ST1080 – how bad does it get?

I’ve been asked to record some video of how the ST1080 really performs. In most cases, it’s not a bad experience, but knowing its limitations I decided to set about reproducing the actual problems. I also gave a try at video editing to see if I could present this in a helpful manner, but in the end that turned into just a bad excuse for further procrastination so I’ve decided to publish raw files showing the performance of the ST1080. The files in there are a jumble and very easily misinterpreted, so here’s a bit of a guide. Beware: A lot of the video clips are high speed footage, so expect extreme amounts of flickering. This can be dangerous to some individuals, such as optically triggered epileptics.

CIMG 2880 through 2892 show the stain in the left lens that troubled me earlier. It is now gone, and might have been as simple as some condensation on the rear lens.

CIMG 2893 shows a peek through the front of the ST1080; it’s very reflective at the partially translucent mirror, and the covering it’s shipped with is not very good for reapplying after stripping off (it stretches). The extras included appear to be a different type, however.

CIMG 2894 through 2897 are high speed video clips of static images, showing the sequential color field display technique used by the ST1080. Setting a lower brightness simply reduces the length of each strobe, likely making the so-called rainbow effect worse, not better.

CIMG 2898 through 2904 are high speed footage of a moving test pattern (a simple vertical colored bar, moving side to side and changing colors, synchronised to vblank). They did not really show anything particular, though one effect of the sequential fields is that objects suddenly switching color may stagger since they’re not shown in an even frame rate.

CIMG 2905 is a 1000fps video showing the HMZ-T1 (on the left) and ST1080 (on the right). Both are fed the same video signal through an HDMI splitter, and that signal is live from a video camera into which we blink an LED light. It thus shows very sharp transitions between a fully lit and dark picture. Here I expected the HMZ-T1 to show pictures before the ST1080, because unlike the ST1080 it not only shows all colors at once but scans similarly to a traditional CRT (notable by a dark band sweeping across the display). What I found surprised me – you can count about 80ms delay in the HMZ-T1, remarkable as we know the ST1080 is already delayed about 17ms.

CIMG 2906 and 2907 are pictures I’ve posted before, approximating the difference in field of view for those two devices. The color error in the ST1080 is simply because the exposure is not well aligned with the color sequence.

CIMG 2908 is a high speed recording of live motion (a swinging foot) displayed by the ST1080. While it’s not clearly visible, the ST1080 accepts interlaced material and displays full frames with half the lines updated – a method that can cause a comb effect. I believe the camera in this instance is sending progressive frames as an interlaced signal. Nothing to really remark on.

CIMG 2920 and 2921 is some high resolution video showing fumbling around and a bit of Big Buck Bunny. Nothing to see here. Colors go nuts as usual. The bright spots aren’t live pixels but dust in the display module, an issue I understand SMD have done work to avoid in later units.

CIMG 2922 through 2926 show the beginning of Elephants Dream. This is of note because it has just the sort of scene the ST1080 does badly at; high motion, dark, yet high contrast. The dark scene makes the side light bleeding much more noticable, and the moving high contrast detail triggers the “rainbow effect” quite handily. The frame rate of the source material and display differ, however, so don’t blame uneven motion on the ST1080.

CIMG 2927 and 2928 show a cheap camera shutter bouncing. Nothing to do with the ST1080, but at this point I’ll just leave it there and see if anyone remarks on it.

CIMG 2929 through 2932 are stills of the display; 2930 in particular manages to show that the color reproduction isn’t all bad.

CIMG 2933 through 2935, 2941 and 2942 again show Elephants Dream (the file being played is also in the folder as ED_HD.avi). In particular 2935 has about 9 minutes of it, thus showing a lot of different scenes.

CIMG 2936 through 2940 are test stills attempting to show the display resolution. This is xclock with antialiasing turned off, so we should get some pixelated diagonal lines to examine. The lower resolution shots are the rescaled 720p mode, in which I have not yet noticed any problems. That is more than I can say of any of the 3D capable games I tested it with, because they all render at even lower resolutions and have horrible scaling artefacts on top of sad frame rates.

CIMG 2943 shows something remarkable. It’s a fairly static display, but is supposed to be 24fps output from an nvidia board. Now, I don’t have another 24fps display to compare with, but to my eyes this looked horrible, and the 240fps footage shows precisely what’s going on. We seem to be getting nearly precisely 240 fields per second – which raises the question, with three colors to show, what is the tenth field? – and therein lies the problem. The tenth field is black, but the LED is still strobing through a sequence of colors. For some reason, this lights up the border around the picture brightly, causing a 24fps strobe in different colors. Now, even at the cinema they know 24fps is never enough – that’s why they triple it, just like here. But with the color sequence I’m seeing frames going gBRGBRGBRG rGBRGBRGBR bRGBRGBRGB. So aside from tripled frames with a different field order each frame, we get strobes of light not involved in the picture. The proper fix is to simply not strobe the LEDs for the blank time slot, but this may be impossible to fix in the updatable firmware if it’s in the display module rather than the control box. As is, I must sadly report that 24fps is unusable on the ST1080 (but they could possibly fix it in another firmware update).

Finally, the MOV files are some useless video footage of the way I shot CIMG 2929 through 2942. And yes, the camera this is shot with can do 1080p24, but it cannot photograph the pictures within HMDs well because the lenses are too large.

I basically agree with a statement I saw on the MTBS3D forum: The ST1080 is the best consumer HMD yet, and not yet very good. I believe this market is in its infancy and the two devices mentioned here are just at the threshold; the ST1080 is good enough for me to purchase, but not to use most days as I had envisioned.

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