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Author Topic: With all the recent TV improvements ...  (Read 1733 times)

InflatableMouse

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With all the recent TV improvements ...
« on: May 23, 2013, 02:38:13 pm »

Is there any chance we'll see decryption for encrypted channels for those poor Europeans like myself? It was low on the list a while back but with all the recent improvements scrapped off that list I figured this must be getting closer to the top  :-*.
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MrHaugen

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Re: With all the recent TV improvements ...
« Reply #1 on: May 24, 2013, 10:20:28 am »

I gave up on this subject one year ago :( Not that it would not be great for some. But I've completely moved away from regular broadcasting. I am so used to seeing things when I want with the quality I want. Not to mention commercial free. Aaaah!

A small question. Whats up with the video broadcast seems to go a notch or two faster than the same content I download?!? It almost makes me sea sick or something. I can't stand it. Is it some NTSC vs PAL and more/less frames or something? It's the same for my TV decoder, as well as my parents decoder. I've tried googling it, but have found nothing so far. Sorry for the small hijack....
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glynor

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Re: With all the recent TV improvements ...
« Reply #2 on: May 24, 2013, 12:50:21 pm »

Probably a PAL vs NTSC thing, but I'm not sure from your description.

Standard framerates in NTSC-land are 30/60.
Standard framerates in PAL-land are 25/50.
Film is roughly 24fps.

The way they "convert" from NTSC to PAL when they are lazy/underpaid/uncaring is by just doing a straight-conversion.  In other words, playing what was designed to play at 30fps (29.97 to be precise) at 25fps instead, altering playback speed to compensate.  This is awful and is probably not what is happening here, because it would be really bad and it would be "slower" (roughly 83% of the original speed) not "faster".  The proper way is to use a complex pulldown pattern to convert, though in practice most content that makes it "across the pond" was originally shot at 24p, so they usually just use the film methodology (or they reverse telecine it to 24p and then use the film methodology).

The way they convert film (24p) for PAL is almost always just to play footage that was shot at 24fps at 25fps instead.  This means it will play ever-so-slightly "in fast forward" (4%).  The proper way is to insert repeating frames as needed using a complex pulldown pattern (2:2:2:2:2:2:2:2:2:2:2:3), but since the framerates are so close (and pulldown is hardware-expensive and complicated), this is not commonly done.  Of course, using a pulldown pattern introduces telecine judder (the last frame in the pattern plays for 1/3rd longer than the others), but this difference is less distracting in many cases than the audio speedup pitch change.

Of course, if you grew up in PAL land, you grew up all thinking we speak a quarter tone higher-pitched than we actually do.  I wonder how Darth Vader sounded there?

More info:
http://en.wikipedia.org/wiki/Telecine
http://en.wikipedia.org/wiki/Television_standards_conversion

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Hendrik

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Re: With all the recent TV improvements ...
« Reply #3 on: May 24, 2013, 12:54:33 pm »

You can actually speed up audio without pitch changing it. :p
But i wouldn't know, around here everything is dubbed, and i certainly do hope they are smart enough to do that after converting to PAL.
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glynor

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Re: With all the recent TV improvements ...
« Reply #4 on: May 24, 2013, 12:58:53 pm »

You can actually speed up audio without pitch changing it. :p

That is true, now.  Though pitch shifters (timescale accurate ones, anyway) are a relatively recent invention, and are still not widely used.

Opinions differ on whether the "right way" is to use 2:2:2:2:2:2:2:2:2:2:2:3 (introducing judder) or using a pitch shifter (introducing audio artifacts).  The right answer now probably depends on the subject at hand.

Of course, the alternative is to do optical flow on the footage and actually make the proper number of frames.  This, of course, takes forever (even with render farms) for feature length films and softens the footage.  Though, a little softening might not matter if you shoot at 5k and deliver at 1080p.  Doing optical flow on 5k 10-bit source footage though is...  Not an insignificant computational challenge.
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