多媒体|AVC编码中的规格 （High、Baseline、Main什么意思（还有High@L3.0、High@L4.0、High@L5.1等））
咳咳，在这里首先要阐明所谓的AVC其实就是H.264标准，是由ITU-T和ISO/IEC组成的联合视频组（JVT，Joint Video Team）一起开发的，ITU-T给这个标准命名为H.264（以前叫做H.26L），而ISO/IEC称它为MPEG-4 高级视频编码（Advanced Video Coding，AVC），它定位于覆盖整个视频应用领域，包括：低码率的无线应用、标准清晰度和高清晰度的电视广播应用、Internet上的视频流应用，传输高清晰度的DVD视频以及应用于数码相机的高质量视频应用等等。
AVC的规格分为三等，从低到高分别为：Baseline、Main、High。
Baseline（最低Profile）级别支持I/P 帧，只支持无交错（Progressive）和CAVLC，一般用于低阶或需要额外容错的应用，比如视频通话、手机视频等；
Main（主要Profile）级别提供I/P/B 帧，支持无交错（Progressive）和交错（Interlaced），同样提供对于CAVLC 和CABAC 的支持，用于主流消费类电子产品规格如低解码（相对而言）的mp4、便携的视频播放器、PSP和Ipod等；
High（高端Profile，也叫FRExt）级别在Main的基础上增加了8x8 内部预测、自定义量化、无损视频编码和更多的YUV 格式（如4：4：4）用于广播及视频碟片存储（蓝光影片），高清电视的应用。
AVC 的规格主要是针对兼容性的，不同的规格能在相同级别上的平台应用。
至于Baseline@L x.x、Main@L x.x、High@L x.x形式则是在不同级别下的码流级别，数值越大码流就越大，更耗费资源。所以就码流而言High@L3.0
Levels
As the term is used in the standard, a "level" is a specified set of constraints indicating a degree of required decoder performance for a profile. For example, a level of support within a profile will specify the maximum picture resolution, frame rate, and bit rate that a decoder may be capable of using. A decoder that conforms to a given level is required to be capable of decoding all bitstreams that are encoded for that level and for all lower levels.
| Level | Max decoding speed | Max frame size | Max video bit rate for video coding layer (VCL) kbit/s |
Examples for high resolution @ highest frame rate (max stored frames) |
|||
|---|---|---|---|---|---|---|---|
| Luma samples/s | Macroblocks/s | Luma samples | Macroblocks | Baseline, Extended and Main Profiles |
High Profile | ||
| 1 | 380,160 | 1,485 | 25,344 | 99 | 64 | 80 | 128×96@30.9 (8) 176×144@15.0 (4) |
| 1b | 380,160 | 1,485 | 25,344 | 99 | 128 | 160 | 128×96@30.9 (8) 176×144@15.0 (4) |
| 1.1 | 768,000 | 3,000 | 101,376 | 396 | 192 | 240 | 176×144@30.3 (9) 320×240@10.0 (3) 352×288@7.5 (2) |
| 1.2 | 1,536,000 | 6,000 | 101,376 | 396 | 384 | 480 | 320×240@20.0 (7) 352×288@15.2 (6) |
| 1.3 | 3,041,280 | 11,880 | 101,376 | 396 | 768 | 960 | 320×240@36.0 (7) 352×288@30.0 (6) |
| 2 | 3,041,280 | 11,880 | 101,376 | 396 | 2,000 | 2,500 | 320×240@36.0 (7) 352×288@30.0 (6) |
| 2.1 | 5,068,800 | 19,800 | 202,752 | 792 | 4,000 | 5,000 | 352×480@30.0 (7) 352×576@25.0 (6) |
| 2.2 | 5,184,000 | 20,250 | 404,720 | 1,620 | 4,000 | 5,000 | 352×480@30.7(10) 352×576@25.6 (7) 720×480@15.0 (6) 720×576@12.5 (5) |
| 3 | 10,368,000 | 40,500 | 404,720 | 1,620 | 10,000 | 12,500 | 352×480@61.4 (12) 352×576@51.1 (10) 720×480@30.0 (6) 720×576@25.0 (5) |
| 3.1 | 27,648,000 | 108,000 | 921,600 | 3,600 | 14,000 | 17,500 | 720×480@80.0 (13) 720×576@66.7 (11) 1280×720@30.0 (5) |
| 3.2 | 55,296,000 | 216,000 | 1,310,720 | 5,120 | 20,000 | 25,000 | 1,280×720@60.0 (5) 1,280×1,024@42.2 (4) |
| 4 | 62,914,560 | 245,760 | 2,097,152 | 8,192 | 20,000 | 25,000 | 1,280×720@68.3 (9) 1,920×1,080@30.1 (4) 2,048×1,024@30.0 (4) |
| 4.1 | 62,914,560 | 245,760 | 2,097,152 | 8,192 | 50,000 | 62,500 | 1,280×720@68.3 (9) 1,920×1,080@30.1 (4) 2,048×1,024@30.0 (4) |
| 4.2 | 133,693,440 | 522,240 | 2,228,224 | 8,704 | 50,000 | 62,500 | 1,280×720@145.1 (9) 1,920×1,080@64.0 (4) 2,048×1,080@60.0 (4) |
| 5 | 150,994,944 | 589,824 | 5,652,480 | 22,080 | 135,000 | 168,750 | 1,920×1,080@72.3 (13) 2,048×1,024@72.0 (13) 2,048×1,080@67.8 (12) 2,560×1,920@30.7 (5) 3,672×1,536@26.7 (5) |
| 5.1 | 251,658,240 | 983,040 | 9,437,184 | 36,864 | 240,000 | 300,000 | 1,920×1,080@120.5 (16) 2,560×1,920@51.2 (9) 4,096×2,048@30.0 (5) 4,096×2,160@28.5 (5) 4,096×2,304@26.7 (5) |
| 5.2 | 530,841,600 | 2,073,600 | 9,437,184 | 36,864 | 240,000 | 300,000 | 1,920×1,080@172.0 (16) 2,560×1,920@108.0 (9) 4,096×2,048@63.3 (5) 4,096×2,160@60.0 (5) 4,096×2,304@56.3 (5) |
【多媒体|AVC编码中的规格 （High、Baseline、Main什么意思（还有High@L3.0、High@L4.0、High@L5.1等））】The number of luma samples is 16x16=256 times the number of macroblocks (and the number of luma samples per second is 256 times the number of macroblocks per second).
详情请参考wiki： http://en.wikipedia.org/wiki/H264
