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Forum Index : Microcontroller and PC projects : vga to avi
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stanleyella Guru  Joined: 25/06/2022 Location: United KingdomPosts: 2129 |
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| stanleyella Guru Joined: 25/06/2022 Location: United KingdomPosts: 2129 |
can this sort vga to avi? I got a few picture frames with avi input.  |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6792 |
What you've shown in the RH circuit is how the PicoMite VGA hardware works to connect the Pico to a VGA monitor. I think the LH diagram is how to get a combined video signal into a VGA monitor. Did you mean AVI or AV, which is the combined video signal? AVI is a method of packaging video files. It has nothing to do with the hardware. To watch an AVI file you need a specific codec - a piece of software running on the Pico - to unpack the file and send it out on the hardware interface. I don't think the Pico could manage that. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| stanleyella Guru Joined: 25/06/2022 Location: United KingdomPosts: 2129 |
 If I use 470r for vsync and hsync then join red,green,1/2 green,blue to hvsync after 470r and the cap to a composite video out. the avi and stereo is not standard like one lead is gnd,left,right,vid the other not. got a few of these picture frames so got to try  Edited 2024-01-08 09:04 by stanleyella |
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| Amnesie Guru Joined: 30/06/2020 Location: GermanyPosts: 396 |
AV = composite video... I already asked this question. It is not possible to have composite on the PicoMite. Only with an active converter.... |
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| stanleyella Guru Joined: 25/06/2022 Location: United KingdomPosts: 2129 |
I want to join rgb and hvsync via 470r to composite avi. I'll try and let you know what happened. |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2135 |
With custom firmware monochrome composite video is possible as Geoff's ASCII Video Terminal can do it on a PIC32MX270. At power-up it detects what is plugged in and outputs VGA or Composite as required. Colour is a far more complex beast and needs an external active converter. |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9307 |
Agreed. The VGA and Composite Video standards are totally different, and you can't just passively mix the VGA signals together and get composite video out. If you COULD, it would have been done YEARS ago, when VGA was king, and everyone used composite video based video cassette recorders etc. Even back then, to pump a computer VGA output into a TV head-end at a village or rest-home, you still needed an active converter to convert the VGA to composite video for connection to an AV modulator. Smoke makes things work. When the smoke gets out, it stops! |
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| cosmic frog Senior Member  Joined: 09/02/2012 Location: United KingdomPosts: 284 |
Many years ago I was given an old IBM PS2 system, but I didn't have a monitor for it. I was desperate to use it so I connected the Red Green and Blue output together and the Horizontal and Vertical pins together with no resistors or anything. I plugged this into the AV socket of my Ferguson Videostar video recorder which was connected to an old B/W portable TV. Amazingly I got a picture but had to mess about with the virtical hold, but the picture was very usable. I don't recommend doing this! It's a wonder I didn't damage the video card. Dave. |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6792 |
I think you need one of these Stan. The conversion is active, not passive. Note - I won't guarantee that these boxes are the answer, you need to try one. Some of the old PC video cards had "TV" (AV) output on the VGA connector so it only needed an adapter cable. I wouldn't put it past the occasional Chinese manufacturer to fail to mention that there are no actual electronics in their boxes. :) These *look* ok though as they have control buttons. I have the reverse direction version of one of these that converts AV to VGA and that works ok. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 4234 |
Stan, Don't waste any time on that solution. AV runs at 15.625kHz and is interlaced and sync is negative. VGA runs much faster (31.25kHz) and is non-interlaced and sync is positive. Best you will get is a flickering, non synchronized, black and white picture. The CMM1 has a special AV mode that will drive your AV monitor (in B/W). This is NOT implemented in CMM2 or PicoMite. Volhout Edited 2024-01-08 18:55 by Volhout PicomiteVGA PETSCII ROBOTS |
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Quazee137 Guru Joined: 07/08/2016 Location: United StatesPosts: 571 |
At one time I had access to info on a chip but its lost in storage. Something at AE  VGA 2 Comp Quazee137 Edited 2024-01-09 03:02 by Quazee137 |
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| stanleyella Guru Joined: 25/06/2022 Location: United KingdomPosts: 2129 |
I found an active circuit but the idea was having the small displays and not spending more money.  |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 9115 |
The AD724 requires the VGA signal to be both interlaced and conform to the frequency of the output required (PAL or NTSC). It is not a generic solution and definitely won't allow connection of a 640x480 standard VGA signal |
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| stanleyella Guru Joined: 25/06/2022 Location: United KingdomPosts: 2129 |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3802 |
Stan, What size screen are you using / wanting to use? Also, how much do they cost? Can't you get a VGA one that's similar in price & size? John |
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| stanleyella Guru Joined: 25/06/2022 Location: United KingdomPosts: 2129 |
Hi John, these are 7" picture frames but only sd card,usb mem, avi input. from charity shops for a few quid when they were popular. I got this 7" vga, hdmi, composite no sound for around £30 with tax and postage https://www.aliexpress.com/item/1005004670710687.html all I need is a mini ps2 keyboard but they only usb so following the usb to ps2 thread. |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3802 |
I'd stick with the aliexpress ones or if you really want to use the others maybe take one apart, figure how it works and how to use some internal signals (sounds too much hassle to me). Using an AV input sounds way too much cost & pain. John |
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| Quazee137 Guru Joined: 07/08/2016 Location: United StatesPosts: 571 |
Stan have a look at this kobolt terminominal A pico doing pal comp video with PS2 keyboard Quazee137 |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 4234 |
The ad724 chip needs 15.625 kHz VGA video. It is just a “modulator”, not a frame grabber or frame rate converter. There is no simple solution. You need to read the complete VGA screen (fast ADC’s, memory) then generate from this memory an interlaced video, then apply that to the AD724. The kobalt terminal is black and white only. Volhout Edited 2024-01-13 19:43 by Volhout PicomiteVGA PETSCII ROBOTS |
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