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NTSC Video Encoding/Generation

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NTSC Video Encoding/Generation by Unknown on Jul 13, 2005			Not available!
Has anyone seen a free core for NTSC video generation (or something like a tutorial that I could at least use as a starting point)? I haven't had much luck yet, I can get a nice zigzag pattern that's supposed to be verticle lines .... Also, it seems like most of the designs or eval boards I've found online use an external NTSC encoder, typically from Phillips. Is generating color NTSC (with a parellel DAC) that hard, or is it just people being lazy? :) I did try searching the lists, but it looks like the search site still isn't returning results. Thanks, Mike Has anyone seen a free core for NTSC video generation (or something like a tutorial that I could at least use as a starting point)? I haven't had much luck yet, I can get a nice zigzag pattern that's supposed to be verticle lines .... Also, it seems like most of the designs or eval boards I've found online use an external NTSC encoder, typically from Phillips. Is generating color NTSC (with a parellel DAC) that hard, or is it just people being lazy? :) I did try searching the lists, but it looks like the search site still isn't returning results. Thanks, Mike

NTSC Video Encoding/Generation by Unknown on Jul 14, 2005			Not available!
Mike Delaney wrote: [q] Has anyone seen a free core for NTSC video generation (or something like a tutorial that I could at least use as a starting point)? I haven't had much luck yet, I can get a nice zigzag pattern that's supposed to be verticle lines ....[/q] There's a site where someone has done some NTSC generation in a PIC - I used that as a basis for my experiments with video generation at the end of last year. <<A HREF="http://www.rickard.gunee.com/projects/video/sx/howto.php">http://www.rickard.gunee.com/projects/video/sx/howto.php</A>> [q] Also, it seems like most of the designs or eval boards I've found online use an external NTSC encoder, typically from Phillips. Is generating color NTSC (with a parellel DAC) that hard, or is it just people being lazy? :)[/q] From what I understand, you need quite a high clock to give you the resolution to generate the colour information for more than a few colours. It determines how 'fast' you can change the raster colour (as it is encoded as a phase shift IIRC) and hence limits your effective horizontal resolution. You'll also need an accurate clock to generate the burst signal as displays tend to be quite fussy when it comes to locking onto the burst. Even experiments with a programmable clock didn't produce satisfactory results for me - I bought some PAL/NTSC crystal oscillators but am yet to plug them into my design... Regards, -- Mark McDougall, Software Engineer Virtual Logic Pty Ltd, <<A HREF="http://www.vl.com.au">http://www.vl.com.au</A>> 21-25 King St, Rockdale, 2216 Ph: +612-9599-3255 Fax: +612-9599-3266 Mike Delaney wrote: Has anyone seen a free core for NTSC video generation (or something like a tutorial that I could at least use as a starting point)? I haven't had much luck yet, I can get a nice zigzag pattern that's supposed to be verticle lines .... There's a site where someone has done some NTSC generation in a PIC - I used that as a basis for my experiments with video generation at the end of last year. http://www.rickard.gunee.com/projects/video/sx/howto.php> Also, it seems like most of the designs or eval boards I've found online use an external NTSC encoder, typically from Phillips. Is generating color NTSC (with a parellel DAC) that hard, or is it just people being lazy? :) From what I understand, you need quite a high clock to give you the resolution to generate the colour information for more than a few colours. It determines how 'fast' you can change the raster colour (as it is encoded as a phase shift IIRC) and hence limits your effective horizontal resolution. You'll also need an accurate clock to generate the burst signal as displays tend to be quite fussy when it comes to locking onto the burst. Even experiments with a programmable clock didn't produce satisfactory results for me - I bought some PAL/NTSC crystal oscillators but am yet to plug them into my design... Regards, -- Mark McDougall, Software Engineer Virtual Logic Pty Ltd, http://www.vl.com.au> 21-25 King St, Rockdale, 2216 Ph: +612-9599-3255 Fax: +612-9599-3266

NTSC Video Encoding/Generation by Unknown on Jul 14, 2005			Not available!
There is an NTSC composite sync generator in some code I wrote. It sounds like that's the problem you are having. Sync is a tough issue and it is not well documented. Note though that my sync in the file linked is not perfect. It is operational, but things shake a bit. I don't think I have the post-equalization phase correct right now. It works on several tvs though. As for generating color, that's a bit trickier, though not impossible. I have been considering developing a color generator, but I haven't gotten to it yet. For the project below, I had a standalone color encoder. I just had to give it the three colors (rgb in this case) and the composite sync and it took care of the color for me. <A HREF="http://www1.pacific.edu/~a-cox/SeniorProject/graphics.rar">http://www1.pacific.edu/~a-cox/SeniorProject/graphics.rar</A> You may use my code as you will, but I cannot support it. -Arlen On 7/13/05, Mark McDougall <<A HREF="http://www.opencores.org/mailman/listinfo/cores">markm at vl.com.au</A>> wrote: [q] Mike Delaney wrote: [q]> Has anyone seen a free core for NTSC video generation (or something > like a tutorial that I could at least use as a starting point)? I > haven't had much luck yet, I can get a nice zigzag pattern that's > supposed to be verticle lines ....[/q] There's a site where someone has done some NTSC generation in a PIC - I used that as a basis for my experiments with video generation at the end of last year. <<A HREF="http://www.rickard.gunee.com/projects/video/sx/howto.php">http://www.rickard.gunee.com/projects/video/sx/howto.php</A>> [q]> Also, it seems like most of the designs or eval boards I've found > online use an external NTSC encoder, typically from Phillips. Is > generating color NTSC (with a parellel DAC) that hard, or is it just > people being lazy? :)[/q] From what I understand, you need quite a high clock to give you the resolution to generate the colour information for more than a few colours. It determines how 'fast' you can change the raster colour (as it is encoded as a phase shift IIRC) and hence limits your effective horizontal resolution. You'll also need an accurate clock to generate the burst signal as displays tend to be quite fussy when it comes to locking onto the burst. Even experiments with a programmable clock didn't produce satisfactory results for me - I bought some PAL/NTSC crystal oscillators but am yet to plug them into my design... Regards, -- Mark McDougall, Software Engineer Virtual Logic Pty Ltd, <<A HREF="http://www.vl.com.au">http://www.vl.com.au</A>> 21-25 King St, Rockdale, 2216 Ph: +612-9599-3255 Fax: +612-9599-3266 _______________________________________________ <A HREF="http://www.opencores.org/mailman/listinfo/cores">http://www.opencores.org/mailman/listinfo/cores</A> [/q] There is an NTSC composite sync generator in some code I wrote. It sounds like that's the problem you are having. Sync is a tough issue and it is not well documented. Note though that my sync in the file linked is not perfect. It is operational, but things shake a bit. I don't think I have the post-equalization phase correct right now. It works on several tvs though. As for generating color, that's a bit trickier, though not impossible. I have been considering developing a color generator, but I haven't gotten to it yet. For the project below, I had a standalone color encoder. I just had to give it the three colors (rgb in this case) and the composite sync and it took care of the color for me. http://www1.pacific.edu/~a-cox/SeniorProject/graphics.rar You may use my code as you will, but I cannot support it. -Arlen On 7/13/05, Mark McDougall markm at vl.com.au> wrote: Mike Delaney wrote: > Has anyone seen a free core for NTSC video generation (or something > like a tutorial that I could at least use as a starting point)? I > haven't had much luck yet, I can get a nice zigzag pattern that's > supposed to be verticle lines .... There's a site where someone has done some NTSC generation in a PIC - I used that as a basis for my experiments with video generation at the end of last year. http://www.rickard.gunee.com/projects/video/sx/howto.php> > Also, it seems like most of the designs or eval boards I've found > online use an external NTSC encoder, typically from Phillips. Is > generating color NTSC (with a parellel DAC) that hard, or is it just > people being lazy? :) From what I understand, you need quite a high clock to give you the resolution to generate the colour information for more than a few colours. It determines how 'fast' you can change the raster colour (as it is encoded as a phase shift IIRC) and hence limits your effective horizontal resolution. You'll also need an accurate clock to generate the burst signal as displays tend to be quite fussy when it comes to locking onto the burst. Even experiments with a programmable clock didn't produce satisfactory results for me - I bought some PAL/NTSC crystal oscillators but am yet to plug them into my design... Regards, -- Mark McDougall, Software Engineer Virtual Logic Pty Ltd, http://www.vl.com.au> 21-25 King St, Rockdale, 2216 Ph: +612-9599-3255 Fax: +612-9599-3266 _______________________________________________ http://www.opencores.org/mailman/listinfo/cores

NTSC Video Encoding/Generation by Unknown on Jul 15, 2005			Not available!
Hey Mike, Until you get the NTSC video signal generating down you can get simple converters (analog)RGB+HSYNC+VSYNC to NTSC like AD724? There are other chips but you'll have to do a websearch. Best of all the AD724 can generate S-Video for a better picture. Download the datasheet from analog devices and you get get an idea of what is involved in RGB to NTSC video. Aaron ----- Original Message ----- From: Mike Delaney<<A HREF="http://www.opencores.org/mailman/listinfo/cores">mmdst23 at g...</A>> To: Date: Wed Jul 13 23:51:15 CEST 2005 Subject: [oc] NTSC Video Encoding/Generation [q] Has anyone seen a free core for NTSC video generation (or something like a tutorial that I could at least use as a starting point)? I haven't had much luck yet, I can get a nice zigzag pattern that's supposed to be verticle lines .... Also, it seems like most of the designs or eval boards I've found online use an external NTSC encoder, typically from Phillips. Is generating color NTSC (with a parellel DAC) that hard, or is it just people being lazy? :) I did try searching the lists, but it looks like the search site still isn't returning results. Thanks, Mike [/q] Hey Mike, Until you get the NTSC video signal generating down you can get simple converters (analog)RGB+HSYNC+VSYNC to NTSC like AD724? There are other chips but you'll have to do a websearch. Best of all the AD724 can generate S-Video for a better picture. Download the datasheet from analog devices and you get get an idea of what is involved in RGB to NTSC video. Aaron ----- Original Message ----- From: Mike Delaneymmdst23 at g...> To: Date: Wed Jul 13 23:51:15 CEST 2005 Subject: [oc] NTSC Video Encoding/Generation Has anyone seen a free core for NTSC video generation (or something like a tutorial that I could at least use as a starting point)? I haven't had much luck yet, I can get a nice zigzag pattern that's supposed to be verticle lines .... Also, it seems like most of the designs or eval boards I've found online use an external NTSC encoder, typically from Phillips. Is generating color NTSC (with a parellel DAC) that hard, or is it just people being lazy? :) I did try searching the lists, but it looks like the search site still isn't returning results. Thanks, Mike

NTSC Video Encoding/Generation by Unknown on Jul 15, 2005			Not available!
Thanks to everyone who'se replied. I'm under a lot of contraints on this project, it looks like the end design will (hopefully, assuming I can get it working right :) use a Phillips chip that'll take non-interlaced YCrCb and give me composite NTSC out. For now, just trying to get the other end working while I'm waiting on samples, I'm going to use VGA and a AD724 (or one of their other two). It dosen't look like getting NTSC working in full color from an FPGA is worth the effort for this design. Mike On 7/14/05, <A HREF="http://www.opencores.org/mailman/listinfo/cores">aecohen69 at hotmail.com</A> <<A HREF="http://www.opencores.org/mailman/listinfo/cores">aecohen69 at hotmail.com</A>> wrote: [q] Hey Mike, Until you get the NTSC video signal generating down you can get simple converters (analog)RGB+HSYNC+VSYNC to NTSC like AD724? There are other chips but you'll have to do a websearch. Best of all the AD724 can generate S-Video for a better picture. Download the datasheet from analog devices and you get get an idea of what is involved in RGB to NTSC video. Aaron ----- Original Message ----- From: Mike Delaney<<A HREF="http://www.opencores.org/mailman/listinfo/cores">mmdst23 at g...</A>> To: Date: Wed Jul 13 23:51:15 CEST 2005 Subject: [oc] NTSC Video Encoding/Generation [q]> Has anyone seen a free core for NTSC video generation (or something > like a tutorial that I could at least use as a starting point)? I > haven't had much luck yet, I can get a nice zigzag pattern that's > supposed to be verticle lines .... > Also, it seems like most of the designs or eval boards I've found > online use an external NTSC encoder, typically from Phillips. Is > generating color NTSC (with a parellel DAC) that hard, or is it > just > people being lazy? :) > I did try searching the lists, but it looks like the search site > still > isn't returning results. > Thanks, > Mike > >[/q] _______________________________________________ <A HREF="http://www.opencores.org/mailman/listinfo/cores">http://www.opencores.org/mailman/listinfo/cores</A> [/q] Thanks to everyone who'se replied. I'm under a lot of contraints on this project, it looks like the end design will (hopefully, assuming I can get it working right :) use a Phillips chip that'll take non-interlaced YCrCb and give me composite NTSC out. For now, just trying to get the other end working while I'm waiting on samples, I'm going to use VGA and a AD724 (or one of their other two). It dosen't look like getting NTSC working in full color from an FPGA is worth the effort for this design. Mike On 7/14/05, aecohen69 at hotmail.com aecohen69 at hotmail.com> wrote: Hey Mike, Until you get the NTSC video signal generating down you can get simple converters (analog)RGB+HSYNC+VSYNC to NTSC like AD724? There are other chips but you'll have to do a websearch. Best of all the AD724 can generate S-Video for a better picture. Download the datasheet from analog devices and you get get an idea of what is involved in RGB to NTSC video. Aaron ----- Original Message ----- From: Mike Delaneymmdst23 at g...> To: Date: Wed Jul 13 23:51:15 CEST 2005 Subject: [oc] NTSC Video Encoding/Generation > Has anyone seen a free core for NTSC video generation (or something > like a tutorial that I could at least use as a starting point)? I > haven't had much luck yet, I can get a nice zigzag pattern that's > supposed to be verticle lines .... > Also, it seems like most of the designs or eval boards I've found > online use an external NTSC encoder, typically from Phillips. Is > generating color NTSC (with a parellel DAC) that hard, or is it > just > people being lazy? :) > I did try searching the lists, but it looks like the search site > still > isn't returning results. > Thanks, > Mike > > _______________________________________________ http://www.opencores.org/mailman/listinfo/cores

NTSC Video Encoding/Generation by Unknown on Jul 20, 2005			Not available!
[q] From what I understand, you need quite a high clock to give you the resolution to generate the colour information for more than a few colours.[/q] It does not need to be very high but best results and simplicity do require that the reference clock be an exact multiple of the color burst frequency. Yes, color information is encoded as a phase shift between color burst and chroma. For reasonably accurate phase generation, oversampling needs to be at least 4X, preferably 6X. With a color burst of 3.569545MHz, a clock rate of 21.41727MHz or 28.55636MHz would be ideal, extra temporal resolution should be attainable by using the FPGA's DCM/PLL/etc. facilities but would most likely turn out to be overkill. Black&White is relatively simple, the only particularly touchy things are horizontal and vertical blanking intervals. For color though, the phase-amplitude coding using CrCb data is somewhat tricky. To generate the chroma signal, the CrCb vector's angle and magnitude are needed, both could be obtained from a lookup table, with the angle being expressed as a sin table offset. To generate the chroma signal, all that is needed then is to do Amplitude * sin[n + Offset], the rest from here is mostly trivial. From what I understand, you need quite a high clock to give you the resolution to generate the colour information for more than a few colours. It does not need to be very high but best results and simplicity do require that the reference clock be an exact multiple of the color burst frequency. Yes, color information is encoded as a phase shift between color burst and chroma. For reasonably accurate phase generation, oversampling needs to be at least 4X, preferably 6X. With a color burst of 3.569545MHz, a clock rate of 21.41727MHz or 28.55636MHz would be ideal, extra temporal resolution should be attainable by using the FPGA's DCM/PLL/etc. facilities but would most likely turn out to be overkill. Black&White is relatively simple, the only particularly touchy things are horizontal and vertical blanking intervals. For color though, the phase-amplitude coding using CrCb data is somewhat tricky. To generate the chroma signal, the CrCb vector's angle and magnitude are needed, both could be obtained from a lookup table, with the angle being expressed as a sin table offset. To generate the chroma signal, all that is needed then is to do Amplitude * sin[n + Offset], the rest from here is mostly trivial.

NTSC Video Encoding/Generation by Unknown on Jul 21, 2005			Not available!
I hacked up a simple one here www.geocities.com/wv9557 ----- Original Message ----- From: Mike Delaney<<A HREF="http://www.opencores.org/mailman/listinfo/cores">mmdst23 at g...</A>> To: Date: Wed Jul 13 23:51:15 CEST 2005 Subject: [oc] NTSC Video Encoding/Generation [q] Has anyone seen a free core for NTSC video generation (or something like a tutorial that I could at least use as a starting point)? I haven't had much luck yet, I can get a nice zigzag pattern that's supposed to be verticle lines .... Also, it seems like most of the designs or eval boards I've found online use an external NTSC encoder, typically from Phillips. Is generating color NTSC (with a parellel DAC) that hard, or is it just people being lazy? :) I did try searching the lists, but it looks like the search site still isn't returning results. Thanks, Mike [/q] I hacked up a simple one here www.geocities.com/wv9557 ----- Original Message ----- From: Mike Delaneymmdst23 at g...> To: Date: Wed Jul 13 23:51:15 CEST 2005 Subject: [oc] NTSC Video Encoding/Generation Has anyone seen a free core for NTSC video generation (or something like a tutorial that I could at least use as a starting point)? I haven't had much luck yet, I can get a nice zigzag pattern that's supposed to be verticle lines .... Also, it seems like most of the designs or eval boards I've found online use an external NTSC encoder, typically from Phillips. Is generating color NTSC (with a parellel DAC) that hard, or is it just people being lazy? :) I did try searching the lists, but it looks like the search site still isn't returning results. Thanks, Mike

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