H265计算Level的方法
比如分辨率: 1920*1080, 参考帧率: 60的h265码流是哪个level呢?
H.265的亮度(luma)图像的大小计算公式为:
samples = width * height
1920*1080计算得:2073600
每秒亮度采样数量为每帧samples乘以帧率.
samples/s =samples*参考帧率
2073600*60 计算得:124416000
参考Rec. ITU-T H.265 v5 (02/2018) 267页查表
| Level | Max luma sample rate (samples/s) | Max luma picture size (samples) | Max bit rate for Main and Main 10 profiles (kbit/s)[A] | Example picture resolution @ highest frame rate[B] (MaxDpbSize[C]) More/Fewer examples | |
|---|---|---|---|---|---|
| Main tier | High tier | ||||
| 1 | 552,960 | 36,864 | 128 | – | 128×96@33.7 (6) 176×144@15.0 (6) |
| 2 | 3,686,400 | 122,880 | 1,500 | – | 176×144@100.0 (16) 352×288@30.0 (6) |
| 2.1 | 7,372,800 | 245,760 | 3,000 | – | 352×288@60.0 (12) 640×360@30.0 (6) |
| 3 | 16,588,800 | 552,960 | 6,000 | – | 640×360@67.5 (12) |
| 3.1 | 33,177,600 | 983,040 | 10,000 | – | 720×576@75.0 (12) |
| 4 | 66,846,720 | 2,228,224 | 12,000 | 30,000 | 1,280×720@68.0 (12) |
| 4.1 | 133,693,440 | 20,000 | 50,000 | 1,280×720@136.0 (12) | |
| 5 | 267,386,880 | 8,912,896 | 25,000 | 100,000 | 1,920×1,080@128.0 (16) |
| 5.1 | 534,773,760 | 40,000 | 160,000 | 1,920×1,080@256.0 (16) | |
| 5.2 | 1,069,547,520 | 60,000 | 240,000 | 1,920×1,080@300.0 (16) | |
| 6 | 1,069,547,520 | 35,651,584 | 60,000 | 240,000 | 3,840×2,160@128.0 (16) |
| 6.1 | 2,139,095,040 | 120,000 | 480,000 | 3,840×2,160@256.0 (16) | |
| 6.2 | 4,278,190,080 | 240,000 | 800,000 | 3,840×2,160@300.0 (16) | |
查表可知
Level 3.1
samples 983040
Level 4 和 Level 4.1
samples 2228224
根据samples可知,Level为Level 4或Level 4.1; Level的确定原则是找<=的关系.
Level 4
samples/s 66846720
Level 4.1
samples/s 133693440
根据samples/s可知,Level为Level 4.1; Level的确定原则是找<=的关系.
补充说明: RTP传输h265的RFC协议是7798协议, RTP Payload Format for High Efficiency Video Coding (HEVC)
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