Background.

AccuView is the name of a reference design for a TV and Video Capture/Overlay card from Pixel Semiconductors, a multimedia subdivision of Cirrus Logic .  To make life difficult for us, Cirrus decided they wanted to desolve the company Pixel.  This situation makes it next to impossible to get any documentation or information from them.  They are generally very good about giving information on their chipsets but no one seems to know who to ask what was done with the older design manuals.  Also, most chips used in this design have been discontinued so they are not really willing to support anyone (although companies are still selling hardware based on these designs).

First off, here are some name aliases that can be used throughout any discussion of an AccuView TV/Video card.  Reveal packaged this card and called it Reveal TV-500.  The majority of these cards were problably sold as Reveal cards and you can still find them cheap at auction sites. Packard Bell did the same and called it the PBTV 4.

There are at least two companies that sold compatible cards: Aztech sold one called Aztech TV/Video 500 and Comp Express sold one called Comp Express TV/Video.  If you find any software that runs on one, it appears to work on any of them.

Warning: There are plenty of cards out there with the name PBTV 5.  It is *NOT* compatible with PBTV 4 software and requires it to be pluged in to an S3/Brooktree Video Capture card built in to Parckard Bell computers that it was originally sold with.  It contains a Philips FI1236MK tuner like the accuview design and is sometimes confused for it.

Tech Specs.

Cirrus had a good block diagram on their web page but removed it.  I have a local copy that shows an overview of the AccuView reference design .

Inputs include:

• RCA connector
• Stereo jack (to add sound for the RCA video in)
• F-connector for cable
• VESA Feature Connector  (not on face plate)
• Optional VGA input connector

The hardware can manually switch a relay between video coming from the VESA Feature Connector or passthrough the unmodified VGA signal coming from your regular VGA card.  Note that TV overlay is not supported during passthrough.  Passthrough mode is nice when your not using the TV tuner and want to display graphics that are higher then the VESA Feature Connector can carry.

Cards that do not have the optional VGA input can only display graphics that come over the VESA Feature Connector.  It is always an option to manually move your monitor cable to your normal video card and display graphics using it.

Outputs include:

• VGA Connector
• 4-pin audio-out.  I've seen two types of cables that come with cards.  The first allows you to hook the output to a soundcard's CD player 4-pin audio input.  The other cable allows you to hook the output to any standard mini-stereo jack.

• Philips FI1236MK - Video Tuner - This chip will attempt to tune in a signal that you request.  A scan feature exists to find a channel.  This chip's output is fed into the TDA8708 so that the video can be digitized.
• Philips TDA8708 - Video Analog input device interface.  A/D converter.  Accepts up to 3 analog inputs and outputs 1 digital signal.  1 input comes from the RCA connector, 1 input from the FI1236MK, and outputs one of these to the SAA9051 chip.  This card has at least a couple pins hooked directly to the SAA9051.  Input selection is controlled by communicating to the SAA9051 via I2C.  Please note that in the block diagram the "decoder" block is both the TDA8708+SAA9051.  Accesses to both chips are always done through the SAA9051 chip.
• Philips SAA9051 - Multistandard TV Decoder - Takes digital input from TDA8708, decodes picture according to a few supported TV standards, and converts to what CL-PX1070 wants.  This is an outdated chip but I'm assuming its replacement chip, the SAA7151B is similar enough for reference.  The SAA7151B doesn't document how to control the TDA8708 though.
• Pixel CL-PX1070 - Digital Video Processor - Complete overkill for its application here but promises some neat hack-factors (digital effects like fade-in/outs, picture-in-picture, etc).  Scales video and a few other things and sends to CL-PX1085 to be displayed for user.  Screen capture and VBI capture is also done at this chip back to ISA bus.
• Pixel CL-PX1085 - Enhanced MediaDAC(TM) - Its basically a stardard VGA chip (supports lots of VGA registers anyways).  Takes video from CL-PX1070's frame buffer and overlays it onto a VGA signal coming over the VESA Feature Connector and sends it out to a VGA output connector.  This link is actually to the pin compatible, enhanced CL-PX2085.  You will also see reference in software to a CL-PX2080 , which is basically the same chip but doesn't fully support the VESA standard.
• Pixel CL-PX0001 - Similar in concept to the CL-PX0002 which is used by the PixelView card.  Seems to be a custom chip containing glue logic with such things as a bus controller, I2C interface , plus numerous Input/Output pins for general control of sound, relays, and such.
• Philips TEA5581 - PLL TV (BTSC) Stereo Decoder - One of their more simplied stereo decoders.  It doesn't do any extra stuff like SAP decoding.  But, hey, it does output stereo! This chip is NOT controlled using I2C.  It is wired up to the CL-PX0001 chip and controlled from the MISC register on it.  It can switch between the external audio input and the SAA9051's audio and can also be muted.  There is a possiblity that you can read the Stereo/Mono status of the current signal from the MISC register as well.
• Philips SAA9057AT - Clock Signal Generator circuit for Digital TV systems.  Description for manual says it that 6.75 MHz input signal from SAA9051 and multiplies it to produce a 27MHz output and 2 13.5 MHz outputs.  The chip also has a "Reset control and power failure detection" that are probably not used by the Accuview design.  For general information, you can refer to its replacement part, the SAA7157 .
• Clock used: 24.576 mHz.  Probably not important since I'm assuming most clocks will come from the SAA9057.

OK, thats all the research I've done into this product.  I've probably left out a thing or two that I only have in hard copy but its a start.

There is a mailing list that was pretty active at one time. You can view the archives and perhaps talk with a few people still subscribed. It is avaliable at Yahoo Groups.

Useful Links.

Resources

• Video for Linux Resources - My personal favorite site for resources on all-things-video for Linux.  Plus, one of the first places I could get software for my Aztech Radio card.
• Color Space FAQ - Good overview of colorspace issues and some code formulas for converting for YUV to RGB.

• avtv-0.05.tar.gz - SVGAlib and X Window program that supports video capture and displaying on your screen. First program to date to fully support non-overlay mode of watching TV! Overlay mode is not supported. Can capture from RCA or TV and supports channel changing and multiple bands (uhf/catv/etc). This is the program of choice for video capture. SVGAlib version works in both 8-bit and 15-bit modes. X window version supports dynamic resize.
• Chris Pinkham - Chris has a nice X window remote control using GTK to control the xavtv program. This simulates an interface like the original Windows TV500 program. Look for and download his astv program from the above link. Chris also contributed a good deal of code to xavtv for image capture and such.
• stv500-0.7.tgz - Craig Leikis added support to the first known accuview Linux software. This version supports overlay mode and the ability to change channels and TV bands. This is the program to use if you want overlay support under a Linux console.
  • Web based CVS view of STV500 and LTV500 development software, hosted by Craig Leikis.
• xtv500-0.5.tar.gz - Steve Barbo has made the original stv500-0.5 work under Xwindows.  It is your only choice from running overlay under X windows with 8-bit depths and probably has other restrictions. It is also avaliable from ftp ://umrtv.cee.umn.edu/pub/.  You should look on his web site for the lastest version.
• xtv500-0.5.1.for-16-bit-display.tar.gz - Steve Barbo did it again. This one supports video capture and so can run under 16-bit depths in X windows. The picture will sometimes get out of sync but I bet Steve gets that working real-soon-now (tm). I suggest using avtv instead.
• tv500sdk.zip - (broken link) DOS C source code.  Appears to be diagnostic software distributed with the AccuView reference design board.
• stv500-0.5.tgz - Original Linux software for Reveal TV500 developed by Steven Karp and Gene Shaw.  Its pretty close to the tv500sdk software but with a simple SVGAlib wrapper and an incomplete Xwindow TV Tuner control.  Not of much use any more but someone might find the Xform's remote as nice example code.
• tvdos3.zip - Maxime Lapierre wrote a great DOS program for accuview based cards.  Even works as a TSR.  This is a must have if you ever run DOS although it only works in overlay mode (no screen capture). I especially like how he layed out the screen in this program and I copied it as much as possible in my savtv program.

Last Updated: August 18, 2001.
Chris Bagwell