Panasonic PRO-505PU/PRO-1120HD plasma display: input lag / upscaling /deinterlacing review
This 50" plasma TV dates back to 2005, and is an odd beast, with a "flat" panel TV unit with no speakers and just a DVI input on back, plus a VCR sized video processing unit with all the inputs that outputs over the DVI cable. It does not work unless the video processing unit is plugged in.
Image quality
It's bright, sharp, and colorful 720p but exhibits bad black crush, and relatively high black levels. Publications of the time also called this out, so I don't think it has to do with the age of my set. In fact the set appeared to be good as new, with great uniformity and no burn in.
Input lag (HDMI/480p), measured with a OSSC + 240fps highspeed camera
This tv has a relatively slow B2W transition of 10ms. So the input lag varies depending on whether you wait for the TV to reach a steady state (30ms) or measure the first moment that the screen responds to input (20ms).
How I measured: I used an OSSC outputting at 480p. The OSSC lights a LED the moment it starts transmitting the pixels of a white probe over a previously black background. Using a moderately fast high speed camera (Samsung S7, 240fps) you can measure the delay between the LED lighting and the probe appearing on the screen. Since the B2W transition takes some time, the probe gets brighter over 2-3 frames, giving the 20..30ms value reported above.
Side note: the OSSC measures lag in a somewhat unusual way: relative to the moment the probe pixels are sent over HDMI, rather than the start of the frame. So a probe in the middle of the screen or the bottom can actually appear to have less lag than the top. This is because the plasma takes a while to process the incoming image but then once painting begins it actually scans down the screen faster than the data is received, in effect catching up to the signal coming in over HDMI. BUT: since most dynamic sources (ie games) render the whole frame before sending it to the display, it makes more sense to measure relative to the very first pixel rendered (ie the upper corner). For those interested, the lower-corner lag is just 10ms for initial response and another 10 for steady state.
Performance: Deinterlacing using OSSC
Without going into too many details... The OSSC uses bob deinterlacing for zero added lag. This looks better when you add light-dark scanlines which masks the inherent "bob" blockiness of doubling each scanline. The result looks good but much darker on this TV, with very little flicker (probably because of the slow B2W transition).
Built-in TV deinterlacing using OSSC
The OSSC can instead send the interlaced signal to the tv and let it deinterlace. This also looks good; better than bob. The cost is lag - an extra 30ms, for a whopping 60ms of total lag. That's enough you can feel it. But for a RPG the result is excellent visuals.
Without the OSSC
The TV comes with 3 component inputs. If you plug directly into them the result is less pleasing than the OSSC. The upscaling is blockier and muddier. I've seen worse but it's disappointing for what was once such an expensive TV (msrp of $20,000!). I couldn't measure lag in this setup but I assume it's still about 60ms.
Without the remote
Don't get this TV without a remote. You cannot make any picture adjustments without it; all that remains is switching inputs and "changing volume" (but recall external speakers are required).
Image quality
It's bright, sharp, and colorful 720p but exhibits bad black crush, and relatively high black levels. Publications of the time also called this out, so I don't think it has to do with the age of my set. In fact the set appeared to be good as new, with great uniformity and no burn in.
Input lag (HDMI/480p), measured with a OSSC + 240fps highspeed camera
This tv has a relatively slow B2W transition of 10ms. So the input lag varies depending on whether you wait for the TV to reach a steady state (30ms) or measure the first moment that the screen responds to input (20ms).
How I measured: I used an OSSC outputting at 480p. The OSSC lights a LED the moment it starts transmitting the pixels of a white probe over a previously black background. Using a moderately fast high speed camera (Samsung S7, 240fps) you can measure the delay between the LED lighting and the probe appearing on the screen. Since the B2W transition takes some time, the probe gets brighter over 2-3 frames, giving the 20..30ms value reported above.
Side note: the OSSC measures lag in a somewhat unusual way: relative to the moment the probe pixels are sent over HDMI, rather than the start of the frame. So a probe in the middle of the screen or the bottom can actually appear to have less lag than the top. This is because the plasma takes a while to process the incoming image but then once painting begins it actually scans down the screen faster than the data is received, in effect catching up to the signal coming in over HDMI. BUT: since most dynamic sources (ie games) render the whole frame before sending it to the display, it makes more sense to measure relative to the very first pixel rendered (ie the upper corner). For those interested, the lower-corner lag is just 10ms for initial response and another 10 for steady state.
Performance: Deinterlacing using OSSC
Without going into too many details... The OSSC uses bob deinterlacing for zero added lag. This looks better when you add light-dark scanlines which masks the inherent "bob" blockiness of doubling each scanline. The result looks good but much darker on this TV, with very little flicker (probably because of the slow B2W transition).
Built-in TV deinterlacing using OSSC
The OSSC can instead send the interlaced signal to the tv and let it deinterlace. This also looks good; better than bob. The cost is lag - an extra 30ms, for a whopping 60ms of total lag. That's enough you can feel it. But for a RPG the result is excellent visuals.
Without the OSSC
The TV comes with 3 component inputs. If you plug directly into them the result is less pleasing than the OSSC. The upscaling is blockier and muddier. I've seen worse but it's disappointing for what was once such an expensive TV (msrp of $20,000!). I couldn't measure lag in this setup but I assume it's still about 60ms.
Without the remote
Don't get this TV without a remote. You cannot make any picture adjustments without it; all that remains is switching inputs and "changing volume" (but recall external speakers are required).
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