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28th September 2015, 03:48 | #1 | Link |
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Optimal 480p resolution for HEVC
480p for 16:9 is 853.33x480. right?
Since a pixel should be a whole number, ppl use 854 or 852 or 848 for width. Ppl use 852x480 to get the width dividable by 4. And 848x480 to it dividable by 16. I would like to know how HEVC behaves among those 3 resolution. (854x480, 852x480, 848x480) Sure it supports all 3... But what are the impacts of encoding... Regarding the resolution factors and image stretch and A/R deviations when resizing, what could be the optimal for HEVC In HEVC, is that, dividable by 4 and 16 factors are less important than in AVC? ! |
28th September 2015, 14:23 | #2 | Link |
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x265 pads the video out to min-cu size, generally 8x8 but can be set higher. The visual compression difference of any of the three sizes will probably be completely unnoticeable. (Frankly, the aspect ratio differences will also probably be unnoticeable in casual viewing.) Just use whatever you prefer.
HEVC won't gain you much at all at that resolution though; it barely even gains much at 1080p. It's tremendously better than x264 at 4K and up, but that's worlds away from 480p. Give it a shot, though, maybe your video works better. |
28th September 2015, 14:52 | #3 | Link |
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Typical process on DVD source is to crop 8 pixels on left and right side, and then resize to 854x480.
If you are looking for optimal width then you can try different cropping. (For example, 10 pixels on each side and then 848x480, etc
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28th September 2015, 16:15 | #4 | Link | |
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Quote:
Mod16 is preferable for ALL codecs.
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Czech DivX/XviD discussion club Last edited by HarryM; 28th September 2015 at 16:19. |
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28th September 2015, 19:49 | #6 | Link | ||
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Quote:
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Don't say such things. It is hardly true for anything decent since x264 and thanks to myths like this, people ruin their videos by using wrong ARs, overcropping and such. The benefits of using mod16 resolution are basically zero. If you disagree, try to make a comparison of two encodes where rounding the resolution to mod16 would be improving quality! (And that would still ignore the issue that forcing mod16 harms quality in the first place by requiring resampling and/or overcrop.) Last edited by mandarinka; 28th September 2015 at 19:52. |
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29th September 2015, 12:32 | #8 | Link |
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I recently went through some of my old 720x480 (16:9 DAR) MPEG-2 disc sources and have re-encoded them to AVClossless at 856x480 pixels (ie: mod-8)
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Last edited by SeeMoreDigital; 2nd October 2015 at 17:33. Reason: Corrected AVClossless resolution |
2nd October 2015, 17:28 | #9 | Link | |
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Now that non-square pixel support is pretty well universal, I'm a fan of just cropping to active image area and keeping all the pixels and the SAR. There's no benefit to throwing pixels out or to creating new ones. I think Mod-4 is pretty well universally compatible today in released decoders. The only exception I can think of will have that fixed in a mandatory firmware update within a week. |
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5th October 2015, 04:12 | #10 | Link |
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Most time when we are talking about non-anamorphic, or mod XX, we are talking about compatibilities.
For a "normal" player, these features are all well supported, and keep the original resolution + crop only the margin + mod 4 + anamorphic should be a very good option. However when dealing with buggy decoders (who may crash on non mod 8/16), buggy subtitle filters (who may ignore ARs), extra care should be taken when making decision. You never know what soft/hardware user is gonna use. |
5th October 2015, 18:46 | #11 | Link |
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Again, this is HEVC. All of that is much less likely on something that can play HEVC. I also prefer encoding the original pixels if possible.
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13th October 2015, 19:57 | #13 | Link |
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Well, except HEVC player = recently updated player. I suspect most HEVC decoding is being doing in players/OSes/SoCs that already had anamorphic nailed. I certainly feel more comfortable that anamorphic HEVC will work on an arbitrary HEVC compatible player than anamorphic HEVC will work on a arbitrary compatible H.264 player.
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5th January 2016, 20:28 | #14 | Link | |
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However, 712x 40/33 ~ 863.... Remember that DVD frames are 720, but mpeg frames are ~704 in fact 704x 40/33 = 853.333 |
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9th January 2016, 13:34 | #15 | Link |
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I tested x264 codec and non-mod16 and mod16 resolution coding... in many scenarios.... and my conclusion is, that non-mod16 resolution is generally possible, but with significant filesize penalty - plus +2-4% on bitrate/framepixel.
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10th January 2016, 09:29 | #16 | Link | |
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May be I'm wrong, but with a bit rate of 10 MBit/s and a resolution of 1920x1080 one would have a bit/framepixel value of 10000000 / 2073600 = 4.8225308641975308641975308641975 bit/framepixel. 4% of that would be 0.1929012345679012345679012345679 bit/frame pixel, which would be 400 bit/frame. Given a 3hr ( = 240min = 14400 sec) movie with a frame rate of 24fps we would have 345 600 (= 14400*24) frames and thus a file increase of (345 600*400) 138 240 000 bit = 17 280 000 byte = 16.4794921875 MB. Normal file size would be (10MBit/s = 10 000 000 = 1 250 000 byte/s =) 1.1920928955078125 MB/s time 14400 sec = 17 166.1376953125 MB. Less than 1% file increase doesn't sound that significant to me,... |
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10th January 2016, 11:06 | #17 | Link |
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...Is the hour? It is 80 minutes.
A good movie is 2 hours, and this 3 hours are 240 minutes If its +2-4% on bitrate/framepixel, its +2-4% on bitrate or size as well. I like numbers, but there are too many in your post. what is the distance of Centauri? 4Ly, 480 days in a year, 32 hours in a day, 80 mins in a hour, 80 secs in a min.....very big! The difference exist, but is very smaller mod16xmod8 is still very good If you really seek for total compatibly and universal rendering should use mod64xmod64. that gives few res available for 4:3 256x192 and multiples for 16:9 1024x576 and multiples for 2.35 2560x1088 and multiples. Last edited by movmasty; 10th January 2016 at 13:49. |
10th January 2016, 11:08 | #18 | Link | |
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Quote:
And I'm pretty sure he meant just 4% increase in bitrate or bpp. Compatibility? What kind of decoder can't decode 720p because it's not mod64? Last edited by vivan; 10th January 2016 at 11:11. |
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480p, hevc, x265 |
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