Voip Think- Voice over IP - Asterisk and SER - SIP IAX and H323

3CX VoIP Phone System, IP PBX for Windows
3CX PBX and Phone System for Windows
Download free edition

SEARCH

  • VoIP Protocols
  •    

  • Telephones
  •    

  • QoS (Quality of Service)
  •    

  • Codecs
  •    

  • Asterisk
  •    

  • 3CX PBX
  •    

  • SER (Sip Express Router)
  •    

  • More information
  •    

     

      Codecs  

     
        Summary table   G.711 codec process   Audio samples   New codecs G.711.1 -G722.2--G729.1      
     

     
    G711.1 - G729.1 - G722.1 - G722.1

    in last years it is appearing new codec versions of G711, G729 or G722 classic codecs

    G 711.1

    The new G.711.1 codec has been approved by ITU-T on March 2008.

    The new G.711.1 codec is an embedded wideband codec built on top of the narrowband G.711 codec. Its aim is
    to easily interoperate with the legacy G.711 infrastructure. It provides two extension layers. The first extension
    improves the quality of G.711 in the low frequencies, including the 50-300 Hz band, which is usually not
    transmitted with G.711. The second extension encodes high frequencies up to 7 kHz using distinct extension
    layers.

    The birate of G.711.1 requires 80 or 96 Kbps depending of the use of one or two extension layer.


    The G.711.1 codec has a low delay of only 5 ms

    This codec aims to achieve high-quality speech services over broadband networks, particularly for IP phone and multi-point speech conferencing

    G.729.1

    The G.729.1 codec is also an embedded wideband codec, built on top of a G.729 narrowband version. G.729.1
    is also "scalable" in that there are many extension layers that are added on top of each other. The first extension
    layer provides enhanced narrowband quality at 12 Kbps. From there on, extra layers of 2 Kbps each add
    wideband capability with increasing quality, up to a maximum rate of 32 Kbps. At that rate, G.729.1 is said to
    provide acceptable music quality. As is the case for G.711.1, the embedded and scalable nature of G.729.1
    comes at a cost in quality versus the bit rate needed, and G.729.1 does not perform as well as other wideband
    codecs, such as G.722.2 (AMR-WB) at equal rate

    The main uses of this codec are: VoIP (IP telephony) including IP phones, other VoIP handsets, softphones, IP PBXs; media servers/gateways; call center equipment; voice recording equipment; test equipment; audio/video conferencing for enterprise corporate networks or for the mass market (like PSTN emulation over xDSL or wireless access); voice messaging servers.

    It is also known as G729J or G729EV.

    G.722.1 or SIREN 7

    G.722.1 or SIREN 7 describes a digital wideband coder algorithm that provides an audio bandwidth of 50 Hz to 7 kHz, operating at a bit rate of 24 kbps or 32 kbps. G.722.1 is useful for hands-free operation in HD VoIP systems with low frame loss.

    It exists also the G.722.1 Annex C or SIREN 14 that provides an audio badwith up to 14 Khz operating at a bir rate of 24, 32, y 48 kbit/s.


    G.722.2 o AMR-WB ("Adaptive Multirate Wideband")

    The Adaptive Multi-Rate Wideband Codec (AMR-WB) is a speech coder standard introduced by the 3rd Generation Partnership Project (3GPP), The AMR-WB Codec has been approved by the ITU-T standards body and is referred to as G.722.2.This speech coder is mainly used for speech compression in the 3rd generation mobile telephony.

    This codec has nine basic bit rates, 23.85, 23.05, 19.85, 18.25, 15.85, 14.25, 12.65, 8.85 and 6.6 kbit/s. This codec works on the principle of Algebraic Code Excited Linear Prediction (ACELP) for all bit rates. To reduce average bit rate, this codec supports the discontinuous transmission (DTX), using Voice Activity Detection (VAD) and Comfort Noise Generation (CNG) algorithms.

    The coder works with a framesize of 20 msec and the algorithmic delay for the coder is 25 msec.

     

     
     
     
    Spanish   |   About us    |   Contact   |   Collaborate  |   Advertising