欢迎访问 水平网    今天是:2018年06月22日 注册 | 登录 | 订阅 | 收藏
>> 网络技术 >> VOIP技术 >> VoIP常见编码的带宽计算
推荐文章
热点文章
专题
JQuery框架
Prototype.js
HTML5

VoIP常见编码的带宽计算

作者:未知,  来源:网络,  阅读:793,  发布时间:2014-07-15 【放入收藏夹

voip带宽计算VOIP计算方法与所选用的编码方法有关,而与哪个厂家的没有什么关系,公式如下:

带宽=包长度×每秒包数
=包长度×(1/打包周期)
=(Ethernet头+IP头+UDP头+RTP头+有效载荷)×(1/打包周期)
=(208bit +160bit+64bit+96bit +有效载荷)×(1/打包周期)
=(528bit+(打包周期(秒)×每秒的比特数))×(1/打包周期)
=( 528 / 打包周期 ) + 每秒比特数
 

根据各种编码方式,得出:

G711:20ms打包,带宽为 ( 528/20 + 64) Kbit/s=90.4 Kbit/s
G729:20ms打包,带宽为 ( 528/20 + 8 ) Kbit/s= 34.4 Kbit/s
G723:5.3k,30ms打包,带宽为 ( 528/30 + 5.3 ) Kbit/s=22.9 Kbit/s
业界一般按照下表提供的IP网带宽系数和以太网带宽系数来设计网络带宽:
编解码技术 压缩速率(Kbps) 打包周期(ms) IP网带宽系数 以太网带宽系数
G.711 a/u 64 20 1.25 1.41
G.729 a/b 8 20 0.38 0.54
G.723.1(5.3kbit/s) 5.3 30 0.27 0.37
G.723.1(6.3Kbit/s) 6.3 30 0.25 0.36
H.263(384Kbit/s) ≈384 10 6 6.2
备注:采用某种编码方式时,用64K乘以相应的带宽系数就可以得出其实际占用的带宽。当然如果是中继接口,还需要考虑信令占据一定的带宽,一般按照2.5%来计算。

举例:

PBX--E1--Router---IP----Router---E1---PBX

这里的带宽占用分为2个部分,1是与PBX连接的POTS部分,1是路由器之间的VOIP部分。一般来说,每路模拟线路的带宽占用是64Kbps,而IP语音的占用会因不同的编码标准有所不同,从8K到80K可供选择。QoS的保证有个要求,就是延迟<=150ms,抖动<=30ms,丢包率<=1%

 

SPEEX 带宽

We have finally almost finished Speex coding on AR1688 DSP. This open source voice codec turned out to be much more complicated than we expected. There are 8 different bitrate with 8k sampling from 2.15kpbs to 24.6kpbs. I am writing this article to answer a question of how much bandwidth this codec actually use during a call.

Let us calculate based on 802.3 ethernet using SIP protocol:

Ethernet CRC: 4 bytes
MAC header: 14 bytes
IP header: 20 bytes
UDP header: 8 bytes
RTP header: 12 bytes


Speex data: x bytes x depends on bitrate used and number of frames packed in an ethernet packet ("Voice frames per TX" option in AR1688)

Total: (58 + x) bytes

Speex uses 20ms as a frame the size of compressed data in a frame with different bitrate are:

2.15kbps: 6 bytes
3.95kbps: 10 bytes
5.95kbps: 15 bytes
8kbps: 20 bytes
11kbps: 28 bytes
15kbps: 38 bytes
18.2kbps: 46 bytes
24.6kbps: 62 bytes

When only 1 frame is included in an ethernet frame the actually used bandwidth are: 同花顺至尊版

2.15k: 25.6k
3.95k: 27.2k
5.95k: 29.2k
8k: 31.2k
11k: 34.4k
15k: 38.4k
18.2k: 41.6k
24.6k: 48k

When 2 frames are included in an ethernet frame the actually used bandwidth are:

2.15k: 14k
3.95k: 15.6k
5.95k: 17.6k
8k: 19.6k
11k: 22.8k
15k: 26.8k
18.2k: 30k
24.6k: 36.4k

When 3 frames are included in an ethernet frame the actually used bandwidth are:

2.15k: 10.1k
3.95k: 11.7k
5.95k: 13.7k
8k: 15.7k
11k: 18.9k
15k: 22.9k
18.2k: 26.1k
24.6k: 32.5k

When 4 frames are included in an ethernet frame the actually used bandwidth are:

2.15k: 8.2k
3.95k: 9.8k
5.95k: 11.8k
8k: 13.8k
11k: 17k
15k: 21k
18.2k: 24.2k
24.6k: 30.6k

TGAS:VoIP编码带宽
评论【共有0条评论】查看所有评论
称呼:(*)   邮箱:   QQ:   验证码: 看不清楚?点击刷新验证码