AVI Graphics Format Overview

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AVI Graphics Format Overview

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MPEG compression option. Open an AVI, Save As an MPEG, and see what
happens (get some coffie, as it'll take a while ;) I checked it out
on a stream where CMPEG gave up and the Corel's conversion did make
a wonder. (If you like to see the result, download my 'Liquid Beatles'
morph clip, 1 Mb: http://www.proteon.nl/synth_art/movies/cross.mpg).

4. Ulead's MPEG converter (www.ulead.com) seems to be the major
player (priced below $250) on the Windows arena. I've heard good
references about their MPEG's quality, but I feel that their
biggest advantage is good integration with Windows and AVI format.
If I'm not mistaken, a very slow codec.

5. Don't mess with DARIM Vision's codec (Korea). I've tried their
demo, it produces low-quality crap. Though fast and cheap (you bet :-).

See my MPEG clips, fractals, morphs, and in general lots of
advanced graphics at
http://www.proteon.nl/synth_art/

Hope this helps,

Valery
http://www.proteon.nl/synth_art/movies.html
---------------------------------------------------------------

In addition to the above, there is MPEG Maker from
VITEC-HTS (formerly Vitec Multimedia). Vitec is:

Vitec
4366 Independence Court, Suite C
Sarasota, FL 34234
Voice: (941) 351-9344
FAX: (941) 351-9423
http://vitechts.com

CeQuadrat makes a software-only AVI to MPEG converter called
PixelShrink. CeQuadrat is:

CeQuadrat
1804 Embarcadero Road, Suite 101
Palo Alto, CA 94303
Voice: (415) 843-3780
FAX: (415) 843-3799
http://www.cequadrat.com/

And the freeware kit CONVMPG3, a collection of MS-DOS
utilities that can be used to convert AVI to MPEG-1 or
MPEG-1 to AVI. CONVMPG3 includes Stefan
Eckhardt's CMPEG MPEG-1 encoder mentioned above
but also includes utilities to generate the sequence
of Targa files required by CMPEG. The URL for CONVMPG3 is:

http://www.powerweb.de/mpeg/msdos.html

avi2mpg1 is a freeware command line application for Windows 95/NT
that can convert AVI to MPEG-1, supports audio, video, and
interleaved audio/video.

http://www.mnsi.net/~jschlic1/

MainConcept's MainActor product now (March 1997) includes
add-on modules to output MPEG-1 and MPEG-2. With these add-on
modules, MainActor can convert AVI to MPEG-1 or MPEG-2.

Marcus Moenig at MainConcept provided an evaluation copy of the
MPEG-1/2 modules. In tests, these modules could convert AVI files
to MPEG-1 that could be played using the ActiveMovie software
MPEG player shipping with Microsoft's Windows 95 OSR2.

MainConcept is:

MainConcept
http://www.mainconcept.de

The URL for Ulead is:

Ulead MPEG Converter
http://www.ulead.com/

On May 6, 1997, Xing announce a new product, the Xing MPEG Encoder 2
which accelerates MPEG encoding using Intel MMX instructions on PC's.
The original Xing MPEG Encoder did not use MMX instructions.
The Xing MPEG Encoder 2 can convert AVI and WAV files to MPEG-1.

The URL for Xing is:
Xing Technology Corporation
http://www.xingtech.com/

Ligos Technology markets an LSX-MPEG Encoder to convert
AVI to MPEG-1 and MPEG-2

Ligos Technology
1475 Folsom St. Suite 200
San Francisco, CA 94103
+1-415-437-6137
+1-415-437-6139 FAX
info@ligos.com

http://www.ligos.com/

For further information on the MPEG digital audio and video
format see Tristan Savatier's comprehensive MPEG site:

http://www.mpeg.org/

and The MPEG Home Page:

http://drogo.cselt.it/mpeg/

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How to capture screen to AVI Files

Microsoft Camcorder

Microsoft distributes a free screen capture utility called
Microsoft Camcorder (sometimes abbreviated MSCamcorder). Camcorder
can save screen captures as AVI files or a .EXE file.

http://www.microsoft.com/msoffice/office97/camcorder/default.htm

HyperCam

See the following posting from Greg Kochaniak dated 5/10/97 from the
comp.archives.ms-windows.announce newsgroup.

I have uploaded to Simtel.Net:

http://www.simtel.net/pub/simtelnet/win95/mmedia/hycam119.zip
ftp://ftp.simtel.net/pub/simtelnet/win95/mmedia/hycam119.zip 251872 bytes

hycam119.zip HyperCam v1.19 AVI screen capture for Win95,NT

HyperCam v1.19 captures the action from Windown 95 or NT screen in any
graphics mode, including cursor movements and sound, and saves it to
standard AVI movie files. Perfect for demonstrations, presentations
and tutorials.

Special requirements: Windows 95 or Windows NT.

Changes: Fixed two problems: starting recording in 256 color mode would
produce sometimes invalid AVI files (when, upon minimizing HyperCam
window for recording, another window with a different palette would come
to front and realize its palette). The other problem: selecting AVI file
name with Browse button would not always work correctly.

hycam119.zip has replaced hycam118.zip.

Shareware. Uploaded by the author.

Greg Kochaniak, Hyperionics
gregko@hyperionics.com
http://www.hyperionics.com/

SnagIt

TechSmith Corporation markets a Microsoft Windows product called
SnagIt which can capture the screen to AVI files. SnagIt also can
capture the screen to still image formats such as BMP.

http://www.techsmith.com/

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Authoring Tools to Create AVI Files

A wide variety of 2D and 3D animation applications as well as other
multimedia authoring tools generate AVI files directly. This is
especially true for Windows versions of applications, since Microsoft
provides an API for creating AVI files. A list of applications
that can create AVI files follows.

LightWave 3D 5.5 for Windows 95 and Windows NT

LightWave is a popular 3D modeling and animation program
widely used in broadcast television. LightWave can do almost
anything and supports third party plug-ins to add features that
it lacks.

NewTek
Note: According to product literature on the NewTek Web site.

http://www.newtek.com/

Caligari Truespace 1,2, and 3 for Windows

Caligari TrueSpace is a popular low-end 3D modeling and animation
program. Traditionally, TrueSpace has been polygon based limiting
its usefulness for modeling organic forms. TrueSpace 3.0 adds
some organic features.

Caligari Corporation
Note: Confirmed from personal use of Caligari TrueSpace.

http://www.caligari.com/

Fractal Design Ray Dream Studio for Windows

Ray Dream Studio is a suite of 3D modeling, animation, and rendering
tools.

Fractal Design
Note: According to product literature on Web site.

http://www.fractal.com/

Macromedia Director 6.0 for Windows

Macromedia Director is a widely used authoring tool for creating
interactive 2D animations such as presentations, multimedia for
kiosks, prototypes of user interfaces, and similar uses. Director
can also produce straight 2D animations appropriate for AVI files.

Macromedia
Note: According to product literature on the Macromedia Web site.

http://www.macromedia.com/

CorelMOVE

Corel's CorelMOVE animation software can export AVI files.

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How to create AVI files from analog video:

Video Capture Cards

On Intel based PC's, use a video capture card to convert analog video
from video tapes or video cameras to AVI files. A PC video capture card
is typically either a 16 bit ISA bus card or a 32-bit PCI bus card that
plugs into the 16 bit ISA or 32-bit PCI slots in your PC motherboard.
32-bit PCI bus cards are steadily replacing 16-bit ISA bus cards.
Most video capture cards have either a composite video connector or
both a composite video and an S-Video connector. Most video capture
cards perform compression of the video in hardware or firmware on the
video capture card before tranferring the compressed video over the ISA
or PCI bus to the PC hard drive.

Most video capture cards only capture video. They do not contain audio
capture. Audio capture is done through the audio or sound card of the
computer. It is increasinly common to have the audio input and output
hardware built into the motherboard. The computer may not have
a physically distinct sound card.

Sound cards usually have a Microphone input jack, a Speaker or
Headphone output jack, a Line input jack, and a Line output jack.
Line input and the microphone input are not interchangable. The
jacks use different electrical signals. Most users will use
the microphone for input and speakers or headphone for output.

Video Capture in Video for Windows

Under Microsoft Windows, video capture cards come with a Video for
Windows capture driver (CAPTURE DRIVER). The capture driver exports
standard functions (including some dialog boxes for user interaction)
that any Video for Windows software application can call.
Any Video for Windows video capture application, including video
editing applications that support video capture, can and must use this
Video for Windows capture driver to capture video.

Windows 3.x, Windows 95, Windows NT 3.51, and Windows NT 4.0 all use
Video for Windows capture drivers. ActiveMovie 1.0 for Windows 95 and
Windows NT 4.0 does not provide a mechanism for video capture, only
video playback. Video for Windows continues to be the software
component for video capture.

The capture driver may consist of a single file or multiple
files. The capture driver is identified by the name MSVIDEO (in
the SYSTEM.INI file in Windows 3.x and Windows 95 for example).
In Windows 3.x and Windows 95, the SYSTEM.INI file will contain
a line such as

MSVIDEO = C:\PROSHARE\ISVRPRO.DRV

ISVRPRO.DRV is the name of the video capture driver used by
Intel's Smart Video Recorder Pro in the Intel ProShare
video-conferencing system.

where MSVIDEO points to the top-level file that exports the
standard Video for Windows functions for the capture driver.
This file may in turn invoke other separate files that form
the rest of the video capture driver. For example, the
installation program for the miroMEDIA PCTV TV Tuner and
Video Capture Card installs eleven (11) different files
to support the Brooktree Bt848 video capture chip on the
card. This card consists of some connectors, a few resistors
and capacitors, and the Bt848 chip.

In Windows 95, users can view and configure the video capture driver
by selecting System in the Windows 95 Control Panel. Then select the
Device Manager tab. System | Device Manager is actually a user friendly
interface to the Windows 95 Registry which contains all of the
information about a device such as names and locations of driver
files, hardware resources used, and other data in a complex database.
The Device Manager contains icons representing all the devices
installed on the computer. The video capture card and associated
driver will appear either in the "Sound, video and game controllers"
category or "Other Devices".

Each device has "Properties". Users can view and change the properties
either by:

(1) Click once on the device icon in System | Device Manager to select
the device.
(2) Click once on the Properties Button in System | Device Manager.

(1) Double-click on the device icon in Device Manager.

The Device Properties usually have a General, a Driver, and a
Resources tab. The Driver and Resources Tabs may be absent in some
cases.

Users can usually determine the version of the device driver
from the Driver tab of the Device Properties in System | Device
Manager. The Driver tab usually lists all of the files
installed on the system that make up the device driver.

Use the Driver tab to install or update the video capture driver. The
Driver tab contains a Change Driver... button. Clicking on the Change
Driver... button will bring up a list box with the devices and drivers
known to Windows 95. The relevant video capture card and driver may
be in this list. The user may need to provide a disk or CD-ROM with
the drivers and a Device Information (INF) file. If the driver is not
on the list of available drivers, the user must click on the Have
disk... button to load the drivers from the disk or CD-ROM using an
INF file. The INF file contains the information telling Windows 95
how to install the capture driver, including which files to install
where on the hard disk and what changes to make to the Windows 95
Registry and the INI files.

Use the Resources tab to view and change the hardware resource
settings: the IRQ levels used, the DMA channels used, and the I/O
addresses used by the video capture card. It is not uncommon for a
newly installed video capture card to have an IRQ conflict with other
devices on the system. Often Windows 95 will detect the conflict but
fail to resolve it.

Windows 95 automatically assigns resources such as IRQ levels to
devices such as video cards. Windows 95 is supposed to select
IRQ levels that do not conflict. This does not always work. To fix, try
deleting the device from the Device Manager and restarting Windows 95.

TO DELETE A DEVICE FROM DEVICE MANAGER

(0) Make sure that you have the installation CD-ROM or disks with the
device driver software for the device BEFORE you delete it!!!

(1) Click on the device icon in Device Manager.
(2) Presss the delete button on your keyboard or click the Remove
button on System | Device Manager.

When Windows 95 restarts, it will again automatically detect the
hardware, install the necessary drivers, and configure the hardware.
If Windows 95 does not have the necessary drivers it will prompt the
user for a disk or CD-ROM with the needed drivers. As above, the disk
or CD-ROM will need a Device Information or INF file to tell Windows
95 how to install the needed drivers. On a second or third try,
Windows 95 may get it right. Users must delete the device before
restarting Windows 95 to force Windows 95 to auto-detect, otherwise
it will simply use the information currently displayed in Device
Manager.

If deleting the device from Device Manager and restarting Windows 95
fails to fix the problem, the user can manually set the IRQ level and
other resources through the Resources tab in the Device Properties in
System | Device Manager. Uncheck the "Use automatic settings" check
box. Then, the user can manually change the IRQ, DMA, and I/O
settings. Note that this disables the automatic configuration of the
device and can cause other problems. In some cases however there is
no choice but to manually set the resources.

In Windows 95, users may also view and configure some video capture device
information by selecting the Multimedia icon (applet) in the Windows
95 Control Panel. Then select the Advanced Tab. Then select the
Video Capture Devices icon from the icons in the Advanced Tab. This
will show the installed Video for Windows capture drivers. The
IRQ, DMA, and I/O resources usually cannot be set through the Multimedia
icon; users must use System | Device Manager in the Control Panel.

Typically, when a user installs the software for a video capture card,
the installation will install the Video for Windows capture driver for
the video card, Video for Windows if needed, non-standard Video for
Windows compression drivers, and some video capture and editing
applications.

Microsoft shipped a simple Video Capture application called
VidCap, a 16-bit application, with the original 16-bit Video for
Windows (full, not run-time). There is also now a VidCap32, a 32-bit
video capture application. Many other applications such as Adobe
Premiere support video capture.

The video capture drivers provide a Video Source dialog box for
selecting the analog video input format, connectors, and other
options. The Video Source dialog box varies from video card to
video card. It can include options to adjust the brightness or
color of the video image.

The capture drivers also provide a Video Format dialog box for selecting
the color format (image format or pixel format) of the image, the image
size to capture (such as 320x240 or 160x120), whether to utilize hardware
compression built into the video capture card, and miscellaneous
other features.

Users can access the Video Source and Video Format dialog boxes through
their video capture software application. In VidCap, select the
Options menu. Then Video Format... to get the Video Format dialog
box. Video Source... to get the Video Source dialog box.

See below for further discussion.

Analog Video Formats

Composite video signals are analog signals that combine luminance and
chrominance (color) information in a single analog signal that can be
transmitted over a single wire or stored in a single track on an
analog magnetic tape. The NTSC video signals used by commercial
television sets in the United States and Japan are an example of
composite signals. Composite video is particularly prone to errors in
reproducing exact colors due to the overlap of the color and luminance
signals. Video professionals jokingly refer to NTSC as Never The Same
Color.

S-Video video signals separate the luminance and chrominance
information into two separate analog signals that can be transmitted
over two separate wires or stored in two separate tracks on an analog
tape. S-Video is generally superior to composite video in reproducing
colors correctly. The S-VHS and Hi8 video tape standards use S-Video.
Ordinary VHS video tape uses composite NTSC signals. Thus, in
general, using an S-VHS or Hi8 video camera with S-Video output to
provide the analog video signal to the S-Video input of a PC video
capture card will provide better video quality.

A third type of video signal is component video. In component video, the
luminance (Y) and two color difference signals (U and V or I and Q) are
separated into three separate analog signals that can be transmitted
over three separate wires or stored in three separate tracks on an
analog tape, or digitized separately. Component video is used in
professional video production and provides the best quality and the
most accurate reproduction of colors. The professional Betacam SP video
cameras use component video. The current generation of widely used
PC video capture cards do not provide component video inputs.

Capture with Motion JPEG Compressed Video

Typical PC video capture cards store the digitized compressed video as
an AVI file using Motion JPEG compression. Motion JPEG is used
instead of other compression schemes because each frame is compressed
separately. This allows frame accurate editing of the AVI file after
capture. If a compression scheme that uses frame differencing - where
a frame is stored as the differences between the frame and a previous
frame (such as MPEG) - is used, it is difficult to edit the video.

Typical PC video capture cards are bundled with non-linear video editing
software such as Adobe Premiere which can be used to edit the Motion JPEG
compressed AVI file and ultimately compress the edited AVI file using
compression such as Cinepak using frame differencing for maximum
compression.

PC video capture cards usually compress the video using a lossy
compression scheme such as Motion JPEG or MPEG because uncompressed
video places very high demands on the bandwidth of the ISA or PCI bus
and on the bandwidth to the hard drive. In addition, uncompressed
video can fill even very large hard drives very quickly.

Capture with Uncompressed Video (Color Formats)

A number of video capture cards such as those based on the Brooktree
Bt848 and Bt848a video capture system chip save uncompressed video
in alternative color formats to the common 24 bit RGB color format.
Such as the 15 bit RGB color format or YUV9 color format. These
formats represent a pixel with less than 24 bits, reducing bandwidth
and storage requirements. Color formats may also be known as
IMAGE FORMATS or PIXEL FORMATS.

24 bit RGB is almost universally supported. Other color formats may
not be supported by graphics software, video editors, or playback
drivers. Beware problems such as inability to play an AVI file or
view a BMP may occur with AVI files or BMP still images created with
some color formats.

Color Formats Section

PC video capture cards are usually bundled with application software
and drivers to perform video capture such as Microsoft's VIDCAP.EXE
(16 bit) or VIDCAP32.EXE (32 bit) or Intel's SMARTCAP.EXE or other similar
software.

Video capture drivers may provide the ability to select different
color formats for uncompressed AVI video, such as RGB15 or YUV9. With
Vidcap and Vidcap32, select Options | Video Format ... to set the
color format for a video capture session and file. Video Format ...
invokes a Video Format dialog box provided by the video capture
driver; this dialog box differs from capture card to capture card.

Users can usually use the Video Format dialog box to select the
size (resolution) of the captured video (such as 320x240 or
160x120 pixels). Users usually can select the color format which
may be identified as IMAGE FORMAT or PIXEL FORMAT.

NOTE: Windows 95 and Windows NT require different device drivers.
Most video capture cards have drivers for Windows 95. Only some
have Windows NT drivers. Video capture cards that have Windows NT
device drivers and therefore can be used under Windows NT are listed
at the end of this section.

Recent Video Capture Cards (PCI)

Some current (1/11/97) popular PC video capture cards that generate
AVI files are:

Digital Processing Systems (DPS) makes high end video capture cards
for the broadcast and studio markets. Some of these cards can
capture video on the PC. Some of these cards are designed for
Windows NT and include Windows NT device drivers.

http://www.dps.com/

FAST AV Master PCI 60 field/60fps with Motion JPEG, Includes Ulead's
Media Studio Pro digital video editing application.

FAST Web Page

Truevision Bravado 1000 50/60fps 32-bit PCI video capture board with Motion JPEG, Includes Adobe
Premiere 4.2 Full Version

Truevision Web Page

MiroVideo DC30 PCI, complete non-linear video and audio editing for
Windows 95, Includes Adobe Premiere 4.2 Full Version

miro Web Page

Azeena Vision 500 640x480 30 fps Motion JPEG PCI Capture Card
Up to 3:1 compression.

Azeena Web Page

Hauppauge WinTV PCI TV-tuner and Video Capture Cards.
This is a family of TV-Tuner and Video Capture cards.
Built around the Brooktree Bt848 video capture chip.

Hauppauge Web Page

Winnov Videum AV, Half size ISA card, composite and S-Video
input, claims to capture 352x240, 24 bit, AVI videos at 30
frames per second (must be compressed to fit across ISA bus - JFM)

Winnov Web Page

Intel Smart Video Recorder III, a 32-bit PCI card that uses Indeo
video compression. Includes a composite (NTSC) video input and an
S-Video input, RCA and S-Video cables, Asymetrix Digital Video
Producer and Asymetrix WebPublisher.

Intel Page

U.S. Robotics markets the Bigpicture Video capture card and NTSC
camera for about $249.99 (7/22/97). The video capture card is a PCI
half card with a single RCA jack for the NTSC composite video in and a
+5 Volt, 1 Amp power output jack for the NTSC camera. The video
capture card uses the single Brooktree Bt848 chip, a complete video
capture system on a single chip.

Personally, I was impressed that they could get the entire video
capture system on a single chip. More information on the Bt848
can be found at:

Brooktree Bt848 Press Release

Bigpicture can capture NTSC composite video at 30 frames per second at
320x240 or 160x120 resolution.

Bigpicture also comes in versions with U.S. Robotics modems. The idea
is that this can be a PC video phone.

Bundled software includes Kai's Power GOO Special Edition, Asymetrix
Digital Video Producer to capture and edit video, VDONet's VDOPhone (trial
edition), and VDONet's VDOLive player.

MINI-REVIEW

I intalled the Bigpicture video capture system under Windows 95b (OEM
Service Release 2) on a 200 MHz Pentium with MMX, 32 MB RAM, two
Western Digital IDE hard drives (2GB and 5 GB), and a 12x CD-ROM.

The installation was difficult due to resource conflicts. At first
the video capture card appeared to conflict with the SupraExpress 336i
PnP modem in my PC. After reinstalling a few times, the video
capture card started to work, but the modem stopped working. A conflict
between the modem (an ISA card modem) and the COM1 serial port was
reported in the Windows 95 Device Manager (Control Panel | System |
Device Manager tab). I fixed this by disabling the automatic
settings on the modem and changing the IO address. I left the COM1
port (which I don't use) and the modem using the same IRQ (Interrupt
Request) level.

While the documentation provides some pointers on these conflicts, I found
the problem frustrating and difficult to fix although I am moderately
familiar with PC installation and configuration.

Once fixed, the camera and video capture card worked fine. My modem
seems to work fine. I can capture video and use the modem at the same
time.

U.S. Robotics
7770 North Frontage Road
Skokie, IL 60077-2690

http://www.usr.com/

Old Video Capture Cards (ISA)

Some widely used older, 16-bit ISA cards, are:

Video Spigot from Creative Labs
- 16-bit ISA Card
- RCA Jack for Composite (NTSC/PAL/SECAM) Video Input
- S-Video Connector
- Windows 3.x Drivers (16 bit)

Media Vision Pro Movie Studio
- 16-bit ISA Card
- RCA Jack for Composite (NTSC/PAL/SECAM) Video Input
- S-Video Connector
- Windows 3.x Drivers (16 bit)

Intel Smart Video Recorder Pro
- 16-bit ISA Card
- RCA Jack for Composite (NTSC/PAL/SECAM) Video Input
- S-Video Connector
- Windows 3.x Drivers (16 bit)
- Version 2.20.061 (known to run under Windows 95)

The Smart Video Recorder contains chips to accelerate
and implement Intel's Indeo 3.x and YVU9 proprietary formats.
These allowed it to capture video with Indeo compression on 486
machines even though Indeo encoding is very compute intensive.
The special chips on the board encoded the video instead of the
PC's CPU.

Intel is no longer supporting the Intel Smart Video Recorder
(Oct. 1997). Drivers and other support information are still available
at the Intel Web site.

I've successfully installed and used the Intel Smart Video
Recorder Pro on two different machines under Windows 95 with
Driver Version 2.20.061 of the drivers for this card.

Video Capture through PC Parallel Port

A few products enable video capture through the parallel port of
your PC. In principle, this eliminates the difficulties of opening
your PC case and installing a video capture card. A parallel port
capture system consists of a camera and/or adapter that plugs into
the parallel port of your PC and some associated software - usually
Microsoft Windows drivers and applications.

Alaris QuickVideo Transport

Alaris QuickVideo Transport is an adapter that plugs into a PC-compatible
Parallel Port with 25-pin connector. QuickVideo Transport accepts analog
video in NTSC, PAL, and SECAM from RCA plug/composite and S-Video sources.
It can be used with Camcorders, Digital Cameras, and VCR's.

Alaris Corporation
47338 Fremont Boulevard
Fremont, CA 94538
(800) 317-2348 (Voice)
(510) 770-5700 (Voice)
(510) 770-5769 (FAX)

sales@alaris.com

http://www.alaris.com/

http://www.dartek.com/products/qvtransport.htm

Connectix QuickCam

Color QuickCam is a small solid-state camera that plugs into the
PC parallel port.

http://www.connectix.com/

What to do about horizontal tearing in the video?

In horizontal tearing, part of the video is displaced horizontally
from where it should be. For example, a flag pole might be displaced
to the right creating a zig-zag or even a break in the pole.

In the diagram below, think of each line as a video scan line:

Tearing is a common problem when capturing video from the output of an
analog video tape such as a VCR. It can happen in other contexts as
well.

Analog video such as NTSC, PAL, and SECAM composite video has a
sychronization signal at the end of each horizontal scan line and a
vertical synchronization signal at the end of each frame.

The motors and mechanical parts in the transport mechanism of a
video tape player can slip slightly, causing the analog signals and
horizontal synchronization signals to arrive at slightly incorrect
times. Video monitors, capture cards, and other video equipment
have a tolerance for jitter in the timing of the synchronization
signals. Tearing occurs if this tolerance is exceeded.

Digital video capture cards can be very sensitive to the timing jitter
in the output of video tape players. Tearing will occur because the
synchronization is off. Capture cards are frequently more sensitive
than analog video monitors and other analog video equipment which are
better designed to handle timing jitter in the analog signals.

Devices called Time Base Correctors (TBC) can adjust for jitter in
the timing of the analog video synchronization signals and other
distortions of the analog signals. TBC's are available as plug-in
cards for PC's and as black boxes inserted between the video
source and the video capture card.

Time Base Correctors are available from:

Prime Image Inc.
http://www.primeimageinc.com/

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Hard Drive Video Capture Issues

Digital video capture requires writing data to the PC hard disk
at sustained very high data rates. The higher the resolution and
quality of the digital video, the higher the data rate the hard disk
must handle.

1. Defragment the hard disk. This allows the PC to write the
digital video (the AVI file) to contiguous disk sectors without
stopping to skip the drive head over used regions.

2. Scan the disk and fix any bad sectors if possible.

3. Conventional hard drives pause the drive heads for thermal
recalibration which slows their ability to write data to the
hard disk. Special AV (Audio/Video) hard drives (which cost
more) disable the thermal recalibration during data writing.

This supposedly allows an AV hard drive to capture higher video
data rates. Note that you can capture video onto conventional
hard drives. People do this all the time. But for very high
end video capture, you may need a special AV drive.

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