dbwithlemon
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RCA Video Quality

Tue Mar 03, 2015 4:45 pm

I just had a general question. I recently set up my Raspberry Pi.
It's connected to my TV and it will be used for some specific internet browsing. No video or anything, primarily filling out forms and data entry.
Currently it's using an HDMI port, but I want to switch it to an RCA cable. I've heard the video quality with the RCA setup isn't very good, but don't have any frame of reference for how bad it will be.

Does anyone have any screenshots, or advice if the cable will be sufficient to read things clearly and easily?

Thanks

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Re: RCA Video Quality

Tue Mar 03, 2015 5:16 pm

Worse than HDMI is about the only metric that makes sense. It really a try it and see type of thing.
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Re: RCA Video Quality

Tue Mar 03, 2015 5:37 pm

The only useful thing I've done with analog video is running the Teletext system on the RPi and decoding it on my TV. That gets nice sharp graphics, even though Teletext is a bit clunky.
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Re: RCA Video Quality

Tue Mar 03, 2015 6:12 pm

dbwithlemon wrote: I've heard the video quality with the RCA setup isn't very good, but don't have any frame of reference for how bad it will be.
This does depend somewhat on which video standard you use (NTSC or PAL). Being from the US, I know NTSC; PAL should *probably* be a smidge better with good hardware.

In general terms, you should get 480i class performance. With a good video monitor and cable, and assuming the Pi does things properly, you should be able to get decent 640x480, which is enough to display an 80-character, 24 or 25 line terminal window and do real work on the command line. (People certainly managed back in the 80's.)

However, this isn't always the case; there are reasons that back in the day people using PCs plugged into ordinary home TVs frequently only ran 40-character screens, because the usable resolution for things with sharp edges like text was about half the theoretical. (This sort of thing used to be the primary distinction between a "video monitor" and a "television", along with a monitor not necessarily having an over-the-air tuner built in.)

Now, modern TVs are so much better than from decades ago this should be a non-issue. But it turns out that old-school RCA input is so depreciated in some areas that some TVs do a surprisingly bad job of scaling it, since basically no one cared to do better.

Some real world thoughts: Anything a Pi 1 can emulate at full speed (generally, 4th-gen consoles) should look fine, as they were intended for those sorts of TVs in the first place. The Pi 2 is starting to get into PS1 (5th-gen console) emulation territory; games in that era were still designed to be usable on NTSC, but some may not look quite as good as they theoretically can. You will certainly be able to use a 40x12 terminal, and probably a 80x24 one. Using X11 for anything but the simplest tasks will be painful; among other things, many menu screens assume you have at least 800x600 available. The Pi is *usable* down to at least a 3" diagonal, NTSC input, 320x200 car-mount screen, but neither practical to do much serious work nor a lot of fun *as a PC* at those resolutions. (It's awesome as an embedded system still, of course.)

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Re: RCA Video Quality

Tue Mar 03, 2015 6:20 pm

Here is a photo of a 7" LCD display. http://home.budget.net/~klricks/Comp/RP ... posit.html
Note this is NTSC (US). Pal (UK) output may be a bit better.
The terminal font was enlarged from default and the output looks better in photo than real life. The pixels of text and static images do jitter.
LCD screens seem to be better than old CRT screens... gives me a headache.
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dbwithlemon
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Re: RCA Video Quality

Tue Mar 03, 2015 8:59 pm

Thanks to everyone for the reply, I guess I'll have to stick with HDMI and maybe get an HDMI-DVI converter.

It's running on a 42" NTSC TV, so the text being readable from a distance matters.

ray.leiter
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Re: RCA Video Quality

Tue Mar 03, 2015 9:59 pm

I was looking through the posts and saw yours and thought I'd comment.
You will be ok using an RCA (composite video connection)!
That was all many of us had we we began.
I tried the RCA connection from my Rpi B+ to my Panasonic 40 inch plasma TV and it was very good.
Of course it isn't the quality of HDMI, but since you are only interested in data entry into forms, you will have no problem.
The quality of your image will also depend on the TV you use (size, etc.).
It will be more than adequate for your purposes.
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Re: RCA Video Quality

Tue Mar 03, 2015 10:07 pm

dbwithlemon wrote:Thanks to everyone for the reply, I guess I'll have to stick with HDMI and maybe get an HDMI-DVI converter.

It's running on a 42" NTSC TV, so the text being readable from a distance matters.
I wonder if you might want to consider an HDMI to VGA converter instead of HDMI to DVI?
Many TVs can handle VGA and most monitors can accept VGA rather than DVI.
If you do opt for an HDMI to DVI/VGA converter, consider whether the converter will provide access via a 3.5 mm jack to the audio that will be present on the HDMI connection from the Pi.

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Re: RCA Video Quality

Tue Mar 03, 2015 10:11 pm

dbwithlemon wrote:Thanks to everyone for the reply, I guess I'll have to stick with HDMI and maybe get an HDMI-DVI converter.
HDMI to DVI-D is a simple straight cable with an HDMI connector on one end and a DVI-D on the other, costs a fiver. No converters for DVI-D needed, it is HDMI with a different pinout.
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ray.leiter
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Re: RCA Video Quality

Tue Mar 03, 2015 10:24 pm

Does DVI include audio as does HDMI?

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Re: RCA Video Quality

Tue Mar 03, 2015 11:14 pm

ray.leiter wrote:Does DVI include audio as does HDMI?
Nope. That's the new piece when they reengineered DVI-D. That's the difference between CEA and DMT modes.
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Re: RCA Video Quality

Wed Mar 04, 2015 2:59 pm

For my purposes I won't need audio.
It's for a specific function, mostly data entry in a browser. But it needs to be clear enough to read from across the room on the TV.
The problem is my TV only has 2 HDMI ports and they're both claimed. My TV doesn't have DVI either, but I figured HDMI>DVI>VGA would be better than the RCA. I've not had any luck finding any HDMI>VGA adapters that actually work(eg. converting the digital signal to analog).

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Re: RCA Video Quality

Wed Mar 04, 2015 3:20 pm

dbwithlemon wrote:For my purposes I won't need audio.
It's for a specific function, mostly data entry in a browser. But it needs to be clear enough to read from across the room on the TV.
The problem is my TV only has 2 HDMI ports and they're both claimed. My TV doesn't have DVI either, but I figured HDMI>DVI>VGA would be better than the RCA. I've not had any luck finding any HDMI>VGA adapters that actually work(eg. converting the digital signal to analog).
HDMi to VGA Convertors which are Powered are more reliable like:

http://www.ebay.co.uk/itm/HDMI-to-VGA-3 ... 1172649894
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Re: RCA Video Quality

Wed Mar 04, 2015 8:24 pm

I use the RCA and you can read ok on it just most apps like the browser or pistore don't fit in the screen area without editing some files
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Re: RCA Video Quality

Wed Mar 04, 2015 10:30 pm

dbwithlemon wrote:The problem is my TV only has 2 HDMI ports and they're both claimed.
I don't know about your exact situation, but the ports on my TV are fairly easy to reach and I find myself switching around quite a lot. There's almost always useful port shortage on these kind of devices (and abundance of useless ones). I learned to live with it.

Looking forward to the "Project ARA TV edition", where you can slide in 10 HDMI port modules. Then buy the ethernet, VGA, USB and 'smart-whatever' modules only if you really need them.

Until then, I don't let these pesky devices 'claim' my ports. They are MINE! *shakes fist*
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Re: RCA Video Quality

Wed Mar 11, 2015 8:08 pm

panik wrote:
dbwithlemon wrote:The problem is my TV only has 2 HDMI ports and they're both claimed.
I don't know about your exact situation, but the ports on my TV are fairly easy to reach and I find myself switching around quite a lot. There's almost always useful port shortage on these kind of devices (and abundance of useless ones). I learned to live with it.

Looking forward to the "Project ARA TV edition", where you can slide in 10 HDMI port modules. Then buy the ethernet, VGA, USB and 'smart-whatever' modules only if you really need them.

Until then, I don't let these pesky devices 'claim' my ports. They are MINE! *shakes fist*
I completely agree, and I have no issue switching out cables as needed. The problem is I'm setting this up for someone else, and they don't want to mess with that.

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Re: RCA Video Quality

Wed Mar 11, 2015 9:42 pm

dbwithlemon wrote:I completely agree, and I have no issue switching out cables as needed. The problem is I'm setting this up for someone else, and they don't want to mess with that.
Understood. I can do without the hassle as well. Google found some HDMI port switchers that switch x inputs to 1 output. Now I have an itch to buy one myself as a present for me.
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Re: RCA Video Quality

Thu Mar 12, 2015 2:34 am

So long as your TV does a good job of smoothing the interlaced signal you should do well with a good image at up to 720x480. I often run one of my RPi's at that resolution using a composite input on a TV and it looks great.

Again it does depend on the TV, some will not do as well as others.
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