rcdrone wrote:I've been doing a bunch of experiments with the the 240p test suite on my Wii to try to calibrate my capture card (SC-512N1-L/DVI) and CRT (BVM-D20F1U) with the SMPTE color bars. I have a couple questions, and various observations.
Thanks for the feedback, my replies below.
rcdrone wrote:
- If the Wii is mapping 0-255 to 0-100 IRE, doesn't that mean it's sending NTSC_M_J limited? Since 0/7.5 (J/!J) IRE = 16, and 100 IRE = 235 from what I can Google, it seems like the Wii itself is compressing the color range from 0-255 -> 16-235 before sending it over the wire.
It never does any compression, checked with the scope. In reality it always does 0-255 (NTSC-J read below)
rcdrone wrote:
- If I use composite, my capture card driver says the color space & range are unknown, but if I use component, the driver says it's BT601/LIMITED. Maybe there's some metadata encoded in the signal; I'm not sure how the driver would know otherwise.
It probably does the guesswork via voltages. There is no need for metadata when the signal itself is distinct via it's sync values and color levels. Try using full range though.
rcdrone wrote:
- I tried Smash Melee in Dolphin and it uses colors darker than 7.5 IRE (<19/19/19), which suggests I should be calibrating for 0 IRE rather than 7.5 IRE, at least for Wii. My SNES is also definitely guilty of going darker than 7.5, but what about NES? I can't seem to find conclusive evidence.
Yes, always use full range for (Japanese designed/older) game consoles.
rcdrone wrote:
- Using STD D65 on my BVM, auto-calibration seems to work well over component: 7.5 shows only the 29 pluge bar, and 0 shows 9/19/29 pluge bars. Composite auto-calibration doesn't seem to behave correctly though. I can see all three pluge bars in 7.5 and 0, and the chroma is so high that it causes colors to bleed on my NES games. (The chroma issue may also affect component; I haven't checked.) In fact, 7.5 and 0 settings don't look different at all over composite. I think the test suite image is fine though; this is just how things are shaking out with my display.
Yes, it is best to calibrate by eye. Game console video signals are compatible with broadcast standards, but they don't follow them strictly. They are just "good enough", although the newer the console, the better they adhere to the standards. I mean that older ones are worse at that.
rcdrone wrote:
- I wrote a little tool to test the RGB values of my capture card feed, so I can adjust brightness/contrast/saturation in the driver to try to match the PNG values (NTSC_M_J), or rescaled values 19.125-255 -> 0-255 (NTSC_M). It seems like NTSC_M and NTSC_M_J in my driver do more than just adjust the 0/7.5 black level, so I have different calibration values for each.
Technically, NTSC-J uses 9300K instead of 6500K. That might be your issue. Game consoles usually have the same output signal for all NTSC regions.
rcdrone wrote:
- I'm not sure why, but switching between NTSC_M and NTSC_M_J in the capture card driver has noticeable results over composite, but doesn't seem to do anything over component.
Component does not conform to NTSC.. I mean, strictly speaking NTSC only applies to composite and over the air transmision. But we all use the term loosely to refer to 60 fps. You should use NTSC-J with consoles since it is full range though.
