Analog TV Out through the headphone jack ?

[benoitb]

The Nokia N900, the Galaxy S1 and several other phones from that era have an analog (PAL/NTSC) TV output that uses a cable plugged into the audio jack.

I keep my Galaxy S1 for that usage, to me it proves extremely useful in these situations:

• Multimedia enjoyment in hotels all around the world. Even if the hotel is low cost or in a third-world country, I can connect to the old TV set and watch movies, play retro games, browse youtube...
• Retro gaming looks better on a CRT TV that won't take HDMI as a video source
• Fallback for video projectors

Could it even be possible on the Pyra ? Does it require additional chips ? Am I the only one interested in this functionality ?

 

[Mirrorhead]

Another Galaxy S1 user here who thinks this would be a nice feature.

 

[Hồng Thất Công]

Oh! more ways to get video out are always good

 

[mcobit]

An analog video out would be good indeed but I don't know iftit is easy to get those connectors.

 

[Exophase]

MWeston made a thread about analog video options out which probably had some good content but it looks like it has been wiped out :/

 

[D4damage]

Analog out would be very much appreciated otherwise we'd be looking at an hdmi to composite converter box.

Sent from my Z10 using Tapatalk

 

[slaeshjag]

No current SoC has support for analogue video out, it'd need a converter chip afaik.

 

[sepulep]

in favor too...

 

[ZetaNeta]

I think that a better idea, would be a headphone jack with a support for 2 of COM and PS/2 ports each GPIO.

Just imagine how many projects may be made with that, as well as that it maybe utilized by the docking station for something.

 

[_wb_]

No current SoC has support for analogue video out, it'd need a converter chip afaik.

Would it be feasible to do this in software? E.g let a Cortex-M4 scan the screen and produce weird audio (with a very high sample rate I guess) which can be played back and correspond to an analog video signal? Would be interesting to listen to that sound

I wouldn't add an extra component for this -- if the SoC can't handle it, let it be. People can always get an active adapter cable, which is not cheap, but if you really want to use devices that only take analog input, you'll need such a cable for other devices too. The fact that such cables are not cheap probably means that it would probably add quite some cost to the Pyra to build it in.

 

[slaeshjag]

Probably not. You'd need a quite fast DAC to get acceptable results. The OMAP doesn't really have a bus suitable for one.

The OMAP does however have a digital parallel RGB out port iirc (like the one currently used to drive the pandora's LCD.)

There are chips to convert this into svideo, but they do seem to run at about €6 each in quantity.

 

[benoitb]

An analog video out would be good indeed but I don't know iftit is easy to get those connectors.

The connector is a simple 3.5mm jack with 4 poles instead of 3 for a stereo audio-only jack:

MWeston made a thread about analog video options out which probably had some good content but it looks like it has been wiped out :/

I see, if someone finds the link to that thread, I would be interested in reading it. I did a quick search on the forum before making that topic but didn't find it.

Probably not. You'd need a quite fast DAC to get acceptable results. The OMAP doesn't really have a bus suitable for one.

The OMAP does however have a digital parallel RGB out port iirc (like the one currently used to drive the pandora's LCD.)

There are chips to convert this into svideo, but they do seem to run at about €6 each in quantity.

I guess this adds too much to the cost. And svideo is nice and better quality than composite but composite is the most universal connection, always available as fallback even on the shittiest TV set. The spirit here would be to use HDMI whenever it is available and composite as fallback or for CRT retro-gaming.

Thanks to those who told their interest in this feature, at least we know this is something a few people would like to get.

 

[slaeshjag]

Composite is just Svideo with the two signal carriers mixed together.

 

[D4damage]

One of these: http://www.amazon.co.uk/gp/aw/d/B00A6STNHM/ref=pd_aw_sims_3?pi=SS115

Sent from my Z10 using Tapatalk

 

[elw3]

Would it be feasible to do this in software?

Out of interest i just checked what happens if i record and play a signal:

Spoiler

As you can see you actually get something close to a picture. Also understanding the signal is not hard at all (voltage drop for a new line, each color has its own high on the graph).

In theory it should be doable but finetuning is extremely hard similar to adjusting you satellite dish with a sledgehammer.

Not to speak what happens on the pandora, good luck turning you volume wheel with a microscope.

Would be interesting to listen to that sound

It perfectly fits in any low budget horror movie i can tell. 

Too bad that i broke my sound system with that experiment...

 

[oskarzer0]

I´m a Galaxy S1-Plus user and I think this would be a nice feature. I love the CRT TV´s.