Freeview|HD Quality (Are all channels being upscaled?)

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ajobbins

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#21162 17-Apr-2008 16:50

I was in a DSE store today and so had a play with one of the DVB-T boxes they had hooked up to a HDTV. This was about 3pm today. First channel I looked at was 3, which had some cartoon playing (I think Sticky TV was on) and it looked really really good. Obviously it was upscaled but it really was sharp.

Next I had a look at 1 and 2. To me, these did not look any better than the SD transmission I get through Sky, (Dare I say it) maybe even worse.

Are TVNZ upscaling content at present? Sure didn't look like it...

openmedia

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#124448 17-Apr-2008 17:27

adamj: I was in a DSE store today and so had a play with one of the DVB-T boxes they had hooked up to a HDTV. This was about 3pm today. First channel I looked at was 3, which had some cartoon playing (I think Sticky TV was on) and it looked really really good. Obviously it was upscaled but it really was sharp.

Next I had a look at 1 and 2. To me, these did not look any better than the SD transmission I get through Sky, (Dare I say it) maybe even worse.

Are TVNZ upscaling content at present? Sure didn't look like it...

Ok now there are two types of upscalling, that done by the broadcaster and that performed by the box

See the Channel section at http://www.mythtv.co.nz/mythtv/digital-tv/ for details on what each channel is using

Now the TV's output might be set to either 720p or 1080i so any broadcaster signal will need to be scaled by the box to suit the TV.

Sadly the current box doesn't appear to have an auto switching mode where the signal sent to the TV matches the broadcast signal.

Generally known online as OpenMedia, now working for Red Hat APAC as a Technology Evangelist and Portfolio Architect. Still playing with MythTV and digital media on the side.

andrewcnz

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#124514 17-Apr-2008 20:13

Freeview HD on 1,2 and 3 (1080i via HDMI). Look's vastly better than sky tv's version of the same (my sky via component). This is on a full HD 46 inch Samsung. I difference is night and day even if the content is not true HD. Upscaled SD(read high bit rate) looks really good.

richms

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#124576 17-Apr-2008 23:52

Yes, but how does the box handle the upscale from 720p to 1080i? And then you have the deinterlace in the screen as well.

Not passing native resolution to the display is pretty lame IMO.

Richard rich.ms

mentalinc

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#124589 18-Apr-2008 07:18

richms: Yes, but how does the box handle the upscale from 720p to 1080i? And then you have the deinterlace in the screen as well.

Not passing native resolution to the display is pretty lame IMO.

According to this http://nz.youtube.com/watch?v=Z-JXfyvlPh0 it is actually DOWNscaling from 720p to 1080i

They put the video in order as follows
1080p
720p
1080i

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richms

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#124702 18-Apr-2008 11:58

Not if the source is in film mode, since it will be 24 frames, in the states they get a nice simple 3:2 ratio to get that up to 60 fields which is quick and easy to de-mangle at the display end by putting the right fields together and throwing the extra ones out (called reverse telecine). - so using 1080i there is lossless as it is for movies on bluray.

With the 50Hz stuff we get here, who knows really. They could either be doing the old trick of speeding it up, or they could be systems converting the 60Hz stuff to 50 like they do with ntsc to pal conversion. I cant tell if theres a speed up and have not tried frame by frame thru anything on 3 to compare with a torrent version of the same show from the states which has being converted to 24 frames.

The only big problem is when stuff comes from a video camera and there is motion between the fields, thats what causes the blur effect, but the deinterlacing on displays will usually hide it since its not obvious on a moving object and you only get to see the blur happening if you deinterlace and then pause the resulting deinterlaced signal. Most video cameras have progressive mode where they will fake film mode too or else record 30 frames and convert that into 60 fields.

Richard rich.ms