of Over kill. If your desire is to film, capture, and edit material that will be going into a HDTV DVD then by all means buy a card like this, then get the computer to go with it. For Capture of a standard DVD it might work with the PII. For Capture of  VCD and most net produced content it's overkill. Price for the most part equals ability, when you factor in the bundled software. Know the price of this software (even the "lite" versions) and it will give you a starting point to consider what value they place on the caputure board itself.
CONNECTION -- This is a bit of same as hardware as well. A) If you don't have any free PCI slots, it would be senseless to get a PCI card unless you know you can remove one. Under this case, and for any with a crowded computer, this is the best time to consider an "All in One" Video card / Capture card like the AT and Assess. A USB connected external like the Fast's Dazzle is also a good choice if you already have a firewire port onboard. B) It's best despite the ability of win to share Iraq's if you can get your Capture driver to run solo, reducing the need for the OS to interrupt the cards cycle to check on the need of the device sharing it's IRQ. C) For those considering USB connected devices, remember the key Firewire need. A 1394, or best 1396 USB connection is about twice as fast as a USB2 port, and most certainly will be needed. If you install one of these, consider shutting off your on board USB ports in BIOS to free up resources.
HARDWARE CODEC -- Ever since the day that intel annouced the Intel Smart Recorder, manufactors have been claiming Hardware-compression-less cap cards. I say horse feathers. Every card I've put my hands on that makes this claim has somewhere on it a big fat Compression/decompression chip, including Intels. What most of these people mean is that the through-put of the capture is fast enough that you won't have to compress the signal that much due to the capture device itself.
It's important to know what / whoose chip is on the board your considering because this will tell you what standard capture settings will give you the best results. Many of the lower end cards have older Brooktree 800 series chips, which are only 16 bit color. Cap all day at 24 bit, it still is 16 until your final recompress. Most (if not all) of the first released DV capture devices use a varient of the Quicktime chip - which should have been good, but the mpeg standard moved away from it so fast that I'm not certain anymore if it will be the leader 6 months from now.

Want to post to usenet?
Grab what you can afford, and work at it, ignoring all that is said above.  Many of the posts you see in abme are done with cards costing less than $200.  The cards come complete with some form of capping and editing software.
As a strong aside, when asking for help in abmed, note that the best help will come from those who use the same cap card as you do.  While any capper can help, the hardwired characteristics of each card has it's own flavor.  State which card you're using when you post a help request.

Notes on Mac
One new program for capturing video on the Mac side is called BTV. It only supports quicktime capture, and is limited by the 2 gig file size limit. More info can be found at http://www.btv.org.uk/. One can also use Premiere as well.

Notes on Unix
Linux has support for several capture cards, as well as a great selection of mpeg encoders. You'll not be able to make AVIs, movs or rms. So if you're willing to stick to mpeg, you'll do fine. One of the easiest ways to check a cap cards ability to work in unix is to go to the manufactors site and look at their drivers page for unix /linux drivers. But take it that one extra step and find and use that toll free number or email to make sure before you buy.
In the freeware capping software you might want to take a look at Avifile.  It can now capture and encode to divX 4 as well as 3.11 and a large group of Intel / M$ formats.



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