x265很强，永远的0只有1G多，可效果完全不输8G，有图有真相

好久没关注视频编码技术了，真是日新月异

How can HEVC encode video files twice as efficiently as previous video coding standards?

• Most of the power of video compression standards comes from a technique known as motion compensated prediction.  Blocks of pixels are encoded by making reference to another area in the same frame (intra-prediction), or in another frame (inter-prediction).  Where H.264/AVC defines macroblocks up to 16×16 pixels, HEVC can describe a much larger range of block sizes, up to 64 x 64 pixels.
• HEVC allows predicted blocks to be coded in different block sizes than the residual error.  Each top level coding unit (or CTU) is first coded as a prediction quad-tree, where at each depth the encoder decides whether to encode with merge/skip, inter, or intra coding. The residual from those predictions is then coded with a second quad-tree which can optionally have greater depth than the prediction quad-tree.  For instance, this allows the residual error from a 32×32 inter coded coding unit (CU) to be represented by a mixture of 16×16, 8×8, and 4×4 transforms.
• HEVC can encode motion vectors with much greater precision, giving a better predicted block with less residual error.  There are 35 intra-picture directions, compared with only 9 for H.264/AVC.
• HEVC includes Adaptive Motion Vector Prediction, a new method to improve inter-prediction.
• An improved deblocking filter
• Sample Adaptive Offset – an additional filter that reduces artifacts at block edges

H.265/HEVC的编码架构大致上和H.264/AVC的架构相似，主要也包含，帧内预测
(intra prediction)、帧间预测(inter prediction)、转换 
(transform)、量化(quantization)、去区块滤波器(deblocking filter)、熵编码(entropy 
coding)等模块，但在HEVC编码架构中，整体被分为了三个基本单位，分别是：编码单位(coding unit,CU)、预测单位(predict unit,PU) 和转换单位(transform unit,TU )。

　　比起H.264/AVC，H.265/HEVC提供了更多不同的工具来降低码率，以编码单位来说，H.264中每个宏块(macroblock/MB)大小都是固定的16x16像素，而H.265的编码单位可以选择从最小的8x8到最大的64x64。

　　同时，H.265的帧内预测模式支持33种方向(H.264只支持8种)，并且提供了更好的运动补偿处理和矢量预测方法。

　　反复的质量比较测试已经表明，在相同的图象质量下，相比于H.264，通过H.265编码的视频大小将减少大约39-44%。由于质量控制的测定方法不同，这个数据也会有相应的变化。
　　

　　通过主观视觉测试得出的数据显示，在码率减少51-74%的情况下，H.265编码视频的质量还能与H.264编码视频近似甚至更好，其本质上说是比预期的信噪比(PSNR)要好。

看过一个宣传265和264区别的宣传画
区别是 264  把一个画面平均分成许多小方块
265则是有大有小 不平均的小方块  算法比264复杂许多
 





 

x265很强，永远的0只有1G多，可效果完全不输8G，有图有真相

虽然音频只有2.0声道，但这个压缩率和画质已经很牛了

估计X265普及后又会有一轮洗盘潮了