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Old 26th September 2015, 12:59   #161  |  Link
Music Fan
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Here are the results : I encoded in 720*480 @ 25p, added pulldown with DGpulldown (I checked the line 25 --> 29.97) and made a dvd with Muxman.
Tested on 3 players all set on 1080p : none displayed 50 hz !
Oppo and Pioneer output 60p, Sony outputs 24p !?

edit : if I disable 24p in Sony's setup (no instead of auto, there is not yes or force), it outputs 60p.
I can force 50p in Oppo's setup (which calls it PAL) ; that's probably the best way to look this kind of dvd but curiously I didn't notice difference compared to 60p output (when Multi-system is selected in Oppo's setup).

Last edited by Music Fan; 26th September 2015 at 13:39.
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Old 26th September 2015, 13:21   #162  |  Link
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Interesting. Not much smartness then.
It seems like the Sony applies standard IVTC with decimation.
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Old 26th September 2015, 13:32   #163  |  Link
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I don't know what it does but 24p has no sense, that should be 50 or 60p.
I edited my previous post to add some informations.
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Old 26th September 2015, 13:50   #164  |  Link
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Hmmm.... Isn't your 25p source a speed-up 24 film?
Maybe the Sony is smarter than we thought... ;-)

At the end, the answer may again be: "It depends on the player".
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Old 26th September 2015, 14:21   #165  |  Link
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Quote:
Originally Posted by Music Fan View Post
Here are the results : I encoded in 720*480 @ 25p, added pulldown with DGpulldown (I checked the line 25 --> 29.97) and made a dvd with Muxman.
Tested on 3 players all set on 1080p : none displayed 50 hz !
Oppo and Pioneer output 60p, Sony outputs 24p !?

edit : if I disable 24p in Sony's setup (no instead of auto, there is not yes or force), it outputs 60p.
I can force 50p in Oppo's setup (which calls it PAL) ; that's probably the best way to look this kind of dvd but curiously I didn't notice difference compared to 60p output (when Multi-system is selected in Oppo's setup).
is this like soft telecine?

broadcast doesn't support this AFAIK.
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Old 26th September 2015, 14:57   #166  |  Link
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Hmmm.... Isn't your 25p source a speed-up 24 film?
Yes.

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Maybe the Sony is smarter than we thought... ;-)
No because it was encoded in 25p (with assumefps(25) in the script) and nothing can tell the player that the orignal speed was 24p, even the mpeg-2 encoder has no way to know it.
The script ouputs the same kind of signal than if I had de-interlaced 50i to 25p.
If I had done changefps(25) instead of assumefps(25), in this case ok, a frame would be duplicated and the player could detect it, but it's not what I did.
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Old 26th September 2015, 14:59   #167  |  Link
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is this like soft telecine?
Yes, DGPulldown don't re-encode, it only add flags.
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Old 26th September 2015, 15:12   #168  |  Link
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Yes.


No because it was encoded in 25p (with assumefps(25) in the script) and nothing can tell the player that the orignal speed was 24p, even the mpeg-2 encoder has no way to know it.
The script ouputs the same kind of signal than if I had de-interlaced 50i to 25p.
If I had done changefps(25) instead of assumefps(25), in this case ok, a frame would be duplicated and the player could detect it, but it's not what I did.
I can only guess that the Sony player has seen the flags and then defaulted straight to 24, assuming that this is the most likely case. Just speculating.
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Old 26th September 2015, 15:16   #169  |  Link
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I also believe this.
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Old 26th September 2015, 15:22   #170  |  Link
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Did you inspect the .ifo and .vob with e.g. ifoedit? Anything unusual? These contain also instructions for the playback.

Edit:
Just as a sidenote: When I do a 2:1:1:1:1 hard-pulldown (Changefps(30)) in avisynth and decimate it with tdecimate() without specifying the framerate explicitly it also defaults to 24 fps. In order to get 25fps output I need to specify tdecimate(mode=2,rate=25), or fdecimate(rate=25).

Last edited by Sharc; 26th September 2015 at 15:53.
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Old 26th September 2015, 17:03   #171  |  Link
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Using interlaced chroma sampling is exactly the same as not doing anything special to the chroma, unless we're talking about one of those formats with oddball interlaced chroma sampling. (DV is one of them, I think?)
It's not the same, I am not talking about chroma placement (like DV vs MPEG2). It's about how the chroma was downsampled from (usually) 4:2:2 to 4:2:0 for DVD encoding. I'm sure you know this can be done in two ways

ConvertToYV12(interlaced=false)
and
ConvertToYV12(interlaced=true).

For a progressive video, one would use interlaced=false, right? The problem is, if you encode (or rather flag) the video interlaced the player might do something like this to upsample the chroma for playback:

ConvertToYUY2(interlaced=true)

Now that will result in the CUE (chroma upsampling error) if you used ConvertToYV12(interlaced=false) rather than ConvertToYV12(interlaced=true) for downsampling to 4:2:0.



Quote:
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(Also, I just did a search on CUE and the first few results were from like 2001. How is this still a concern in 2015?)
At that time it was a concern because many hardware players were simply lacking a progressive chroma upsampling method. They used an interlaced one, no matter what.

It is potentially still a concern today in the case described above, but this time it's not the hardware's fault but user error.


CUE (down: p; up: i)


Correct (down: p; up: p)


Also correct (down: i; up: i)

Last edited by TheSkiller; 26th September 2015 at 20:19.
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Old 27th September 2015, 05:41   #172  |  Link
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It's not the same, I am not talking about chroma placement (like DV vs MPEG2).
Neither was I—I was pointing out that if we assume that we can just Weave() together fields and have correct chroma siting (this is true of the "standard" 4:2:0 interlaced chroma siting), then there's nothing special that needs to be done if we can assume the playback setup isn't completely broken.

Okay, that's actually a huge bunch of "if"s chained together and we all know playback setups can be broken in very creative ways, but honestly I think the solution should be to fix them (or at least get people to stop buying shitty DVD players etc.) rather than messing with things on the mastering side.

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It's about how the chroma was downsampled from (usually) 4:2:2 to 4:2:0 for DVD encoding. [snip] Now that will result in the CUE (chroma upsampling error) if you used ConvertToYV12(interlaced=false) rather than ConvertToYV12(interlaced=true) for downsampling to 4:2:0.
My ten minutes of Googling led me to believe that the term "CUE" is meant specifically for the problem of upscaling the chroma fields with the wrong offsets, not for a mismatch of interlaced/progressive resampling. The latter's not as big a problem and can be worked around on the mastering end just by using a low-pass filter prior to interlacing (or widening the support of the downscaling filter when converting from 4:2:2/4:4:4/RGB to 4:2:0).

A playback setup is not required to be able to detect and reverse pulldown, so this application of a low-pass filter is the only way to guarantee that the chroma will correctly render on playback, regardless of whether the content is really interlaced (50/60 temporally distinct fields) or pulled-down. In practice it's probably safe to assume some sort of field matching will be used and that progressive chroma upsampling is done after all the deinterlacing and field matching nonsense, so you could just ignore this issue entirely. If it still uses interlaced chroma upsampling after deinterlacing or field matching, then that obviously falls under the category of "your setup is broken so we won't support it".
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Last edited by colours; 27th September 2015 at 05:52.
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Old 27th September 2015, 12:09   #173  |  Link
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And how to apply a low-pass filter with Avisynth ?
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Old 27th September 2015, 12:44   #174  |  Link
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blur(1).sharpen(0.3).blur(1).sharpen(0.3)
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Old 27th September 2015, 14:45   #175  |  Link
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Quote:
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Neither was I—I was pointing out that if we assume that we can just Weave() together fields and have correct chroma siting (this is true of the "standard" 4:2:0 interlaced chroma siting), then there's nothing special that needs to be done if we can assume the playback setup isn't completely broken.
I agree, nothing needs to be done.


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In practice it's probably safe to assume some sort of field matching will be used and that progressive chroma upsampling is done after all the deinterlacing and field matching nonsense, so you could just ignore this issue entirely. If it still uses interlaced chroma upsampling after deinterlacing or field matching, then that obviously falls under the category of "your setup is broken so we won't support it".
Yes, but if you are using a traditional plain ol DVD-player without any progressive scan, just Scart, the player wouldn't do anything more sophisticated than ConvertToYUY2/RGB(interlaced=true) whenever the stream is flagged as interlaced.
Now my point is, the player is not doing anything wrong there, really. Whenever you put something non-interlaced on a DVD and yet flag it interlaced, you should downsample the chroma to 4:2:0 the "interlaced way". I'm rather sure in the end that's probably almost the same as applying a vertical low-pass on the chroma, so we kind of agree that something needs to be done.

Last edited by TheSkiller; 27th September 2015 at 14:47.
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Old 27th September 2015, 15:30   #176  |  Link
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blur(1).sharpen(0.3).blur(1).sharpen(0.3)
Ok, and why does it act as low-pass ?
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Old 27th September 2015, 16:18   #177  |  Link
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Ask Didee, it's his idea and it works.
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Old 27th September 2015, 16:35   #178  |  Link
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blur() reduces details and sharp transitions by removing high frequencies = lowpass filtering

You could also downscale (and then upscale) the picture. Scaling applies a lowpass filter in order to prevent aliasing.
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Old 27th September 2015, 17:26   #179  |  Link
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Whenever you put something non-interlaced on a DVD and yet flag it interlaced, you should downsample the chroma to 4:2:0 the "interlaced way". I'm rather sure in the end that's probably almost the same as applying a vertical low-pass on the chroma, so we kind of agree that something needs to be done.
I'm not entirely convinced by this, actually. Going by the very same pictures you uploaded, it's clear that even with the stronger colour fringes, the p-down/i-up pic looks less bad than the i-down/i-up pic.

Let's disregard the idea of using a low-pass filter for the time being. By using interlaced downscaling, there would be two steps causing aliasing in the whole chain (both downscaling and upscaling), whereas with progressive downscaling, the only step that causes aliasing is the interlaced upscaling step. There's no obvious reason to believe that the aliasing caused by interlaced upscaling and by interlaced downscaling should magically cancel out, so progressive downscaling should be preferred.

With a low-pass filter applied, all of this becomes moot if we use a sinc filter (zero aliasing in either step!), but since we don't actually use sinc filters for low-pass filtering or resampling (lolringing + lolslow), to minimise aliasing we should still use progressive downscaling. (Also, we can combine the resampling and low-pass filtering steps into one by adjusting Dither_resize16's fv parameter.)

I think there might be a better way of downscaling than either normal progressive downscaling or interlaced downscaling if we know that it'll be interlace-upscaled later on, but I'm a bit too busy to work out the details at the moment.
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Old 28th September 2015, 10:48   #180  |  Link
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I'm not entirely convinced by this, actually. Going by the very same pictures you uploaded, it's clear that even with the stronger colour fringes, the p-down/i-up pic looks less bad than the i-down/i-up pic.
OK, those lines I drew in Paint aren't very good at showing the aliasing. So I re-did the test with this chroma zone plate.


down: p; up: i


down: p; up: p


down: i; up: i
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