Goals
VC1 is designed to offer very
high image quality with
excellent compression efficiency
H.264/MPEG-4 AVC is designed to meet a variety of industry needs with many profiles and levels, allowing for
varying compression, quality and CPU usage levels, where the lowest level is for portable devices, designed with low CPU usage in mind, while the high levels are designed with very high quality and compression efficiency in mind.
Profiles
VC-1 profiles
|
Simple |
Main |
Advanced |
Baseline intra frame compression |
Yes |
Yes |
Yes |
Variable-sized transform |
Yes |
Yes |
Yes |
16-bit transform |
Yes |
Yes |
Yes |
Overlapped transform |
Yes |
Yes |
Yes |
4 motion vector per macroblock |
Yes |
Yes |
Yes |
¼ pixel luminance motion compensation |
Yes |
Yes |
Yes |
¼ pixel chrominance motion compensation |
No |
Yes |
Yes |
Start codes |
No |
Yes |
Yes |
Extended motion vectors |
No |
Yes |
Yes |
Loop filter |
No |
Yes |
Yes |
Dynamic resolution change |
No |
Yes |
Yes |
Adaptive macroblock quantisation |
No |
Yes |
Yes |
B frames |
No |
Yes |
Yes |
Intensity compensation |
No |
Yes |
Yes |
Range adjustment |
No |
Yes |
Yes |
Field and frame coding modes |
No |
No |
Yes |
GOP Layer |
No |
No |
Yes |
Display metadata |
No |
No |
Yes |
|
Simple |
Main |
Advanced |
H.264 Predefined profiles
Feature |
CBP |
BP |
XP |
MP |
HiP |
Hi10P |
Hi422P |
Hi444PP |
I and P slices |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
B slices |
No |
No |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
SI and SP slices |
No |
No |
Yes |
No |
No |
No |
No |
No |
Flexible macroblock ordering (FMO) |
No |
Yes |
Yes |
No |
No |
No |
No |
No |
Arbitrary slice ordering (ASO) |
No |
Yes |
Yes |
No |
No |
No |
No |
No |
Redundant slices (RS) |
No |
Yes |
Yes |
No |
No |
No |
No |
No |
Data partitioning |
No |
No |
Yes |
No |
No |
No |
No |
No |
Interlaced coding (PicAFF, MBAFF) |
No |
No |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
Multiple reference frames |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
In-loop deblocking filter |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
CAVLC entropy coding |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
Yes |
CABAC entropy coding |
No |
No |
No |
Yes |
Yes |
Yes |
Yes |
Yes |
8×8 vs. 4×4 transform adaptivity |
No |
No |
No |
No |
Yes |
Yes |
Yes |
Yes |
Quantization scaling matrices |
No |
No |
No |
No |
Yes |
Yes |
Yes |
Yes |
Separate Cb and Cr QP control |
No |
No |
No |
No |
Yes |
Yes |
Yes |
Yes |
Monochrome (4:0:0) |
No |
No |
No |
No |
Yes |
Yes |
Yes |
Yes |
Chroma formats (4:2:x) |
0 |
0 |
0 |
0 |
0 |
0 |
0, 2 |
0, 2, 4 |
Largest sample depth |
8 |
8 |
8 |
8 |
8 |
10 |
10 |
14 |
Separate color plane coding |
No |
No |
No |
No |
No |
No |
No |
Yes |
Predictive lossless coding |
No |
No |
No |
No |
No |
No |
No |
Yes |
总的来说,从压缩比上来看,H.264的压缩比率更高一些,也就是同样的视频,通过H.264编码算法压出来的视频容量要比VC-1的更小,但是VC-1 格式的视频在解码计算方面则更小一些,一般通过高性能的CPU就可以很流畅的观看高清视频。
VC-1和H.264 都可以支持全高清视频1080p。
1080代表垂直方向的扫描线的数量,p表示progressive scan,而不是interlaced scan,1080p也被称为
full HD or
full high definition although 1080i is also "Full HD"
所谓标清,是物理分辨率在720p以下的一种视频格式。720p是指视频的垂直分辨率为720线逐行扫描。具体的说,是指分辨率在400线左右的VCD、DVD、电视节目等“标清”视频格式,即标准清晰度。而物理分辨率达到720p以上则称作为高清,(英文表述High Definition)简称HD。关于高清的标准,国际上公认的有两条:
视频垂直分辨率超过720p或1080i;视频宽纵比为16:9。
对于“高清”和“标清”的划分首先来自于所能看到的视频效果。由于图像质量和信道传输所占的带宽不同,使得数字电视信号分为HDTV(高清晰度电视)、SDTV(标准清晰度电视)和LDTV(普通清晰度电视)。从视觉效果来看HDTV的规格最高,其图像质量可达到或接近35mm宽银幕电影的水平,它要求视频内容和显示设备水平分辨率达到1000线以上,分辨率最高可达1920×1080。从画质来看,由于高清的分辨率基本上相当于传统模拟电视的4倍,画面清晰度、色彩还原度都要远胜过传统电视。而16:9的宽屏显示也带来更宽广的视觉享受。从音频效果看,高清电视节目将支持杜比5.1声道环绕声,而高清影片节目将支持杜比5.1 True HD规格,这将给我们带来超震撼的听觉享受。
HD FULL 全高清
所谓全高清(FULL HD),是指物理分辨率高达1920×1080显示(包括1080i和1080P),其中i(interlace)是指隔行扫描;P(Progressive)代表逐行扫描,这两者在画面的精细度上有着很大的差别,1080P的画质要胜过1080i。对应地把720称为标准高清。很显然,由于在传输的过程中数据信息更加丰富,所以1080在分辨率上更有优势,尤其在大屏幕电视方面,1080能确保更清晰的画质。