Noob question: Upscaling -whats the big deal ?

Mike 1972

(Wasnt sure which subforum to post this in so Mods please move if/as necessary)

In other threads Ive read about proposals for the RTE HD channel(s) to carry upscaled SD content.

Ive also seen DVD players in shop which make a big deal about their ability to upscale ordinary (480 or 576) DVD's to HD

Thing is dont all LCD and Plasma TV's contain upscaling circuitry anyway out of necessity in order to match the content to the native resolution of the display ?

What (if any) benefit derives from upscaling the content earlier in the chain and indeed whats the big deal regarding upscaling anyway. If content was originally produced/recorded/transmitted at a low resolution all that fine detail is surely going to be lost permanently and upscaling it is akin to attempting to make the poverbial silk purse out of a sows ear ?

Or am I missing something here

watty

some Tvs don't switch resolution on the fly without changing channel.

So if you are transmitting "some" HD, it's simpler to transmit fake HD (upscaled).

It's likely that RTE would have a better quality "upscale" (Up Conversion) than in a Domestic HDTV and use a 720 x 576 source, thus picture quality on the artificial 1440 x1080i will be better than your own HDTV or set-box upscaling from 544 x576.

If the screen of HDTV is natively 1366 x 768 or 1920 x 1080, then up scaling has to happen somewhere.

Not all TVs upscale with equal quality.

Not all SD source started as SD. HD source "properly" converted to SD, is higher quality. Compare #2 and #5, Simulation of SD source poorly upscaled, with HD original downscaled to DVD or SD tape and SD transmission and then high quality upscale.

Quick attempt at simulations from clip out of HDTV test card.

1 is HD Transmitted as HD

2 to 5 are Transmitted as SD (approx 544 x 576), Source and conversion explained. or 4 & 5 upscalled at RTE and transmitted as HD.

All 5 are simulated what a 1920 x 1080 native pixel HDTV would show.

HD Image

Simple upscale from SD (Cheap HDTV)


Simple upscale from Advanced Down conversion to SD (i.e. DVD or video antialiased from Film) (Cheap HDTV)

Advanced upscale from SD, i.e. RTE end upscale, or high quality HDTV

Advanced upscale from Advanced Down conversion to SD i.e. RTE end upscale or Quality HDTV from 720 source that was antialised from HD (or Film) originally.

Mike 1972

Thanks for the pretty detailed answer but what about those "upscaling DVD players" ?

Theyre obviously not going to have broadcast quality upscaling circuitry but are they likely to be significantly better than whats in the TV already ?

watty

It depends on the quality of the TV and the quality of the DVD player.

Since almost no such DVD player has a spec, and only high end TV has a Spec, you can't tell till you compare SCART and HMDI.

Note that the real reason for Progressive or HDMI Up-scalling (to 720p, not 1080i) DVD players is for NTSC areas, i.e. 30fps 60Hz interlace.
You can't sensibly show interlaced 24fps film source on 30fps 60Hz Interlace. you get Pull down artefacts.

With 576i (50 fields/ 25 fps) there is no advantage to progressive DVD as any de-interlacer can PERFECTLY convert Interlaced Film Source to Progressive if it's "PAL" region (all decent De-Interlacers /Upscalers in TVs have Telecine auto-detect). Usually with the 24fps to 25fps speedup, the audio is remastered to reduce the pitch by 25/24ths to keep pitch true, so playback PAL regions at 24fps and 1080p24 makes the audio pitch wrong. You can playback US region DVD at 1080p24 on suitable DVD and TV, but the source MPEG2 is only 480lines compared with 567 lines for PAL regions.

So PAL region DVD played back interlaced is higher quality than NTSC region Progressive, as there is 576/480 more vertical resolution and the same horizontal resolution.

I suspect only decent BD players do a good job of DVD upscaling and that Upscaling (HDMI) output DVD player is only of value in North American/Japan.

There is ONE advantage of a DVD player here that can do Progressive (rather than upscale). It will have a VGA connector, as SCART doesn't support either HD or Progressive like Component does (deliberate choice, it could, but Progressive is pointless in SCART 576i world and no encryption, most boxes (DVD or Satellite/DTT/Cable) for Europe only do SD on component, HD with HDCP on HDMI). Then if you have a PC monitor that does 800 x 600 @ 50Hz (few will, but none will do 576i), you can have it on DVD player. I think this is pointless unless its for an Office and you want to avoid a TV licence.


576i, 1080i (50Hz, 25fps) (Europe)


480i, 1080i (60Hz, 30fps) (North America, Japan)


Note that Artefacts on 480i and 1080i 30fps / 60 Field/s only apply to moving source. A static image is perfect, and on all systems a static or slow moving scene has SAME quality on 1080i and 1080p. 1080p is NOT a higher vertical or horizontal resolution. It has about 50% more temporal resolution.

Not entirely accurate:
http://en.wikipedia.org/wiki/Telecine#3:2_pulldown
http://en.wikipedia.org/wiki/Television_standards_conversion
http://en.wikipedia.org/wiki/576i

watty

Sometimes an upscaled DVD is nearly indistinguishable from a BD (Bluray)
http://www.reghardware.com/2010/11/25/bluray_disc_quality_difference/

Why?
Mathematically if a DVD is anti-aliased down from a 1440 x 1152 film scan to 720 x 576 the quality is almost the same as 1440 x 1152 film scan re-sampled to 1920 x 1080.

In reality various higher resolutions are used to scan film and then eventually down sample to 720 x 576 (or 720 x 480 North America/Japan).

You need really good film masters scanned at least 3840 x 2160 anti-aliased to BD 1920 x 1080, older film may not be good enough.

They are simply transferring the scanned digital master made for DVD resampled in most cases to 1920 x 1080 for BD. Only the better quality releases are going to film and making a new scan.

DVDs also vary greatly in quality. Good DVDs will upscale as per #5 image above. Sadly, if they simply up convert the DVD master, the BD looks like this too



But if the source is not rescanned at least 3840 x 2160 anti-aliased to BD 1920 x 1080, your BD version is #1


(I can't show you 1920 x 1080 anti-aliased from scan of 3840 x 2160 from Film as I don't have the 35mm 6cm colour slide!)




if the DVD or BD is upscalled from video tape or scan made for Laser vision you get

Souriau

I am looking for resolution and how much bit are for each.
576i
576p
750p
1080i
1080p
I once saw it somewhere on this forum but can't find it
can anyone point me to that link or tell me again

TIA

icdg

we don't drag up old threads.

watty

Souriau wrote: »

I am looking for resolution and how much bit are for each.
576i
576p
750p
1080i
1080p
I once saw it somewhere on this forum but can't find it
can anyone point me to that link or tell me again

TIA

An impossible question to answer as it depends on

• Perception of quality aimed for
• Kind of source material (amount of movement x detail, grass and sea foam are "bad")
• Type of Codec (MPEG2, MPEG4 etc)
• How well implemented it is
• CBR vs VBR vs Statistically Multiplexed VBR
• Horizontal Resolution (can be 384, 544, 704 or 720 for 576i, can be 960, 1440 or 1920 for 1080i or 1080p)

Disc (Bluray far more than DVD) typically is more than Satellite which is typically more than Terrestrial. Often cable is lowest, but not always. Satellite has the highest for Broadcast on "good" channels" and also the worst on "cheap" channels.

Souriau

OK, let just say for UK PAL TV 50hz
720 x 576i
720 x 576p
1280 x 720p
1440 x 1080i
1920 x 1080i
1920 x 1080p

I understand that the bit requitements can go up or down depends on the full picture change or just a small change.
So just let say, a full screen update
or the max for each resolution setting above

TIA

watty

Sorry, it's meaningless without

• Perception of quality aimed for
• Kind of source material (amount of movement x detail, grass and sea foam are "bad")
• Type of Codec (MPEG2, MPEG4 etc)
• How well implemented it is
• CBR vs VBR vs Statistically Multiplexed VBR

For 720 x 576i it can be as low as average 0.5Mbps on a peak 2Mbps VBR stat mux MPEG4. Or as high as 9Mbps MPEG2 on DVD. Broadcast HD can be as low as 2Mbps and BD (bluray) as high as 21Mbps (MPEG4). Excluding audio or other streams.

50Hz 576p is pointless. Its usually 24FPS film source frame doubled.
1080p 50Hz is either 24FPS film source frame doubled, de-interlaced upscaled 576i or de-interlaced 1080i or Computer graphics.

I understand that the bit requitements can go up or down depends on the full picture change or just a small change.
So just let say, a full screen update

It doesn't work like that. What are trying to achieve? The whole point of Digital vs analogue is NOT better quality but the ability to tailor the encoding to suit your requirements. Analogue takes a fixed amount of space.

All the compression schemes rely on a MIX of scene content (small amounts of major change, lots of gradual changes) and encode over a variable number of video frames.

Also "PAL" as such doesn't exist. Pal source is a fixed 576i with a specified ratio of luminance to chrominance sampling. Digital sources may be a higher ratio such as 4:2:2 to allow higher quality editing.

HD needs about x4 SD, for SAME codec type and quality. MPEG4 about 1/2 or less of MPEG2 for same perceived quality and input resolution.

Souriau

OK, planning to get BD burner and burn some of fav TV show on disc for future viewing
DVD is just 720x576i in HQ mode and at 4.7gb, I get 1.5 hours recording
so maybe I get to go up to 720p for allowing me to put many hours on 1 BD
will have HD input quality to burn on BD
1440x1080i, would that take up more space than 1280x720p?

TIA

watty

Best quality is to NEVER re-encode. But just convert from Transport Stream to Program stream.

Changing resolution dramatically hurts quality on Interlaced content (virtually all Broadcast in UK and all in Ireland). Re-encoding unless you make the file BIGGER hurts quality.

The big advantage of Digital over analogue is ability to record the "live" signal and play that back exactly.

You do need a PC with Digital Tuner cards (satellite) and/or USB sticks (DTT) and some free tools to convert from TS recording on HDD to PS on BD. It's very difficult to impossible with "Appliance" PVRs to burn to disc unless that is built in.

http://www.techtir.ie/blog/watty/mheg5-on-xp
Red button Sport Multiscreen now works!

The PC can live in a different room and feed HDMI to TV over 2 x CAT5. We also have USB extender, IR remote over CAT5 and audio over Cat5
http://www.techtir.ie/howto/hdmi-via-cat5-cable

You should have started a new thread: How do I record on BD from Digital TV? The Bitrate questions are irrelevant as you can only have whatever they are for best quality (Stream conversion, no re-encoding), less bit rate for much poorer quality and much higher bitrate if you re-encode at the same quality.

icdg

I really did mean to close this...