G.711 is an audio coding method developed by the International Telecommunication Union (ITU-T)

http://zh.wikipedia.org/zh-cn/G.711

• ITU-T G.711 page
• ITU-T g.191 software tools for speech and audio coding, including g.711 C code
• Code Project C # Implementation of g.711 with source code

G.711 is an audio coding method developed by the International Telecommunication Union (ITU-T), also known as the ITU-T G.711.

Basic information Editing

It is a set of speech compression standards set out by ITU-T, which represents a sampling standard for logarithmic PCM (logarithmic pulse-code modulation), mainly used in telephones. It mainly uses the Pulse code modulation to the audio sampling, the sampling rate is 8k per second. It uses a 64Kbps uncompressed channel to transmit voice signals. The compression rate is 1:2, which is to compress 16 bits of data into 8 bits. G.711 is the mainstream waveform sound codec. There are two main compression algorithms under the G.711 standard. One is µ-law Algorithm(also known as often u-law, Ulaw, Mu-law), mainly used in North America and Japan, and the other is A-law Algorithm, mainly used in Europe and other parts of the world. Among them, the latter is specially designed to facilitate computer processing.2 Other instructions for editing G711 G723 G729 line account for how much bandwidth problemBandwidth = packet Length x packets per second = packet length x (1/pack cycle) = (Ethernet head +ip Head +udp Head +RTP Head + payload) x (1/pack cycle) = (208bit +160bit+64bit+96bit + payload) x (1/pack cycle) = (528bit+ (Pack cycle (seconds) x bits per second) x (1/pack cycle) = (528/pack cycle) + bits per second in accordance with the above calculation formula:G711:20MS Packaging, bandwidth for (528/20 +) kbit/s=90.4 kbit/sg729:20ms Packaging, bandwidth for (528/20 + 8) kbit/s= 34.4 kbit/sg723:5.3k,30ms Packaging, bandwidth for ( 528/30 + 5.3) kbit/s=22.9 kbit/s the industry generally designs network bandwidth according to the IP network bandwidth coefficients and Ethernet bandwidth coefficients provided in the following table: Codec technology compression rate (Kbps) packaging period (MS) IP network bandwidth factor Ethernet bandwidth factor g.711 a/u 64 2 0 1.25 1.41g.729 A/b 8 0.38 0.54g.723.1 (5.3kbit/s) 5.3-0.27 0.37g.723.1 (6.3kbit/s) 6.3-0.25 0.36h.263 (384KBIT/S) ≈384 10 6 6.2 Note:When using a certain encoding method, it is possible to derive its actual occupied bandwidth by multiplying the corresponding bandwidth factor by 64K. Of course, if it is a relay interface, you also need to consider the signaling to occupy a certain bandwidth, generally in accordance with 2.5% to calculate. If you do not understand the above calculation method, just remember the following results: G711 actual consumption of bandwidth per line 90.4KBIT/S 100 lines concurrently occupied 9mbpsg729 actual consumption of bandwidth per line 34.4KBIT/S 100 lines concurrently occupied 3.4mbpsg723 actual consumption of bandwidth 22.9KBIT/S 100 lines per line concurrently occupying 2.2Mbps

G.711 is an audio coding method developed by the International Telecommunication Union (ITU-T)