S-VIDEO output on B4 with orginal kernel and u-boot

Hi all,

I've just received a beagle rev B4. As of now, I'm using software
which comes from beagleboard.org.

Almost everything looks fine. I followed instructions located in the
project website and I can boot the board.
Even with a file system built by my own. And that is just great!. I
had no problem to setup it.

I'm just wondering about the S-VIDEO output.

The u-boot which comes with this board does some testing. It seams to
put the display controller in test mode
for S-VIDEO. I can see output with colored lines on TV. However, the
TV standard seams to be misconfigured.
I've test it in two different TVs. One of those the output is black
and white only. The other one the output is somehow
colored, but with a bunch of noise.

I tested its S-VIDEO output with Linux kernel configuration as well.
Using the kernel which comes from this link:
http://www.beagleboard.org/uploads/2.6_kernel-beagle-rev2.tar.gz

I got S-VIDEO output working as well after some hacking in the device
driver. I've just changed the size of video
output as recommend in l-o by :
http://marc.info/?l=linux-omap&m=121240865530550&w=2

However, with the same behaviour. No correct TV standard.
By default, it configures video encoder device to NTSC-M. But changing
it on tv_standard sysfs property
does not help.

So, here is one question, do you guys have this same behaviour for the
S-VIDEO output? I was wondering if
I got a board with hardware problems into its S-VIDEO :).

Cheers,

As pointed out to me, there are knobs you can twiddle for the
S-Video out:

http://code.google.com/p/beagleboard/wiki/LinuxHints

Can you tell me what resolution you are setting the TV to and
what standard are you using?

I have the driver you pointed running in an older version of the
OMAP git tree and am trying to tweak it before posting the patches
for it. Unfortunately, it isn't working quite right. Seems like
the output is rotated and shrunken in the upper left area. I do get
a stable display; this is on NTSC.

-- Hunyue

No, all boards may be behaving the same on S-Video. I had faced the same issue of noise, but then I replaced my S-video Cable to a different one, it was bit better. There could also be some more settings to be tuned, which we are working on.

Regards,
Khasim

Hi Hunyue,

As pointed out to me, there are knobs you can twiddle for the
S-Video out:

http://code.google.com/p/beagleboard/wiki/LinuxHints

Yes, I'm using those as well.

Can you tell me what resolution you are setting the TV to and
what standard are you using?

I'm using 640x480 NTSC-M. I didn't touch the tv standard code. It is
NTSC_M by default.
I've just changed H4_LCD_[X,Y]RES definitions to 640x480.

I have the driver you pointed running in an older version of the
OMAP git tree and am trying to tweak it before posting the patches
for it. Unfortunately, it isn't working quite right. Seems like
the output is rotated and shrunken in the upper left area. I do get
a stable display; this is on NTSC.

Seams interesting. I'm having the same issue about the upper and left area.
But it is not rotated.

There is an issue with the OMAP3 silicon that can result in a noisy S-Video output. The degree to which the noise is evident is also related to the quality of the S-Video receiver. Some S-Video devices will look better than others.

Gerald

Hi Khasim,

<snip>

No, all boards may be behaving the same on S-Video. I had faced the same
issue of noise, but then I replaced my S-video Cable to a different one, it
was bit better. There could also be some more settings to be tuned, which we
are working on.

Actually, I'm using a S-video to RCA cable.

I'm using a cable with a 470pF capacitor between Chroma and Luma signals.
You can see the schematic for this cable here:
http://www.boadica.com.br/imaginesdica/svideorca.gif

What cable are you using?

There is an issue with the OMAP3 silicon that can result in a noisy S-Video output. The degree to which the noise is evident is also related to the quality of the S-Video receiver. Some S-Video devices will look better than others.

Gerald

Gerald,

In my case, I don't think noise is the issue. That same cable/display
works with U-boot to display the color bars and I definitely see
noise on the right color bars but the bars are definitely discernable.
This is with a commerical passive S-Video to composite adapter.
The display is a LCD originally intended for video game systems.

-- Hunyue

Hi Hunyue,

>
> As pointed out to me, there are knobs you can twiddle for the
> S-Video out:
>
> http://code.google.com/p/beagleboard/wiki/LinuxHints

Yes, I'm using those as well.

>
> Can you tell me what resolution you are setting the TV to and
> what standard are you using?

I'm using 640x480 NTSC-M. I didn't touch the tv standard code. It is
NTSC_M by default.
I've just changed H4_LCD_[X,Y]RES definitions to 640x480.

>
> I have the driver you pointed running in an older version of the
> OMAP git tree and am trying to tweak it before posting the patches
> for it. Unfortunately, it isn't working quite right. Seems like
> the output is rotated and shrunken in the upper left area. I do get
> a stable display; this is on NTSC.

Seams interesting. I'm having the same issue about the upper and left area.
But it is not rotated.

How do you determine it is not rotated? What I did is enabled fbcon and
not the direction of scrolling when I send output to /dev/tty1, i.e.
ls -lR /sys > /dev/tty1.

What software are you using to check this? Also, do you have some version of
the *_LCD_VGA enabled (i.e. grep _LCD_VGA .config)? The actual name varies
depending on where the kernel came from. I don't expect it to make a difference
but it does seem to have an effect in my case.

-- Hunyue

I see. OK. I don't know that we have tried the composite configuration on the board. I know there is a way to do it, but to my knowledge you are the first to do it. There could indeed be some tweaks in the settings required to make composite video happen.

If you look in there is a mode to do composite, but only one lead is used the capacitor you have in your diagram is not there. Only one lead is used. I suggest you look at the OMAP3530 TRM under the composite video. There may also be a need for some register settings, but I ma not positive on that.

Gerald

I see. OK. I don't know that we have tried the composite configuration on the board. I know there is
a way to do it, but to my knowledge you are the first to do it

Just a thought: Using Omap to do composite on beagle:
:slight_smile: I recollect we had hacked 3430 on SDP to bring out composite. All u need to do is this:
VENC_OUTPUT_CONTROL reg gets composite enable(bit 1) set instead of 0 and 3. the hack would work cos the same lines are shared for s-video and composite :D.. So you could get a rca socket and a s-video jack and solder them to create a "omap composite adapter" without any capacitors :D.

Also a small note: the very few cases I have heard of noisy image in tv on sdp3430, we had tracked it to a bad quality s-video cable guys had used.. dunno why we saw noise though....

Regards,
Nishanth Menon

Hi Hunyue,

Sorry, but I think I misunderstood something
<snip>

Seams interesting. I'm having the same issue about the upper and left area.
But it is not rotated.

What I mean here was the screen was not rotated as you can rotate it
with xrandr.

How do you determine it is not rotated? What I did is enabled fbcon and
not the direction of scrolling when I send output to /dev/tty1, i.e.
ls -lR /sys > /dev/tty1.

The screen seams to be in the correct orientation when outputted on TV.

What software are you using to check this? Also, do you have some version of
the *_LCD_VGA enabled (i.e. grep _LCD_VGA .config)? The actual name varies
depending on where the kernel came from. I don't expect it to make a difference
but it does seem to have an effect in my case.

No, they are not enabled.

-- Hunyue

<snip>

Hi,

I see. OK. I don't know that we have tried the composite configuration on the board. I know there is
a way to do it, but to my knowledge you are the first to do it

Just a thought: Using Omap to do composite on beagle:
:slight_smile: I recollect we had hacked 3430 on SDP to bring out composite. All u need to do is this:
VENC_OUTPUT_CONTROL reg gets composite enable(bit 1) set instead of 0 and 3. the hack would work cos the same lines are shared for s-video and composite :D.. So you could get a rca socket and a s-video jack and solder them to create a "omap composite adapter" without any capacitors :D.

Also a small note: the very few cases I have heard of noisy image in tv on sdp3430, we had tracked it to a bad quality s-video cable guys had used.. dunno why we saw noise though....

I thought this hack would work as well. But I tried and it not
resulting as expected.
I hacked a 3430 based SDP. When I enable the composite bit on
VENC_OUTPUT_CONTROL and disable
the luma and chroma bits, no signal is outputted. This is something
that I really didn't understand. Because
as you said Luma and Composite share the same output. Is there
something else needed to have composite
output working?