Post by thread:Video overlay for PIC?

Not quite a direct PIC question, but wondered if anyone had interfaced any device(s) to generate a video text overlay over either NTSC or PAL video? I believe Philips has some IC2 devices to do this, but wondered if there was any "real world" experince on this list? Specificially, I'm just looking to display simple text (doesn't need to be anti-aliased) over top of video. Of course, it would need to be in sync with the underlying video signal. Thanks Regards, ------------------------------------ | Jeff King Aero Data Systems | | spam_OUTjeffTakeThisOuTmich.com P.O. Box 510895 | | (810)471-1787 Livonia, MI 48151 | |F(810)471-0279 United States | ------------------------------------

Jeff King wrote: {Quote hidden}> > Not quite a direct PIC question, but wondered if anyone had > interfaced any device(s) to generate a video text overlay > over either NTSC or PAL video? I believe Philips has some > IC2 devices to do this, but wondered if there was any "real > world" experince on this list? > > Specificially, I'm just looking to display simple text (doesn't > need to be anti-aliased) over top of video. Of course, it would > need to be in sync with the underlying video signal. > > Thanks > > Regards, > > ------------------------------------ > | Jeff King Aero Data Systems | > | .....jeffKILLspam@spam@mich.com P.O. Box 510895 | > | (810)471-1787 Livonia, MI 48151 | > |F(810)471-0279 United States | > ------------------------------------ I already saw a project like this, I think its on David Taits pic stuff page. I was a clock that displayed time on the TV screen. Hope this helps. -- _____________ \ / David BALDWIN \ ALCATEL / Design engineer \TELECOM/ \ / SdM (Societe de Microelectronique) \ / \ / B.P. 4205 Phone : +32 (0)71 442932 V B-6000 Charleroi Fax : +32 (0)71 442905 (Belgium) baldwinKILLspametca.alcatel.be

Mike wrote: > > > I was a clock that displayed time on the TV screen. > > You mean there was a video of you with your hands in various positions > showing the hands of a clock ? > > (Sorry couldn't resist it :))) > > Rgds > > Mike > > Some say there is no magic but, all things begin with thought then it becomes > academic, then some poor slob works out a practical way to implement all that > theory, this is called Engineering - for most people another form of magic. > Massen Not bad, not bad.... :) -- _____________ \ / David BALDWIN \ ALCATEL / Design engineer \TELECOM/ \ / SdM (Societe de Microelectronique) \ / \ / B.P. 4205 Phone : +32 (0)71 442932 V B-6000 Charleroi Fax : +32 (0)71 442905 (Belgium) .....baldwinKILLspam.....etca.alcatel.be

> > Not quite a direct PIC question, but wondered if anyone had > interfaced any device(s) to generate a video text overlay > over either NTSC or PAL video? I believe Philips has some > IC2 devices to do this, but wondered if there was any "real > world" experince on this list? > > Specificially, I'm just looking to display simple text (doesn't > need to be anti-aliased) over top of video. Of course, it would > need to be in sync with the underlying video signal. Go take a read around the http://www.circellar.com web site. There was a design contest winner that had a wind speed indicator with video output that used a single PIC. It probably could be adapted to your overlay project with the use of a sync detector. In a nutshell: 1) Use the sync detector to detect starts of frames and lines. 2) Use a analog switch that will pass either the regular video or pure white. 3) Program the PIC to switch the switch at appropriate times. I've never done this, as I'm not a video guy, but I think the basic concept is sound. Hope this helps, BAJ

>1) Use the sync detector to detect starts of frames and lines. >2) Use a analog switch that will pass either the regular video or > pure white. >3) Program the PIC to switch the switch at appropriate times. > >I've never done this, as I'm not a video guy, but I think the basic >concept is sound. I've done this. One more point: 4) Run the PIC synchronous to the horizontal clock rate. Andy ====================================================================== Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865 USA Electronics for Industry & R/C Hobbyists "Go fast, turn right, and keep the wet side down!" ======================================================================

Hi: My PIC will be doing other things, so I'd like it to be off board. Overlay (i.e. being able to insert text into a pre- existing video signal) is a requirement. The 'chips' I am refering to are in many (most) TV's today... the type that can overlay closed captioning or various TV functions (like your volume setting and channel). All the various functions (sync seperation etc) are already done for you. Generally you talk to them via a IC2 line. What I am asking is if anyone has used any of these with PIC's and what there experince's were. As this is not a specific PIC question, I might be best asking this on sci.electronics. But since my target processor is a PIC, I thought I'd start here :-) Thanks! Regards, ------------------------------------ | Jeff King Aero Data Systems | | EraseMEjeffspam_OUTTakeThisOuTmich.com P.O. Box 510895 | | (810)471-1787 Livonia, MI 48151 | |F(810)471-0279 United States | ------------------------------------

I've used several types of OSD (on screen display) chips in the past. For a while the most common types were Fujitsu MB88323 ,88325 and Mitsubishi M50554 ect. I still have documentation for these types and probably have some parts floating around. These are fairly easy devices to use and have SPI interfacing to a micro. They offer up to 12 lines of 24 character text. Overlay is possible in monochrome. If you want to discuss it more send me some e-mail directly. Regards. At 11:25 AM 3/5/97 -0500, you wrote: {Quote hidden}>Hi: > >My PIC will be doing other things, so I'd like it to be off >board. Overlay (i.e. being able to insert text into a pre- >existing video signal) is a requirement. > >The 'chips' I am refering to are in many (most) TV's today... >the type that can overlay closed captioning or various TV >functions (like your volume setting and channel). All >the various functions (sync seperation etc) are already >done for you. Generally you talk to them via a IC2 line. > >What I am asking is if anyone has used any of these with >PIC's and what there experince's were. As this is not >a specific PIC question, I might be best asking this on >sci.electronics. But since my target processor is a PIC, >I thought I'd start here :-) > >Thanks! > >Regards, > >------------------------------------ >| Jeff King Aero Data Systems | >| jeffspam_OUTmich.com P.O. Box 510895 | >| (810)471-1787 Livonia, MI 48151 | >|F(810)471-0279 United States | >------------------------------------ > > ****************************** Richard Katezansky Tangent Electronics Ltd. Montreal, Canada ******************************

Jeff King <@spam@jeffKILLspamMICH.COM> wrote: > Not quite a direct PIC question, but wondered if anyone had > interfaced any device(s) to generate a video text overlay > over either NTSC or PAL video? I believe Philips has some > IC2 devices to do this, but wondered if there was any "real > world" experince on this list? > > Specificially, I'm just looking to display simple text (doesn't > need to be anti-aliased) over top of video. Of course, it would > need to be in sync with the underlying video signal. Byron A Jeff <KILLspambyronKILLspamCC.GATECH.EDU> replied: > Go take a read around the http://www.circellar.com web site. There was a design > contest winner that had a wind speed indicator with video output that used > a single PIC. It probably could be adapted to your overlay project with > the use of a sync detector. In a nutshell: > > 1) Use the sync detector to detect starts of frames and lines. > 2) Use a analog switch that will pass either the regular video or > pure white. > 3) Program the PIC to switch the switch at appropriate times. What you will find is that there is an unacceptable amount of jitter in the horizontal positioning of your overlaid video. Generally the tightest synchronization you can get to the horizontal sync will be two PIC instructions, or perhaps one instruction using some hardware-dependent tricks. If the PIC is running at 20 MHz, that's 200 or 400 nS. If you really want to use a PIC to generate a video overlay, you need to use a PLL to generate a master clock for the PIC that is a phase-locked multiple of the horizontal sync. In general it is much easier to use the video overlay chips that are designed for this purpose. Also, they can generate better looking characters; the PIC can't provide very good horizontal resolution. But for specialized applications, using the PIC and PLL approach may be useful. That's how my closed-caption *encoder* works. Cheers, Eric

In message <RemoveME2.2.32.19970305162557.006ab3b0TakeThisOuTmail.mich.com>> spamBeGonePICLISTspamBeGoneMITVMA.MIT.EDU writes: Hi, > My PIC will be doing other things, so I'd like it to be off > board. Overlay (i.e. being able to insert text into a pre- > existing video signal) is a requirement. > > The 'chips' I am refering to are in many (most) TV's today... > the type that can overlay closed captioning or various TV > functions (like your volume setting and channel). All > the various functions (sync seperation etc) are already > done for you. Generally you talk to them via a IC2 line. This requirement disposes of most of the TV chips used for OSD, they normally produce an RGB signal that is fed directly to the CRT cathode drivers. They are not able to add text to a comnposite video signal. The type of chip you require is that used for OSD in VCR's and satellite receivers, they genlock text on top of an existing composite video signal. > What I am asking is if anyone has used any of these with > PIC's and what there experince's were. As this is not > a specific PIC question, I might be best asking this on > sci.electronics. But since my target processor is a PIC, > I thought I'd start here :-) The main problem is finding data sheets for the video chips, I tried to find them for chips from Sharp, Mitsubishi and NEC. The only datasheet I was able to obtain was from NEC for the uPD6450, this will display 12x24 characters on top of an existing composite signal. In the UK it is used in a number of Hitachi VCR's and Amstrad satellite receivers. I currently have PIC (16C84) code for controlling the uPD6450, it can either superimpose text over a composite signal, or display on a coloured background - this is usually used in VCR's when there is no signal available, most often defaults to a 'blue mute' screen provided by the display chip. If you would like the code, feel free to ask, although It's not finished yet, it does feed the display chip quite nicely!. Nigel. /--------------------------------------------------------------\ | Nigel Goodwin | Internet : TakeThisOuTnigelgEraseMEspam_OUTlpilsley.demon.co.uk | | Lower Pilsley | Web Page : http://www.lpilsley.demon.co.uk | | Chesterfield | | | England | | \--------------------------------------------------------------/

Jeff King wrote: Hi: My PIC will be doing other things, so I'd like it to be off board. Overlay (i.e. being able to insert text into a pre- existing video signal) is a requirement. The 'chips' I am refering to are in many (most) TV's today... the type that can overlay closed captioning or various TV functions (like your volume setting and channel). All the various functions (sync seperation etc) are already done for you. Generally you talk to them via a IC2 line. What I am asking is if anyone has used any of these with PIC's and what there experince's were. As this is not a specific PIC question, I might be best asking this on sci.electronics. But since my target processor is a PIC, I thought I'd start here :-) Thanks! Regards, ------------------------------------ | Jeff King Aero Data Systems | | RemoveMEjeffTakeThisOuTmich.com P.O. Box 510895 | | (810)471-1787 Livonia, MI 48151 | |F(810)471-0279 United States | ------------------------------------ Take a look at the uPD6450 family from NEC. They have a simple 3-wire interface, very easy to handle in SW. Sync separation has to be made separately though. LM1881 is the basic choice. Goeran Moerk gmEraseME.....sysinno.se

>Hi Jeff, > >Jeff King schrieb an Dm: > > JK> The 'chips' I am refering to are in many (most) TV's today... > JK> done for you. Generally you talk to them via a IC2 line. > >What are these chips and can they display (changeable) text in various >positions of the tv-screen (pal) ? > >cu Dieter >... Mama, 's Guido packt aus! > > I know one of these chips is TC9020P (should be Toshiba's product). I have its diagram but don't know how to program it. Actually I am searching for the necessary infomation to use it. Does any one know?