Reply To: TV compatibility report thread

[AetherSmith]

Vizio M70-C3

Okay, I completely removed the old report because it was based on a firmware several versions old; this report is based on v0.77 on a v1.5 DIY kit.

Update: Upgraded to v0.78; no changes in compatibility. Added result for Sega Master System.
Update: Added notes on the quirks of HDMI5 regarding pixel aspect ratio, results for GameCube and PSP.

Like many of the current crop of 4K TVs, the M70-C3 will perform differently depending on which HDMI port is used. For my testing, I used HDMI5 (the sole 4K@60-enabled port) and HDMI4 (one of the others). I did my actual testing with the OSSC plugged directly into the port being tested, but later confirmed that switching the signal through my AVR (a Denon AVR-S910W) with all the HDMI processing features turned off did not affect stability or lag.

I did testing using the 240p test suite for both Wii and Dreamcast (the only two consoles I can run it on at the moment), with RGB SCART sources switched through a gscartsw_lite, component through an Impact Acoustics 6/2 switch, and Dreamcast VGA plugged directly into the OSSC. For lag testing, I tested against a Sony PVM-14M4U I managed to get ahold of recently. I made sure to set the monitor up so that, in the frame of the test photos, it roughly matched the height and vertical positioning of the TV in order to avoid the risk of rolling-shutter error.

HDMI5

Lag: ~1 Frame
240p/480i Resync: ~3.3 Seconds

240p Passthrough: No
240p x2: Yes
240p x3: Yes
240p x4: No
240p x5: No

480i Passthrough: No
480i x2: Yes
480i x3: No
480i x4: No

480p Passthrough: Yes
480p x2: No

1080i Passthrough: Yes
1080i x2: Yes

Notes: This input is less compatible, but has far less picture processing and lag. In fact, this input seems to be unable to do any actual interpolation, simply doing the maximum possible integer scale of whatever it receives: 720p and 1080i/p use the full screen, while 480p signals seem to be multiplied to 4x and then windowboxed. The lack of interpolation capability does lead to an unexpected quirk (which I missed at first), which is that all content is displayed with square pixels regardless of its intended pixel aspect ratio. This is all well and good for any HD or 480p VGA content, but it means that any 480p DTV content ends up displayed at an aspect ratio of 3:2 rather than 4:3 or 16:9.

HDMI4

Lag: ~3-5 Frames
240p/480i Resync: ~2.5 Seconds

240p Passthrough: No
240p x2: Yes
240p x3: Yes
240p x4: Yes
240p x5: Yes (All Modes)

480i Passthrough: Yes
480i x2: Yes
480i x3: No
480i x4: No

480p Passthrough: Yes
480p x2: No

1080i Passthrough: Yes
1080i x2: Yes

Notes: This input is much more compatible, but also has much more lag and intrusive picture processing. There are a few possible scaling options for a given resolution, supporting both 4:3 and 16:9 games when using a 480i/p console. Since this input has full interpolation capabilities, it doesn’t share the issue regarding pixel aspect ratio.

Consoles Tested

NES (NESRGB – RGB SCART)
Master System (RGB SCART)
Genesis (RGB SCART)
Super Nintendo (RGB SCART)
PlayStation (RGB SCART)
Saturn (RGB SCART)
Nintendo 64 (THS7314 Amp – RGB SCART)
Dreamcast (Kuro – VGA)
PlayStation 2 (Component)
GameCube (D-Terminal w/ component adapter)
Xbox (Component)
PlayStation Portable (Component)
Wii (Component)

Other Thoughts

In general, both inputs were quite stable with signals from the latest firmware version

While the processing is lighter on HDMI5, it’s not entirely absent. It’s most noticeable in causing the scanlines to seemingly group into pairs of two that have a thin, hard-edged dark line between them and thicker, softer-edged lines on either side. I don’t find it visible from my viewing distance (about 10 feet from the 70″ TV), but if I were a bit closer it would definitely prove annoying.

Interestingly, when forced to resync, the picture doesn’t return on HDMI5 until around a second after the resolution information is displayed onscreen. When using HDMI4, by contrast, the picture returns at the same time its resolution info appears. This discrepancy appears to account for the shorter resync time when using HDMI4.

Overall, I’m reasonably pleased with the TV’s compatibility with the OSSC. I’m perfectly happy with linetriple for classic games, while I can bear with the lag to properly scale the 480i/p of later games. While I’d definitely be interested if a good 4K video scaler comes on the market to add to the chain here, as it stands now I’m happy enough with the setup as it is. Since my AVR has dual outputs, I was able to pretty easily set things up so that I can switch between HDMI4 and HDMI5 for the best of both worlds.