CurtPalme.com Home Theater Forum

[Phoenixed]

Thanks for the answer Dennis. I figured no matter which way the DVI still limited the marquee.

[Nashou66]

Ok DVI/HDMI will do over 165mhz, it will sync and display as long as the display will sync to it. Now will it fully resolve a 1x1 pixel? Probably not. Over on the TV-One thread at AVS the tv-one engineer used to post there. they ran 1080p@85hz which is over 200mhz pixel clock, they couldnt push it further because the display went wacky. I asked him via email how they sent the signal, He said single link DVI then added they went to dual link after the display went watch thinking it was the cable, even with dual link the display gave up making them believe it was their display and not the DVI connection. Now I was using a short cable maybe 1.5m. Longer for sure might give drop outs etc. They under rate the cables from what that engineer told me and said most DVI/HDMI of good quality can go over 165 easily as long as its shorter than a few meters.

Athanasios

[Phoenixed]

I am pushing 25 foot right now. Will be shorter when the marquee gets hung.

[dvh99]

Single-link DVI
A single-link DVI connection consists of four TMDS links; each link transmits data from the source to the device over 1 twisted wire pair. Three of the links correspond to the RGB components of the video signal: red, green, blue (for a total of 24 bits per pixel.) The fourth link carries the pixel clock. The binary data is encoded using 8b10b encoding. The 8b10b encoding system serves several purposes: it preserves DC balance over time, it generates sufficient signal transitions to maintain receiver bit-alignment (pixel clock recovery), and it provides symbol (byte) alignment. Each TMDS link carries binary data at ten times the pixel clock reference frequency, for a maximum data rate of 1.65 Gbit/s × 3 data pairs for single-link DVI.
DVI does not use packetisation, but rather transmits the pixel data as if it were a rasterized analog video signal. As such, during each vertical refresh period, the complete frame is 'drawn' over the DVI link. The full active area of each frame is always transmitted; no data compression is used, and there is no support for only transmitting changed parts of the image. Video modes typically use horizontal and vertical refresh timings that are compatible with CRT displays, but this is not a requirement. The DVI specification (see below for link) does, however, include a paragraph on "Conversion to Selective Refresh" (under 1.2.2), suggesting this feature for future devices.
The DVI specification mandates a maximum pixel clock frequency of 165 MHz when running in single-link mode. With a single DVI link, the highest supported standard resolution is 2.75 megapixels (including blanking interval) at 60 Hz refresh. For practical purposes, this allows a maximum screen resolution at 60 Hz of 1,915 × 1,436 pixels (standard 4:3 ratio), 1,854 × 1,483 pixels (5:4 ratio), or 2,098 × 1,311 (widescreen 16:10 ratio).

this is from wikipedia.

[dvh99]

i experienced the picture to be folded when going over the 165mhz limit into the moome.
a friend of mine has bought a videocard with hdmi out to avoid this problem.

there could be a way out of this if you know how to hack the dvi encoding system.

[Nashou66]

Yes and that is the standard for minimum bandwidth. only super cheap crapy cables are limited to 165 most will do way way over. Its just a minimum standard, thats all.

Athanasios

[dvh99]

have you read the last 3 sentences from the wikipedia article?

[Nashou66]

[Nashou66]

And anyhow HDMI 1.3 which most cables are can do 340mhz. The cable from the DVI connector to the HDMI connector does nothing to lower that number. DVI/HDMI are the same for all intensive purposes. Like I said Most cables will do more than the speced 165.

HDMI 1.3 Released June 2006.

* Increases single-link bandwidth to 340 MHz (10.2 Gbps)
* Optionally supports 30-bit, 36-bit, and 48-bit xvYCC with Deep Color or over one billion colors, up from 24-bit sRGB or YCbCr in previous versions.
* Incorporates automatic audio syncing (lip sync) capability.
* Supports output of Dolby TrueHD and DTS-HD Master Audio streams for external decoding by AV receivers. TrueHD and DTS-HD are lossless audio codec formats used on HD DVDs and Blu-ray Discs. If the disc player can decode these streams into uncompressed audio, then HDMI 1.3 is not necessary, as all versions of HDMI can transport uncompressed audio.

Athanasios

[jbmeyer13]

[dvh99]

i think the hdq simply wasnt adding porches because you exceeded the 165mhz bw limit and thus had ringing.

try to feed the pj a 1920*800 at 60 hz with the same hor porch settings and you will see the ringing is gone just like it is at 1920*1080*48hz.

[dvh99]

[Nashou66]

well i must be defying known physics then Dennis my friend.


Nashou

[jbmeyer13]

Quick update. Now that I'm back from a business trip and have time to fool around with my Marquee, here's where I'm at:

At 72Hz I noticed ringing (1980 x 800/72hz), and adjusting porch settings had absolutely zero effect on this. Consequently, I followed advice from both Nash and Dennis. I used Dennis H porch settings:

HTOT 2368
ACT 1920
HSYN 104
HFRN 56

and then used Nash's method of increasing the raster to move the ringing out of the way. I increased the raster so that the edges ended up touching the side of the tube face (but didn't wrap around). Then I centered the raster horizontally and vertically using the green random access under the service menu for convergence. Next, I used the Marquee phase in conjunction with HQD position controls to get the active image in the right location and finally I'll be tweaking the S/C Linearity to achieve optimal geometery. At the end of the day, the active image has the same size and location as 1080p/48hz, but the raster is slightly larger thus moving the ringing outside the active image area.

[dvh99]

i don`t get you guys.

reducing or increasing raster size does nothing to eliminate ringing, it`s increasing backporches that counts.

here is a neat trick btw.

enter the porch settings to have no ringing and then go into the convergence on green menu and center the active image on the tubeface and try to make the active image as big as possible.

[Nashou66]

[jbmeyer13]

Dennis- Do you agree that if the horizontal width of the raster increases then the ringing shifts to the left?

I have tried a variety of porch settings; i.e. increasing the back porch and it did nothing to reduce ringing. Iv'e tried between 1.5 and 2.4 us and no dice

[Nashou66]

[dvh99]

[dvh99]

one other thing, blanking must be set to 0 and phase must be set to 50 (vert and horizontal)

and you have to set the projector on short retrace, (pic on remote option 8)