Amiga HDMI output

[Supamax]

Ok my friends... now that I read what all you wrote I must admit I had a wrong/false information (since I was a teenager): I thought that all signal outputs from consoles/Spectrum/C64/Amiga lores modes/Dreamcast lores modes/Nintendo 64/etc. were interlaced.
Now I learned that, as you say, all those resolutions showing scan lines are the result of a progressive signal (e.g. 288p) being output from the console/microcomputer. I really didn't know .

I have a question, though. Some years ago I recorded, with a common VHS Panasonic VCR, the output from an Amiga game (lores). And it was recorded fine (I don't remember if the scan lines were visible on the video registration too, though)! Some of you said that 288p signal cannot be broadcasted without being first converted to interlaced and suffer a quality loss, but this souldn't be true since I was perfectly able to record that game (using the A520 modulator)...

Originally Posted by Mrs Beanbag

oh so those are "sideways" interlace!

Exactly .

Also, am I right if I'm saying that Amiga interlaced (hires) modes flicker so badly not only because they really are - well - interlaced, but even because the Amiga is not fast enough to produce them at the correct PAL display rate?

[Jope]

Originally Posted by Supamax

I have a question, though. Some years ago I recorded, with a common VHS Panasonic VCR, the output from an Amiga game (lores). And it was recorded fine (I don't remember if the scan lines were visible on the video registration too, though)! Some of you said that 288p signal cannot be broadcasted without being first converted to interlaced and suffer a quality loss, but this souldn't be true since I was perfectly able to record that game (using the A520 modulator)...

The video recorder just takes in each field and stores it on tape, then replays it. So it is capable of recording and playing back 288p.

Broadcast is a different story, the problem there is that most of the processors in the signal path do not accept noninterlaced signals.. The transmitter itself could probably broadcast 288p just fine, but all of the hardware in between is very fussy about getting standards compliant signals.

Also, am I right if I'm saying that Amiga interlaced (hires) modes flicker so badly not only because they really are - well - interlaced, but even because the Amiga is not fast enough to produce them at the correct PAL display rate?

No, it's not about that. The Amiga is fast enough, but the problem here is that the picture is too sharp for the technology. You can have a horizontal thin black line on only one scanline on the odd field and then a grey line on the adjacent line on the even field, where a TV frame is blurrier, the contents blend between the adjacent lines better. The slow frame rate of PAL naturally doesn't help either. NTSC is a bit better and interlaced SVGA screens were almost usable in the PC world. :-)

There were little hacks that blurred the graphics by adding some anti aliasing to the screen (and more bitplanes to your workbench) that alleviated the interlace flicker a lot at the cost of some speed and sharpness.

Commodore also made (well Philips did ;-) a high persistence monitor (the 2080) for interlace use, where the flicker wasn't as bad, but all moving objects left a trail.

[pandy71]

Originally Posted by Staringlizard

Unfortunately, after some testing and tweaking I think 720p is the limit for this hardware. The reason for stretching out the screen is not just to fill up empty space, it is simply because I do not have the time to both read and write from/to 8ns sram at the speed required (74.25Mhz reading and 28Mhz/14Mhz writing). The solution is to read pixels from sram at half rate (e.g. display each pixel twice), then I get a very manageable total maximum speed of 65,125Mhz read/write. Perhaps we will revisit the schematics and come up with something faster, still keeping the price tag down.

Just buffer/interleave R/W - should be fine - 8ns access is way above 100MHz so with proper cycling You should be able to fit in this perfectly.

And yes - output easily can be pixel doubling/quadrupling + max size is not full 1920 line period and as such you can use part of time for other thing (and mask with fixed color) - it will create some pilarbox but i believe this is unavoidable if you think about pixel perfect Amiga screen replication on modern 16:9 FHD TV's (pilarbox can be removed in TV when this mode will be selected and trough correct signaling and usually TV will provide better scaler than FPGA can have without going to expensive one, also you can use own timing but it is different case).

[strim]

I'm happy to announce that Sakura will make a batch of AMIVs!

http://sakura-it.pl/amiv.php

[ShK]

Originally Posted by strim

I'm happy to announce that Sakura will make a batch of AMIVs!

http://sakura-it.pl/amiv.php

Nice! Does 720p output have aspect ratio correction to avoid stretched image?

[brett71]

Originally Posted by strim

I'm happy to announce that Sakura will make a batch of AMIVs!

http://sakura-it.pl/amiv.php

No NTSC support? only PAL?

[strim]

Originally Posted by brett71

No NTSC support? only PAL?

We're looking into NTSC support.

Originally Posted by ShK

Nice! Does 720p output have aspect ratio correction to avoid stretched image?

By default output will fill the whole screen.

However, there will be buttons that will allow horizontal shrinking/widening of the image. Messing with this should give you the correct aspect ratio, but might lower the quality due to scaling.

We might think of dedicated emulate-4:3 mode...

[ShK]

Originally Posted by strim

We might think of dedicated emulate-4:3 mode...

Without good 4:3 mode it's like one of these: http://www.ebay.co.uk/itm/301579852663

e. Is something like this possible?

native.png
scaled.png

[Staringlizard]

Originally Posted by ShK

Without good 4:3 mode it's like one of these: http://www.ebay.co.uk/itm/301579852663

e. Is something like this possible?

native.png
scaled.png

The price is very good for the converter you mention but I have my doubts. I found one review that did not think it was very good, quite the contrary, it was the worst:
http://retrogaming.hazard-city.de/

Also, these kinds of boxes treats all input as interlaced, it means that Amiga 288p mode will have blurry movements

Anybody have this Chinese box that could enlighten us with quality?

Regards,
StaringL

[kipper2k]

I have that scart to HDMI adapter, i love it, i feed it into my Sony Bravia Multiformat TV and it gives me a sharp picture, colours are not washed out and being multiformat is good for different screen modes

[Staringlizard]

Originally Posted by pandy71

Just buffer/interleave R/W - should be fine - 8ns access is way above 100MHz so with proper cycling You should be able to fit in this perfectly.

And yes - output easily can be pixel doubling/quadrupling + max size is not full 1920 line period and as such you can use part of time for other thing (and mask with fixed color) - it will create some pilarbox but i believe this is unavoidable if you think about pixel perfect Amiga screen replication on modern 16:9 FHD TV's (pilarbox can be removed in TV when this mode will be selected and trough correct signaling and usually TV will provide better scaler than FPGA can have without going to expensive one, also you can use own timing but it is different case).

It is a little more complex. The output clock for 720p is 74.25Mhz, it means that you will need to clock some function/statemachine in FPGA that will read SRAM and that will use a multiple of this frequency. The FPGA that I am using cannot operate at multiple of 4 (297Mhz) with current implementation, only 2 (148,5Mhz) is possible, thus the granularity for the FPGA statemachine is not fine. This in combination with constraints for the SRAM when it comes to signalling makes me unable to use whole bandwidth of SRAM.

[demolition]

I have it as well and though the still picture quality is decent, it suffers some deinterlacing artifacts (even with progressive input signals) and ghosting issues as well as significant latency, making it not so good for gaming where things are moving and quick reactions are required. I would really like to have a very direct SCART RGB to HDMI conversion without frame rate conversions (synced 50Hz->50Hz), one that knows the difference between progressive and interlaced modes and only does integer scaling (unless it is a very good scaler which is not commonly seen). Some nice looking scanline emulation would be a nice bonus.

[ShK]

Originally Posted by Staringlizard

The price is very good for the converter you mention but I have my doubts. I found one review that did not think it was very good, quite the contrary, it was the worst:
http://retrogaming.hazard-city.de/

Also, these kinds of boxes treats all input as interlaced, it means that Amiga 288p mode will have blurry movements

Anybody have this Chinese box that could enlighten us with quality?

Regards,
StaringL

Actually I have that Scart to HDMI adapter too. I made you a sample video by it with PC capture card. Download video to see in full quality.

https://www.dropbox.com/s/mc97scfq79...2hdmi.mp4?dl=0

[Staringlizard]

Originally Posted by ShK

Actually I have that Scart to HDMI adapter too. I made you a sample video by it with PC capture card. Download video to see in full quality.

https://www.dropbox.com/s/mc97scfq79...2hdmi.mp4?dl=0

Thanks a lot for taking the trouble to record this !
I can see the things that the user "demolition" is talking about. But still I think it is pretty good picture actually, they did a good job. I noticed that I looked at the wrong review/box at the retrogaming review site, the box you all are talking about did get a rather good review with the price tag in mind.

When I designed AMIV I just wanted to do something by my self, basically I was bored. I did not even know these Chinese boxes existed until now

I think AMIV has a different design and approach, it is not doing any magic stuff. It just plainly takes the pixels from Amiga and puts them on the screen, no lag, no interlacing(assuming non-interlaced input), no shadows, artifacts, de-interlacing etc. Using the new board the user can connect it to a computer and even fiddle around with individual registers in the converter chain. User can even change the Verilog code for the FPGA and flash it if they would like

Regards,
StaringL

[strim]

AMIV 3.0 prototype:

[thgill]

Looking good!

Can't wait till I can order one.

[Devlin]

I want one but I have questions.

How much is it going to cost?
Will there be audio inputs?
Will it be required to plug directly into the back of the Amiga?

[strim]

Originally Posted by Devlin

I want one but I have questions.

How much is it going to cost?

The final product price is not set yet. Stay tuned for updates.

Will there be audio inputs?

No, sorry.

Will it be required to plug directly into the back of the Amiga?

It will be plugged through a short cable.

[Nostromo]

Originally Posted by voxel

why 60 Hertz ? think it's just because most of the screens (TV, Monitors, etc...) that are HDMI supports that by default... ;-) try to find a NEW monitor that is 50Hz native, saddly it are no so many now.

It is called a TV

[Devlin]

Originally Posted by strim

The final product price is not set yet. Stay tuned for updates.

No, sorry.


It will be plugged through a short cable.

Okay, I was expecting there not to be a final price, but no audio input?

By audio-input I mean a short cable that goes from the stereo connectors on Amiga to AMIV so that you can get audio through the HDMI instead of needing separate speakers.

And great to hear about it connecting via a short cable.