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29th December 2009, 05:53 | #1 | Link |
ekTOMBE STUDIOS
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non mod 16 cropping or black bars : which is worst and why?
As the title says.
i know the ideal is crop black bars and leave the frame on mod 16 size. But some times is not possible without cropping image. Well i DONT want crop the image. Sometimes that can't be done without breaking one of these two rules: A) crop black bars and leave a non mod 16 picture (some times the picture has tiny little bars of 2 or 3 pixels on the sides or up and down). B) Leave the black bars (rarely those black bars are mod 16 width). I know both choises are not reccomended, but wich one is preferable? (in therms of compression quality/efficience) Thanks
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29th December 2009, 07:58 | #3 | Link |
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So encoding at non Mod16 is not an issue with x264 or is it more the playback end that can causes issues with non Mod16 encodes?
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A Man Eating Duck Last edited by AMED; 29th December 2009 at 08:00. Reason: beer related typos |
29th December 2009, 14:10 | #5 | Link |
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Search is always your friend:
http://forum.doom9.org/showthread.ph...ighlight=mod16 <-- short and precise answer http://forum.doom9.org/showthread.ph...ighlight=mod16 <-- very informative thread |
30th December 2009, 19:03 | #8 | Link | |
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Don't know about xvid, but Divx supports non-mod16:
Quote:
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31st December 2009, 21:56 | #10 | Link |
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If i remember correctly xvid required width and height multiple of 4. I think it was because of some conversions between yv12 and yuv2 and other color spaces it supported. Huffyuv had the same requirements so I personally got used to cropping to multiples of 4.
As for x264, i think internally just duplicates the last line(s) to reach a multiple of 16. In some cases (mpc-hc with dxva decoding of 1920x1080 on 1920x1200 screen) I could see those duplicated lines and it was a bit annoying. To answer the original question, I always crop the black lines out unless the destination is some device that only accepts some fixed resolutions. I also try to keep both width and height multiples of 16, 8 or in worst case multiples of 4. A couple of lines cut out to have a multiple of 4 at least, won't be noticeable. |
4th January 2010, 15:48 | #11 | Link |
ekTOMBE STUDIOS
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Location: Cuba
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So, the decoder must be capable of hiding the added lines?
But if any tool checks the videos (for example the mediainfo library) it will detect that the video has those padding lines or it will report the number of "usefull lines" ? Thanks for the answers and happy 2010 to everyone
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5th January 2010, 16:26 | #12 | Link |
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For your first question, the answer is yes. But I think that any H.264 compilant, non-buggy decoder should be able to do that. Remember, 1080p is not mod16. As for mediainfo I don't know the answer.
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