Anamorphic sizing no longer possible #167

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jarrettv opened this Issue Jan 11, 2017 · 6 comments

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@jarrettv

I tend to encode anamorphically to save retain quality in the vertical domain. However, the new UI doesn't allow you to do this. The "Use Anamorphic" option does nothing.

For example, choosing max width = 1280 and max height = 816, results in output of 1280x544, when I'd expect out to result in 1280x816.

@RandomEngy
Owner

You can use the "Manual" sizing option to accomplish this. Though I'm not getting the use case. Why do you only want to retain quality for vertical pixels?

@jarrettv

I'm trying to efficiently save space while retaining as much quality as possible. I've found if I go down to 720p that usually results in actual 544p (or less). So I choose to anamorphically encode my videos as a tradeoff between size-quality. This is only for h264 to h264. I keep original PAR when I do h264 to h265.

I've always read that the eye is more sensitive to vertical resolution than horizontal resolution. Perhaps this is legacy thinking from the DVD anamorphic days.

@RandomEngy
Owner

Hadn't heard about the horizontal/vertical difference in perception. Wasn't able to find anything about it in a search, can you link me to some of the studies?

@jarrettv

I can't find any studies either, but it was apparently common knowledge during the DVD re-encoding days.

https://www.google.com/?q=anamorphic+eyes+sensitive+vertical+resolution

@RandomEngy
Owner

I wonder if there's a credible source behind that, and what the magnitude of the effect is. I always thought that the anamorphic was mostly about allowing the DVD decoder to work with a set 720x480 resolution to simplify the implementation, then stretch out or in (to 850x480 or 640x480) to meet the aspect ratio of different sources.

@jarrettv

doom9 and hydrogenaudio are credible forums. But agree scientific study would be preferred. To my eyes, the anamorphic bitrate savings are a good tradeoff to:
*minor loss in horizontal resolution
*playback rescale

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