relaxpi4
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Real 16:9 SD video out?

Sun Nov 10, 2019 12:22 pm

Hi

i like to use My Pi2 model B for a local TV station, where we need 16:9 SD analog 720x576i output signal.

I already set this in config.txt
sdtv_mode=2 (for PAL)
sdtv_aspect=3 (for 16:9)

But on the composite output i still have 4:3 ratio, with black bars at left and right.
Why? What else is needed to output correct widescreen signal?
43.jpg
43.jpg (85.37 KiB) Viewed 468 times
Many thanks!

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topguy
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Re: Real 16:9 SD video out?

Mon Nov 11, 2019 2:37 am

I'm not quite sure what you are trying to achieve to be honest..

720x576i resolution is classic PAL 4:3 aspect ratio. There are no 16:9 analog signals, (AFAIK) there was never any part of component/composite signals that could tell the TV that it should show it in 16:9.
Its the 16:9 TV that chooses to either show the picture as 4:3 or stretch it to fullscreen (16:9), usually you press the "zoom" button on the remote to choose that.

relaxpi4
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Re: Real 16:9 SD video out?

Mon Nov 11, 2019 4:49 am

No, there is 16:9 anamorph signal, so TV's can know if it should stretched horizontally or not:

https://en.wikipedia.org/wiki/Widescreen_signaling
http://www.vsicam.com/_faq/what-is-wss- ... ct-ratios/

So why my PI doesn't output this extra signal? And if cannot what sd_aspect parameter really does?
Of course I can set my TV manually to 16:9 but i like to use this Pi for local TV station video playback, so all viewers should set aspect ratio manually, which is not a solution.

thanks!

fruitoftheloom
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Re: Real 16:9 SD video out?

Mon Nov 11, 2019 5:40 am

relaxpi4 wrote:
Sun Nov 10, 2019 12:22 pm
Hi

i like to use My Pi2 model B for a local TV station, where we need 16:9 SD analog 720x576i output signal.

I already set this in config.txt
sdtv_mode=2 (for PAL)
sdtv_aspect=3 (for 16:9)

But on the composite output i still have 4:3 ratio, with black bars at left and right.
Why? What else is needed to output correct widescreen signal?

43.jpg

Many thanks!

raspi-config change the overscan setting ??
Retired disgracefully.....

relaxpi4
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Joined: Tue Sep 10, 2019 1:15 pm

Re: Real 16:9 SD video out?

Mon Nov 11, 2019 6:12 am

No, it's not an overscan issue.
It's a wrong aspect ratio problem.

fruitoftheloom
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Re: Real 16:9 SD video out?

Mon Nov 11, 2019 7:42 am

relaxpi4 wrote:
Mon Nov 11, 2019 6:12 am
No, it's not an overscan issue.
It's a wrong aspect ratio problem.

How are you connecting the RPi Composite Output to the TV ? Convertors / Adaptors ?


This cable worked for me on a modern Wide-screen HDTV when had an older RPi:

https://thepihut.com/products/av-compos ... 3-x-rca-3m
Retired disgracefully.....

relaxpi4
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Re: Real 16:9 SD video out?

Mon Nov 11, 2019 7:47 am

Yes, with a 4 pin cable, no converter.
The picture is good, only the aspect ratio isn't, because Pi doesn't output the embedded WSS signal.
WHY?

fruitoftheloom
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Re: Real 16:9 SD video out?

Mon Nov 11, 2019 8:37 am

relaxpi4 wrote:
Mon Nov 11, 2019 7:47 am
Yes, with a 4 pin cable, no converter.
The picture is good, only the aspect ratio isn't, because Pi doesn't output the embedded WSS signal.
WHY?

Maybe your TV can not "auto switch" to 16:9 with composite signal ??

Try another TV ??
Retired disgracefully.....

relaxpi4
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Re: Real 16:9 SD video out?

Mon Nov 11, 2019 9:09 am

No, my tv can switch to 16:9, when the WSS signal is detected.
From my Sony camcorder's analog out, it auto switch to 16:9 PAL.

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Re: Real 16:9 SD video out?

Mon Nov 11, 2019 10:15 am

relaxpi4 wrote:
Mon Nov 11, 2019 7:47 am
Yes, with a 4 pin cable, no converter.
The picture is good, only the aspect ratio isn't, because Pi doesn't output the embedded WSS signal.
WHY?
Don;t know. Will ask around, but it may be the composite out simply cannot generate the correct timings.
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relaxpi4
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Re: Real 16:9 SD video out?

Mon Nov 11, 2019 10:19 am

Thanks
then i need a wss signal inserter, which isn't cheap :(

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Re: Real 16:9 SD video out?

Mon Nov 11, 2019 10:46 am

Looking at the code, it's definitely setting up a 16:9 anamorphic mode, via WSE/WSS. So maybe Kodi is getting its pixel aspect ratio wrong (this mode uses wider pixels), will ask the Kodi expert when he gets in.
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relaxpi4
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Re: Real 16:9 SD video out?

Mon Nov 11, 2019 10:50 am

At booting (before starting Kodi) i also only have 4:3 picture on my TV.
I tried with raspbian too, still don't see any effect of sdtv_aspect=3 parameter.
What about Pi3 and 4?

jamesh
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Re: Real 16:9 SD video out?

Mon Nov 11, 2019 11:41 am

relaxpi4 wrote:
Mon Nov 11, 2019 10:50 am
At booting (before starting Kodi) i also only have 4:3 picture on my TV.
I tried with raspbian too, still don't see any effect of sdtv_aspect=3 parameter.
What about Pi3 and 4?
I don't have a composite setup handy to test, so I do not know. All I can say is that the code for setting up 16:9 does appear to be in there. To double check it's being set up what does `vcgencmd get_config int` return for the sdtv_aspect setup.
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relaxpi4
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Re: Real 16:9 SD video out?

Mon Nov 11, 2019 11:48 am

Yeah, that's fine, but tv doesn't stretch.
aspect.jpg
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jamesh
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Re: Real 16:9 SD video out?

Mon Nov 11, 2019 11:54 am

In the image in the first post, the date at top right appears to be in right place - is that added by Kodi or the TV? If Kodi, then the TV would be displaying 16:9 correctly, and its Kodi's GUI that is not correct.
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relaxpi4
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Re: Real 16:9 SD video out?

Mon Nov 11, 2019 11:58 am

That's sadly my TV.

relaxpi4
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Re: Real 16:9 SD video out?

Mon Nov 11, 2019 6:42 pm

update: even my old, cheap philips dvd recorder can output 16:9 signal with 16:9 disc..
Why Pi, why not?

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Re: Real 16:9 SD video out?

Tue Nov 12, 2019 8:02 am

It can, so I don't know why it isn't working.
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6by9
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Re: Real 16:9 SD video out?

Tue Nov 12, 2019 12:08 pm

There is no such thing as 16:9 SD video in the video element of composite video. As you've stated, the resolution is 720x576 which is 5:4.
You're referring to the widescreen signalling (WSS), which is a side-channel.

The Pi is a computer, not a DVD recorder. When your computer produces WSS correctly then feel free to complain.
I suspect you'll have further entertainment getting whatever application you're using to understand that you no longer have square pixels either.

And I suspect that your DVD recorder is using the widescreen selection via pin 8 of the SCART connector rather than WSS embedded in the video stream.

James: I do have an analogue video capture board that can read the WSS signalling state if you want to follow this up. The DVD player on my desk should be able to produce the relevant signals as a reference source.
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relaxpi4
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Re: Real 16:9 SD video out?

Tue Nov 12, 2019 12:15 pm

Of course i know that 16:9 SD video is made by 720x576 pixels, stretched across the screen horizontally,
just like 4:3 video, which also doesn't use square pixels..

You are wrong, my dvd recorder output the wss signal via rca composite output!

"When your computer produces WSS correctly then feel free to complain."
Ok, but then what is the reason for sdtv_aspect parameter in config.txt?
What does it exactly?

many thanks!

6by9
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Re: Real 16:9 SD video out?

Tue Nov 12, 2019 12:51 pm

relaxpi4 wrote:
Tue Nov 12, 2019 12:15 pm
You are wrong, my dvd recorder output the wss signal via rca composite output!
Someone obviously checked through all the options of their hardware then. Many manufacturers don't.
relaxpi4 wrote:"When your computer produces WSS correctly then feel free to complain."
Note I'm referring to an x86 or any other mainline Linux computer here.
relaxpi4 wrote:Ok, but then what is the reason for sdtv_aspect parameter in config.txt?
What does it exactly?
It is setting the register in the VEC (Video EnCoder) hardware block to set up WSS.

I think the issue may be a simple one that the register setting what the WSS value should be is programmed, but not the overall control register. There is an option to call it via a remote service, but that won't happen by default. The main issue being that it's a tough one to test without a suitable display device. It'll get added to the list of things to test, but it's a long list.
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relaxpi4
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Re: Real 16:9 SD video out?

Tue Nov 12, 2019 12:59 pm

ok, thanks
wdtv mini is a mediaplayer, which has "display output mode 16:9" in the menu, but still doesnt embed WSS signal :(
I have to find a cheap dvd player with wss and autoplay feature and go back 6 years, when we used to create dvd's :o .

6by9
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Re: Real 16:9 SD video out?

Tue Nov 12, 2019 1:06 pm

A quick check with the debugger does appear to say that the WSS core just isn't being enabled. It's a copy/paste of one register configuration from one function to another. The annoyance being that it appears to be invalid for NTSC, so therefore it actually needs to be conditional.

The fact that no one has complained since the launch of the first Pi in 2012 until now gives an indication as to how important that feature really is.
Nevertheless I'll see if we can sort a fix.
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relaxpi4
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Re: Real 16:9 SD video out?

Tue Nov 12, 2019 1:32 pm

Yes, for single users it's fine, because we can set our Tv's aspect ratio manually with the remote.
But i like to use my Pi2 as a mediaplayer for a small TV station (few hundred viewers..)
Anyway, i will donate you if it will work fine :)

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