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post #61 of 62 Old 06-23-2014, 11:11 PM
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Originally Posted by sneals2000 View Post
May be based on what image you run on your Dreambox (I'm running OpenPli) - but I was quoting from the experience of using my DM800HD (non-SE).

I only get the option to set the frame rate of the output to a fixed 60Hz when I select 720p as the resolution. If I select one of the other resolutions I don't get that option - presumably it passes through the broadcast frame rate instead. My TV accepts 480/60i, 480/60p, 576/50i, 576/50p, 720/50p, 720/60p, 1080/50i, 1080/60i, 1080/24p, 1080/50p and 1080/60p inputs via HDMI - and correctly reports this via EDID so it's not an issue with my TV not accepting 1080/60i etc.

My guess was that it was easier to frame-rate convert a de-interlaced or native progressive image than an interlaced one.

Thinking about it you can't frame repeat an interlaced image - as if there was motion between fields within the frame (as would be the case with native interlaced content) you'd have issues of repeated motion, and field repetition is tricky. To do it properly you'd have to de-interlace 1080/50i to 1080/50p and then frame repeat to 1080/60p and then re-interlace to 1080/60i. Much easier to de-interlace and scale (if non-720p) to 720/50p and then frame repeat to 720/60p.

(My experience of cheap US DVD players that did 50<->60 conversion was that they often dropped to 25/30Hz motion when frame rate converting - presumably by doing a crude field-drop - to allow them to frame repeat interlaced content without motion repetition)

BTW - if you're worried about the resolution loss from de-interlacing 1080/50i to 720/60p - I wouldn't worry about that. The frame rate conversion will be far worse a quality drop.

Other Dreambox models may well do a 1080/60p output these days - my DM800HD doesn't.
I just tried a DM800se with F8500, I can switch between all kind of resolutions 720/1080 i/p using either 50Hz/60Hz no issues
I find it hard to believe that 800HD is limited
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post #62 of 62 Old 06-24-2014, 01:58 AM
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Originally Posted by anis_ber View Post
I just tried a DM800se with F8500, I can switch between all kind of resolutions 720/1080 i/p using either 50Hz/60Hz no issues
I find it hard to believe that 800HD is limited
What image are you using on the 800SE? As I said I'm running OpenPli.

Though - to be honest - it's of little real importance. The SoCs that Dream use for the boxes won't be capable of any half-way-decent frame-rate conversion. Nothing at the consumer price point is. To do the job properly you really need something like the Alchemist PhC - which is what broadcasters use to standards convert. (There are a LOT of them converting the 1080/60i Rio World Cup footage to 1080/50i for Europe/Asia/Australasia etc. and even they have visible conversion artefacts).

If you care enough about picture quality to have an OLED TV you surely care enough about picture quality not to watch a terrible 50/60Hz conversion? Native or not at all surely?

Last edited by sneals2000; 06-24-2014 at 03:26 AM.
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