Internal HDMI output from an A8 using existing video signals

[+x=usr(1536)]

While looking into ICs for something unrelated, I ran across the Analog Devices ADV7850 (datasheet attached).  This chip looks to have been primarily designed with switching multiple inputs to a single output in mind, but has features that may be of interest for A8 video output.

 

The chip has inputs for both Y/C (luma / chroma, aka S-Video) and composite video as well as audio.  Digital encoding of the analogue signals is performed on the chip itself with no preprocessing needed provided that signal levels are within the spec the chip expects.

 

This has me wondering if it couldn't be used in conjunction with the A8's existing Y/C output (or Y/C from a UAV or similar) to provide onboard HDMI output.  This could conceivably make it a single-board solution, similar to the UAV.

 

In machines without on-board Y/C signals (2600, 5200, 7800) either their existing composite signals could be used (it has a comb filter to separate Y/C from a composite signal), or this IC could be daisy-chained with a UAV in order to pull Y/C directly to it.

 

Not going to be building a prototype anytime soon that uses this, but am interested to hear any thoughts on the subject.

ADV7850.pdf

[Rybags]

Just a quick look, but going on experience with video capture and consumer recording devices etc in the past.

Sometimes they don't like the non interlaced slightly non standard signal from old computers.

Sometimes you get a resultant picture that is frame blended with each subsequent frame treated as odd/even interlaced fields.

In some cases there's options to overcome such things.

In some cases it's just a bit of a turd sandwich and you have to use something else.

 

Evidence of how it might work could be gotten if you could find an existing device that uses the IC.

Bottom line though - the picture quality probably wouldn't have huge advantage over existing external video converters, though an inbuilt device that involves modifying the computer and taking video feeds further up the line in theory should give it a bit of an edge at the least.

[+x=usr(1536)]

29 minutes ago, Rybags said:

Just a quick look, but going on experience with video capture and consumer recording devices etc in the past.

Sometimes they don't like the non interlaced slightly non standard signal from old computers.

Sometimes you get a resultant picture that is frame blended with each subsequent frame treated as odd/even interlaced fields.

In some cases there's options to overcome such things.

In some cases it's just a bit of a turd sandwich and you have to use something else.

 

Evidence of how it might work could be gotten if you could find an existing device that uses the IC.

All of which makes sense.  FWIW, the expectation isn't so much that it would generate the absolute best video output, but rather that it would give really good video that's consistently reproducible from device to device.  Still, points taken, especially re: finding a device using the chip in order to get a feel for the video quality.

29 minutes ago, Rybags said:

Bottom line though - the picture quality probably wouldn't have huge advantage over existing external video converters, though an inbuilt device that involves modifying the computer and taking video feeds further up the line in theory should give it a bit of an edge at the least.

This is pretty much my thinking: it would be fairly close to the UAV or Spectre in terms of internal modification, but with HDMI output.  Where its value looks to be is in the possibility of a single-board internal HDMI solution as well as making the need for Y/C or Composite signals generated from a separate board entirely optional (in an A8, at least).

 

One thing I'll note is that while I didn't poke around extensively, I wasn't having much luck finding anything equivalent in the single-chip-solution department.  There is one chip (Panasonic MN864729) used in some versions of the PS4 that may be an option, but given that it went into a Sony product the datasheet isn't really floating around so can't confirm that.