PAL-M is broken

[franmagneto]

When I boot with sdtv_mode=3 or use tvservice -c "PAL_M 4:3" I get 720x576 at 50Hz, but it should be 720x480 at 60Hz like NTSC, that's the correct format for PAL-M.

[popcornmix]

You are right that the behaviour doesn't match the description of PAL-M.
The code seems to change resolution/refresh and colour carrier settings bases on the sdtv mode chosen.
I don't have any PAL-M equipment to test, but I've made changes to the firmware to match what I understand is correct. I may have misunderstood things.

Can you try this test firmware:
https://drive.google.com/uc?id=0B-6zmEDJwxZEd0RhcFR6NHlyXzQ&export=download

and let me know if the behaviour seems better?

[franmagneto]

Thanks for your reply. With this firmware the resolution and frequency is correct, but it still have no colors. If I plug it on a TV expecting NTSC, it shows wrong colors, I think this is not expected, because reading about PAL-M on Internet, it's said that NTSC signal on PAL-M TV shows correct picture, but without colors, and the same happens with PAL-M signal on NTSC TV.

[popcornmix]

So you are testing with a TV that only supports PAL-M?

What was the behaviour with the original firmware?
What is the behaviour with the test firmware?

[pelwell]

Although I haven't found a definitive statement, I suspect that PAL-M uses a 3.58 MHz colour subcarrier (like NTSC) but with PAL encoding, rather than the 4.43 MHz subcarrier of PAL-60.

[popcornmix]

Yes, according to firmware code:

PAL             /* PAL-B,G offset :  4.43361875 MHz. Clock is 13538462. */
PAL_M           /* Colour subcarrier - 3.575611 MHz. Clock is 13369909. */
NTSC/NTSC-J     /* Colour subcarrier - 3.579545 MHz. Clock is 13369909. */

[franmagneto]

You're right, the colour subcarrier frequency is not the same as PAL-60. I have a PAL-M only TV, that outputs monochrome with NTSC signal. When I choose PAL-M on the original firmware the behaviour is the same if I chose PAL, it shows no color and I see horizontal stripes moving. With the new firmware it shows the same as NTSC, clean picture but with no colors. I can use a friend's TV that works with NTSC signal, and on that TV I can see colour with the new firmware, but it's wrong, the four raspberries logo on boot shows like a "rainbow", with color changing along the logos.

[franmagneto]

It still doesn't work with PAL-M, when this mode is selected, the output is NTSC with a "rainbow" pattern

[franmagneto]

I'm still getting no color if the TV is PAL-M. If the TV is set to NTSC, it shows a rainbow pattern, but it must show no color. Maybe the color subcarrier frequency is wrong, I think it must not be the same of NTSC. Wikipedia says that a PAL-M signal shows no color on NTSC TV and vice versa.

I'm also facing the same problem. The equipment I'm using is a National (Panasonic) Panacolor TC-14R1M in pretty good shape, quite popular back in 70's.

I was using a really old Retropie build (outdated for +6mo), so I decided to update the distro+firmware. No luck.

I also tried patches you've released here: #811.
I also tried a clear install + rpi-update (master), but it didn't work.

Then I tried back again to use #811 patches in top of up-to-date fresh install, but it still didn't work.

I started changing sdtv_mode values in /boot/config.txt through PuTTY, save and reboot, and this is what I've found:

Tested with master build 18/07

0 - OK BW
3 - Rolling Screen (BW)
10 - Rolling Screen (BW)
11 - OK (BW)
12 - OUT OF SYNC
13 - OUT OF SYNC
14 - OUT OF SYNC
15 - OUT OF SYNC
16 - OK (BW)
17 - OK (BW)
18 - Rolling Screen
19 - OK (BW)
20 - OUT OF SYNC
21 - OUT OF SYNC
22 - OUT OF SYNC
23 - OUT OF SYNC
24 - OK (BW)

0x20 - I do not recall the result, but no color.
0x22 - I do not recall the result, but no color.
0x30 - OK (BW).
0x32 - Rolling Screen (BW).

Build 23,25 and 27-May patches: #811

0x22 - OK
0x30 - FLICKER (BW)
0x32 - CRAZY FLICKER (BW)

*Out of Sync - Static, no image at all.

I gave up testing because results of #811 although the sync issue, at least they were showing colors. I also tried the sdtv_progressive_scan, but results shown async.

I'd like to help as much as I can. If you provide me firmwares I can trial and error and report results, take pictures, anything.

Thanks in advance.

Best Regards,

[Sobakin76]

I own RPi 3b, and one of my CRT composite monitors is 15" Hitron CVM1574FP which supports many signal standards, including PAL-M.
In Raspbian after sending next commands:
tvservice -c "PAL_M 4:3 P"
fbset -xres 640 -yres 240 -match -a
fbset -depth 8;fbset -depth 32
when monitor in Auto mode it autodetects as NTSC or when I choose NTSC manually it shows this pitcure (running Midnight Commander):

Absolutely the same picture is in another monitor, JVC TM-H150CG, which autodetects sync and color system independently, so it correctly supports PAL-60 but I don't know about PAL-M (don't have such properly working signal source to check):

You may see what a little part of picture (column right after center) is shown in correct colors, but monitors in NTSC mode, not PAL-M.

When I switch monitor (Hitron) manually to PAL M, it shows B&W picture:

And when I switch RPi output to NTSC by
tvservice -c "NTSC 4:3 P"
It autodetects NTSC and shows correct image, except NTSC color artifacts, which almost no see on this photo:

but I don't like NTSC because of color artifacts in games (Grand Prix Cirquit in 4-color CGA mode in DOSbox), on both monitors the same (first is Hitron, second is JVC):

In pure PAL colors is ok, but image flickers (50Hz only) and is too compressed in vertical because higher scan lines count (288 lines in PAL vs 240 in NTSC/PAL-M/PAL60 progressive)

Okay, I've tried

tvservice -c "flag 4:3 (P)" with NTSC, PAL and PAL_M, also enabling/disabling P progressive scan. Just after doing setting tvservice, images goes black, reboot and all of them image pops up. No rolling screen or static. Clear, but no colors. :/