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[思考][聊天]x264 设置求教 macroblock options

楼层直达
级别: 新手上路
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2008-04-24
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macroblock options
下面有 I4X4 I8X8 P8X8 I8X8 这类选项

他们实际作用 看介绍好像是 动态块划分方法?

我在压片中测试 开启全部和关闭全部 好像没看出什么差距啊

这几个选项具体是什么作用?请压片高手指教 它们主要是对什么类型的影片作用最大,最明显
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只看该作者 1楼 发表于: 2008-08-04
Macroblock
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Macroblock is a term used in video compression, which represents a block of 16 by 16 pixels. Each macroblock contains 4 Y block, 1 Cb block, 1 Cr block (4:2:0). (It also could be represented by 4:2:2 or 4:4:4 YCbCr format). Macroblocks can be subdivided further into smaller blocks, called partitions. H.264, for example, supports block sizes as small as 4x4.

[edit] Macroblock coding

+------+------+-------+--------+-----+----+----+--------+
| ADDR | TYPE | QUANT | VECTOR | CBP | b0 | b1 | ... B5 |
+------+------+-------+--------+-----+----+----+--------+

* ADDR .... address of block in image
* TYPE .... identifies type of macroblock (intra-frame, inter frame, bi-directional inter frame)
* QUANT ... quantization value to vary quantization
* VECTOR... motion vector
* CBP...... Coded Block Pattern, some blocks in macroblock match well, some match poorly - this is bit mask indicating which one is present.
* the blocks (4 Y, 1 Cr, 1 Cb)

[edit] Macroblocking

This is a non-technical term used when macroblocks are missing and show up as video errors. Square areas of the picture do not show the correct portion of the image, but instead show a single color block. Advanced decoders hide these types of errors with a technique called error concealment. This effect is also referred to as microblocking.

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