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assiduous
Account closed
Registered: Jun 2007
Posts: 343 |
saving the screen
hi
I seek some way to save the screen on a real C64. I need to save everything from the screen (or asmuch as possible). Im equipped with Action Replay7 and i have already tried to tamper with the freezer options but it seems that with freezing certain elements from the screen are lost like raster bars or other effects. i also tried using the backup option in AR7 which saves the executable of the frozen C64 state but that doesnt seem to save the necessary elements of the screen either (they are generated in the next frame after executing the snapshot and thats not what Im after).
thx for any help. |
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JackAsser
Registered: Jun 2002
Posts: 1989 |
It's impossible. Use a VCR connected to the c64 or something. |
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AlexC
Registered: Jan 2008
Posts: 293 |
I think that the only option is to grab a screen with hardware - use your TV card for it for example.
AR and other freeze cartridges just save memory screen, color memory, sprite data and VIC registers states (not all!). As some effects are based on timings and raster you will not see it on screen from freezer. Similar problem will be with IFLI pictures for example. So the best option is to get a frame from video output, not from c64 CPU view. |
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Mace
Registered: May 2002
Posts: 1799 |
You might want to try a PC equiped with screengrabbing interface.
That way you can digitally grab the video output of a C64.
On a real C64, like said before, it's absolutely impossible.
It can't be done, no way, it doesn't work, it won't happen. |
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Conrad
Registered: Nov 2006
Posts: 833 |
What everyone said. It's impossible to do something like this without using PC hardware and video capturing software.
The only other and inefficient way would be to take a photo of your TV close-up :) |
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assiduous
Account closed
Registered: Jun 2007
Posts: 343 |
thx for enlightement. using a tv card is no option because it saves the TV output. my TV is an LCD with a resolution of 1366x768,the C64 screen is auto stretched vertically and horizontally (with the aspect ratio kept though). i would get a stretched and blurred screen shot and what i need it for is to precisely count the number of pixels. A PAL tv would be no better in this respect.
as a matter of fact i dont need the whole screen,in 1 instance its 2 raster lines ,in the others it's just 1. but i take your word for that its not very possible and will just give up for now :) |
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ptoing
Registered: Sep 2005
Posts: 271 |
Emulator screengrab might work, no? I guess depends on the effect in some cases, but Vice is getting rather really good. |
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Jon
Account closed
Registered: Apr 2005
Posts: 247 |
I imagine a screen shot of a stretched image at 1366x768 would appear rather blocky and it'd be easier to count the pixels.
J |
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assiduous
Account closed
Registered: Jun 2007
Posts: 343 |
ptoing: VICE doesnt display the pixels i want to analyse atall. i'd grab a screen from Hoxs64 normally but the thing is that the (side-)effects i want to have a look at are not emulated correctly in any emulator (yet,some of them should be slotted in the next Hoxs64).
Ninjasbane: not really,an LCD TV performs some blurring to make a lower resolution video look better in the HD resolution,for example hires white dots every second pixel form a grey solid line ! |
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chancer
Registered: Apr 2003
Posts: 343 |
well apart from using an emulator , and perhaps snag it.. or save out as AVI without compression..
you can make/get a composite cable, and use the audio/video out on the back of the c64.. and get a usb capture device that supports composite / rgb input into ya pc.
there are a few things that do a cleaner freeze state MMC's expert cart software (AlexC I haven't forgotten..hehe)..
as you said , your doing it via HD tv? doesn't it have a vga input.. would be cleaner if you used the PC due to the refresh rate being higher in windows.
or can you adjust the tv / monitor to different modes?
I guess you could buy something to up the refresh rate so it's better suited for HD, but I'm suprised it's not backward compatible. I would go for the capture device into a pc though, you just wanna record something right?
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AlexC
Registered: Jan 2008
Posts: 293 |
Quote: well apart from using an emulator , and perhaps snag it.. or save out as AVI without compression..
you can make/get a composite cable, and use the audio/video out on the back of the c64.. and get a usb capture device that supports composite / rgb input into ya pc.
there are a few things that do a cleaner freeze state MMC's expert cart software (AlexC I haven't forgotten..hehe)..
as you said , your doing it via HD tv? doesn't it have a vga input.. would be cleaner if you used the PC due to the refresh rate being higher in windows.
or can you adjust the tv / monitor to different modes?
I guess you could buy something to up the refresh rate so it's better suited for HD, but I'm suprised it's not backward compatible. I would go for the capture device into a pc though, you just wanna record something right?
Thanks for remembering about me ;) Coming back to topic - I think this could be very good solution. If I understand it correctly the objective is to analyze some vic effect so actually recording few frames are better than just static screen shot. |
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assiduous
Account closed
Registered: Jun 2007
Posts: 343 |
thanks for all the replies.
as i said earlier using an emulator is out of the question- the effects i want to analyze dont seem to be emulated accurately in any of them.
i tried all different display modes that are available but with none of them I could get rid of scaling/blurring. if I could display it 1:1 or 2:1 without any blurring,that would do the trick but I seem unable to do so with my TV.
I dont know what you mean by the refresh rate being higher in Windows. afaik the refresh rate depends on the monitor/TV used. my TV refreshes at ~50FPS,the LCD monitor at ~60. any way i have no idea what benefit a higher refresh rate could make.
the usb capture device sounds like an idea to consider. I think that recording a few seconds of ~50 FPS video instead of just a static screen could come useful in analyzing some dynamic effects. if i understand it correctly I would get a clear digital 403x284 VIC output without any blurring distortions etc? and the fact that Im connecting this device to a 26 years old machine wouldnt really matter ? then thats something I am looking for. I would need a new cable probably- now Im using a standard 2 cinch audio-video cable. |
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assiduous
Account closed
Registered: Jun 2007
Posts: 343 |
OK done some insight. there are lots of seemingly cheap USB video capture devices. but one thing is abit worrying. The technical specifications usually say something like "25 FPS PAL". does that mean that adjacent frames would be blent into each other? :( thats not good,would disqualify it from being usable with any kind of effects that involves shifting pixels each frame. |
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JackAsser
Registered: Jun 2002
Posts: 1989 |
Quote: OK done some insight. there are lots of seemingly cheap USB video capture devices. but one thing is abit worrying. The technical specifications usually say something like "25 FPS PAL". does that mean that adjacent frames would be blent into each other? :( thats not good,would disqualify it from being usable with any kind of effects that involves shifting pixels each frame.
"clear digital 403x284 VIC output without any blurring distortions etc." will never happen... The VIC chip outputs a PAL-signal which inherently due to how PAL works WILL be blurred. I.e. chroma with half horizontal resolution than luma. To get a really clear image please try to exploit the bugs using only black and white. That would give you as much resolution as possible due to lack of chroma. |
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MagerValp
Registered: Dec 2001
Posts: 1056 |
Most capture devices "deinterlace" even progressive signals down to 25 fps, either by blurring or by weaving. Some do proper 50 fps, but it tend to be undocumented, so it's a little hit and miss...
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Radiant
Registered: Sep 2004
Posts: 639 |
MagerValp: Can you mention a device that does 50 fps? I've been thinking about getting one. |
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JackAsser
Registered: Jun 2002
Posts: 1989 |
Quote: Most capture devices "deinterlace" even progressive signals down to 25 fps, either by blurring or by weaving. Some do proper 50 fps, but it tend to be undocumented, so it's a little hit and miss...
It's indeed hit and miss. However if the device de-interlaces using weaving and the SW don't compress the result too heavily there are some hopes left. It's quite simple to extract the odd / even raster lines from a weaved frame and simply stretch the two fields to double height. This will give you back the original 50 fps progressive stream.
A problem of course if a capture device without any intelligence simply assumes the progressive stream is interlaces is first field top or not. During removal of weaving you might get temporal problems. I.e. odd lines belonging to frame x and even lines belonging to frame x+1 but you mix them up. This you'll notice immediately of course and if the capture device behaves the same always, then simply reverse field order during the process. |
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assiduous
Account closed
Registered: Jun 2007
Posts: 343 |
one of the effects involves a peculiar sideborder colour logic so black & white output wouldnt be very useful as a fact :)
theres no need for a crystal clear output,just clear enough to allow to precisely count hires pixels and verify what colour they are. I will have to find out more about devices that enable true vid capturing 50FPS progressive. |
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assiduous
Account closed
Registered: Jun 2007
Posts: 343 |
i attempted several times with various search phrases on google but i was unable to find any tv card that allows to capture a 50 FPS progressive video stream. if anyone more experienced in this field knows of such device ( MagerValp? ) then please let me know. costs dont matter. |
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MagerValp
Registered: Dec 2001
Posts: 1056 |
"50 fps" video capture yields a few good hits, including:
http://www.epixinc.com/products/pixci_sv.htm
http://www.geovision.com.tw/english/product/GV-650.htm
They don't come cheap though...
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Radiant
Registered: Sep 2004
Posts: 639 |
This thread might be interesting. I don't think those expensive cards are necessary (they seem to be aimed at a different target audience altogether).
The question is then, which cards can capture an interlaced stream without deinterlacing it? |
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JackAsser
Registered: Jun 2002
Posts: 1989 |
Quote: This thread might be interesting. I don't think those expensive cards are necessary (they seem to be aimed at a different target audience altogether).
The question is then, which cards can capture an interlaced stream without deinterlacing it?
As I said before; cards that capture in 25fps, i.e. deinterlace usually do this using the weaving method. Saving as loss-less data and then simply re-interlace shouldn't be any problems what so ever. Might take some coding effort but that's all. ;D |
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MagerValp
Registered: Dec 2001
Posts: 1056 |
Indeed, it's a software & driver problem. Since the hardware obviously grabs 50 fields per second, the problem is just getting it to output it as a progressive stream.
What about those open source drivers for BT chips?
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assiduous
Account closed
Registered: Jun 2007
Posts: 343 |
what do you mean by saving as lossless data ? the cards are usually made for capturing 50 fps interlace (or 25 fps progressive) stream,in other words they capture half of the vertical resolution of each frame because they compose each frame of 2 adjacent ones. Thats how i believe it works:
1st captured frame:
1st line: 1st C64 frame
2nd line: 2nd C64 frame
3rd line: 1st C64 frame
4th line: 2nd C64 frame
(...)
2nd captured grame:
1st line: 3rd C64 frame
2nd line: 4th C64 frame
3rd line: 3rd C64 frame
4th line: 4th C64 frame
(...)
Theres no way you can get 50 fps progressive stream in the full resolution using such cards. From the link that MagerValp posted ( http://www.epixinc.com/products/pixci_sv.htm ):
"CAPTURE OPTIONS
Capture FIELDs to Double the Capture Rate: If fast capture rate is more important than vertical resolution, then selecting the Field at Field mode doubles a field capture rate while cutting vertical resolution in half. Capture 50 fields per second from a PAL or CCIR camera; capture 60 fields per second from an NTSC or RS-170 camera."
The other link doesnt even mention if the card grabs 50 FPS interlaced or progressive so its rather likely it captures every second line.
apparently you cant do that without a hardware that captures a 50 fps progressive stream natively. if it is possible to get it to grab more vertical resolution than it specified for by using specific software/modified drivers then please post some links as I havent found anything like that |
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MagerValp
Registered: Dec 2001
Posts: 1056 |
Like I wrote earlier in the thread you'll never find it by reading documentation. You have to get a card and play with the driver settings, and if you're lucky you'll get it to capture at 50 fps progressive.
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assiduous
Account closed
Registered: Jun 2007
Posts: 343 |
finally theres a light at the end of the tunnel:) it seems that my understanding of the subject was slightly wrong- i was seeing the C64 output as 403x284 which is abit misleading. ive gained some knowledge on how PAL works and now the point of reference is 768x576. it appears that using a recording device capable of capturing half a vertical resolution at a progressive rate i could grab upto 768x288. speaking of the vertical resolution it should be actually sufficient seeing as the VIC article of Christian Bauer defines the number of visible lines as 284.
heres the post that helped me alittle to grasp the idea:
Quote:All TV's I've seen support a non-interlaced mode - a kind of 288p with a full 50Hz refresh rate if you will.
It was used extensively by older computers and video game systems. On some, such as the Atari ST or the commodore amiga you could use interlace mode and use the other 288 lines, if you wanted, at the expense of flicker (but you gained higher resolution). |
