New video output system

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Dave
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New video output system

Postby Dave » Thu Apr 12, 2018 5:55 pm

Hi all,

While I rework the 4M RAM card to make some improvements, I have also been working on a new video output system for the QL, in light of people's problems with the original video system.

The built in RGB and UHF system is quite poor. A lot of people have problems with it.

This new system provides a new RGB output with buffered and protected lines and at the correct levels, not TTL. It is ideally suited for direct connection to video converters. It also provides a new S-Video output of high quality, and a new much improved Composite output. The S-Video system and new RGB output are of noticeably higher quality to the original outputs.

It can be configured for PAL or NTSC at build time.

It consists of two cards: one sits inside the QL and makes the new signals. The other is connected by either a short or longer IDC cable that can exit the QL either through the ROM port or the expansion port. It carries the three new video sockets.

The prototype works well on its second revision. Being much simpler and easier to test than the 4M RAM card, it will likely arrive first.

I just wanted to give a heads up so people can plan their purchases of upscalers over the next 2-3 months to take advantage of the new feature.

It will be called the Q-Vid I, because there may be a Q-Vid II that implements the novel re-timing scheme Nasta proposed a while ago.


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Re: New video output system

Postby Starfrog » Thu Apr 12, 2018 6:12 pm

Dave wrote:Hi all,

While I rework the 4M RAM card to make some improvements, I have also been working on a new video output system for the QL, in light of people's problems with the original video system.

The built in RGB and UHF system is quite poor. A lot of people have problems with it.

This new system provides a new RGB output with buffered and protected lines and at the correct levels, not TTL. It is ideally suited for direct connection to video converters. It also provides a new S-Video output of high quality, and a new much improved Composite output. The S-Video system and new RGB output are of noticeably higher quality to the original outputs.

It can be configured for PAL or NTSC at build time.

It consists of two cards: one sits inside the QL and makes the new signals. The other is connected by either a short or longer IDC cable that can exit the QL either through the ROM port or the expansion port. It carries the three new video sockets.

The prototype works well on its second revision. Being much simpler and easier to test than the 4M RAM card, it will likely arrive first.

I just wanted to give a heads up so people can plan their purchases of upscalers over the next 2-3 months to take advantage of the new feature.

It will be called the Q-Vid I, because there may be a Q-Vid II that implements the novel re-timing scheme Nasta proposed a while ago.


How does this fit inside the QL ? Does it occupy the expansion port ? And why does it need an upscaler ? Can it not take the output as a VGA connector or RGB etc ?


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Dave
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Re: New video output system

Postby Dave » Thu Apr 12, 2018 6:33 pm

It provides an 8-pin DIN RGB socket with the same pinout as the existing one on the QL, but with SCART-legal 0.7v levels instead of TTL 5v levels.

It fits in the 8301 socket, then the 8301 plugs into it.

It's designed so people who want to use a modern TV or upscaler to a modern TV have more input options to choose from, and much MUCH higher quality than the original QL's RGB or UHF system.


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Re: New video output system

Postby Starfrog » Thu Apr 12, 2018 7:15 pm

Dave wrote:It provides an 8-pin DIN RGB socket with the same pinout as the existing one on the QL, but with SCART-legal 0.7v levels instead of TTL 5v levels.

It fits in the 8301 socket, then the 8301 plugs into it.

It's designed so people who want to use a modern TV or upscaler to a modern TV have more input options to choose from, and much MUCH higher quality than the original QL's RGB or UHF system.

Oh that sounds great, so I get that install and use existing QL to Scart cable and it should be better quality ? Is there anyway you can just have it go straight to a common video connection ? Such as hdmi or dvi etc ?


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Re: New video output system

Postby martyn_hill » Thu Apr 12, 2018 8:29 pm

Great initiative Dave!

Will QVid v2 squeeze the visible scanline in to 64us to better suit the available upscalers (and PAL TV, for that matter...)?


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Re: New video output system

Postby 1024MAK » Fri Apr 13, 2018 4:10 am

Does it make use of the existing RGB video output pins of the 8301?

Mark


QL, Falcon, Atari 520STFM, Atari 1040STE, more PC's than I care to count and an assortment of 8 bit micros (Sinclair and Acorn)(nearly forgot the Psion's)
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Re: New video output system

Postby Dave » Fri Apr 13, 2018 5:20 am

martyn_hill wrote:Great initiative Dave!

Will QVid v2 squeeze the visible scanline in to 64us to better suit the available upscalers (and PAL TV, for that matter...)?


I haven't even looked at starting a MKII yet. We don't know if it would work in practice. It might work with an 8301 on an Issue 8 board with faster memory and not on an Issue 5, for example. The memory on many QLs is quite marginal already. Changing video timing changes refresh timing also.

So there MIGHT be a Mk II if it proves to work at all and be reliable across a lot of problems. I wanted to just get a basic increase of options out to people quickly and economically.


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Re: New video output system

Postby Dave » Fri Apr 13, 2018 5:25 am

1024MAK wrote:Does it make use of the existing RGB video output pins of the 8301?


Yes. It intercepts the five video signal pins at the 8301. You have a choice to also connect them to the original RGB socket, or tie the old hardware to ground. That also means you can remove the 1377 too. The main benefit of doing that is it reduces a LOT of EMI noise behind the microdrives - by about 30% on a US QL and about 60% on a UK Issue 5, if you also remove power to the modulator on the Issue 5.

Obviously, for signal quality reasons, it's better to isolate R, G and B to the new video hardware and tie the old socket pins to ground. However, the CSYNCL line is used by the (S)GC for timing purposes so I recommend that remain connected.
Last edited by Dave on Fri Apr 13, 2018 4:25 pm, edited 1 time in total.


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Re: New video output system

Postby Derek_Stewart » Fri Apr 13, 2018 9:22 am

Hi Dave,

This sounds great, the existing QL RGB is OK, but your new hardware sounds even better.

Personally, I do not use Microdrives, TV Modulator and have removed them. With the replacement of the power regulator and heat sink with a better solution the QL runs cooler with no EMI.

In future hardware addon could a VGA be integrated into the QL VIdeo system, which would allow connection to more modern monitors, I know this is not possible, but food for thought.


Regards,

Derek
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Re: New video output system

Postby Dave » Fri Apr 13, 2018 4:25 pm

Derek_Stewart wrote:Hi Dave,

This sounds great, the existing QL RGB is OK, but your new hardware sounds even better.


The quality of the output is ok, but it is an analog version of a 0 or 1 signal. Even straight RGB is analog. The signals out of the 8301 are immediately not the cleanest and do need some signal processing to clean up the edges. It's the quality of the electronics that's inadequate, in terms of the impact on the rest of the machine. The R, G, B, CSYNC and VSYNC lines traverse the entire length of the board from the expansion connector to the RGB socket. The longest track is 37.6mm long (green).13% of the PCB is consumed producing video (and 25% of the power consumption) and it's not even protected by a few zeners....

Derek_Stewart wrote:Personally, I do not use Microdrives, TV Modulator and have removed them. With the replacement of the power regulator and heat sink with a better solution the QL runs cooler with no EMI.


So you created an Issue 7.5 board - that's what I'm doing with Issue 8.[/quote]

Derek_Stewart wrote:In future hardware addon could a VGA be integrated into the QL VIdeo system, which would allow connection to more modern monitors, I know this is not possible, but food for thought.


I have looked at that. The most interesting upscaler IC ideally suited to the job is EOL. It had the amazing capability to define the front and back porch, retime everything in between before using a scaler engine to impose that onto a 720P or 1080P image, and then read out that image at 30 or 60 FPS. Of course, they discontinued that $3 IC and replaced it with a $24 IC that does the same thing in a much more integrated way. Instead of storing the config in a serial EEPROM, it runs a program on an embedded 8051 built on the die. You not only need to know the settings, but be a full 8051 programmer to create everything from the ground up - they do not provide example code.

Nasta has privately proposed a brute force FIFO-based line doubler that could be used alongside the 8301 clock manipulation trick. Our great debate was over his idea and my idea: His idea is to manipulate the clock of the 8301 between 12 MHz and 16MHz to increase the blanking time and shorten the visible area within legal limits. Place the video outputs into a pair of FIFOs and read out the first FIFO then the second FIFO. My idea is to leave the 8301 clock alone as 33% swings in the clock in a single clock cycle may upset it and the extra .5MHz memory read rate may fail inbuilt DRAM. Instead, clock the data into the line doubler FIFOs at 15MHz, and clock the data out at 24/32MHz. A small (couple of clocks) timing error may accumulate across an entire frame, so the clock could be reset as the last lines of the frame, which are black and not shown anyway. This would prevent pixel jiggling and bury the off-sync area in a non-visible part of the frame.

Now, however, Nasta has simply moved forward and found an easy way to incorporate massively improved video into a CPU card.

Besides the obvious resolution/colour depth functionality, I think it is desirable in the base modes to replace FLASH with BRITE so 4/8 colours become 8/16 colours.

I've been joking privately that soon there will be a dumpster full of (S)GCs, and that many of them will be gleaming new ones. After hearing what he proposed, my joke suddenly sounds quite realistic!

It's just the age old problem of us having destructive tendencies. Nasta can be a bit perfectionist. I tend to buy components on a whim - he'll mention there's this one component that's "very interesting" and I'll either find I have a few or buy some. I think about 20% of my components are in 'the list' and 80% are just unlogged. About half the time I have some and half the time I get some, print the data sheet, put them together (after a good read of the datasheet with a mug of coffee) and store them. This is a problem because it consumes my "hobby money".... ;)

I will be clearing a lot of components onto eBay soon. Including small quantities of every ethernet IC imaginable, and large quantities of the IC and magnetics used in the Q68. That should free up some resources ;)



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