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  • ShoreWare 8 Codec Usage?

    Anyone have guidance to offer for determining what codecs to use in ShoreWare 8? This question was originally posted to yahoo power users group but doesn't have a very active membership so I will post here for comments:

    Follow up to my original message below I modified my intra-site codec group (bottom of message) and replace BV32 with L16/8000 and BV16 with G722. BV32 seemed to produce feedback even though, I think, that was something addressed in the codec design. L16/8000 is traditional Shoretel codec we used in earlier releases that has that “amazing call quality,” one of the things that sold us on the system. L16/8000 seems to produce the highest level of fidelity without feedback issues or too much background noise. G722 seems to be almost as good as L16/8000 but better than BV16. G722 could any of the be various wideband codec versions. I don’t know which version of G722, .1, or .2 Shoretel implemented:
    • G722 is a subband-codec that divides 16 kHz band into two subbands, each coded using ADPCM.
    • G722.1 is Coding at 24 and 32 kbit/s for hands-free operation in systems with low frame loss.
    • G722.2 is a wideband coding of speech at around 16 kbit/s using adaptive multi-rate (6.60, 8.85, 12.65, 14.25, 15.85, 18.25, 19.85, 23.05 and 23.85) wideband.

    Since August, I have been very satisfied with my intra and intra site codec groups working great in my WAN environment.

    Tom

    From: Porter, Thomas L
    Sent: Tuesday, August 05, 2008 9:45 PM
    To: '[email protected]'
    Subject: ShoreWare 8 Codec Usage?

    Anyone have guidance to offer for determining what codecs groups to use in ShoreWare 8? A lot has to do with ethernet network configuration and bandwidth but without getting into too much detail what do you think is the best grouping? The problem am looking to address is that when there is a audio quality issue I don’t know which codec the system negotiated relative to the network connectivity issues.

    Also wideband codecs get a lot of IP560 speakerphone mic feedback that some may notice on 7.5 and earlier when using the Linear Broadband (256 Kbps) codec. Rarely an issue with Linear (128 Kbps). On SW8 high bandwidth group I notice occasional feedback but there are multiple codecs that could be the issue.

    Shoretel SW8 has default codec groups shown below (from admin guide) and I am configuring my own to reduce codec vs. network variables.
    Very High Bandwidth Codecs
    1. L16/16000
    2. G722/8000
    3. BV32/16000
    4. L16/8000
    5. PCMU/8000
    6. DVI4/8000
    7. BV16/8000
    8. G729/8000
    High Bandwidth Codecs
    1. G722/8000
    2. BV32/16000
    3. L16/8000
    4. PCMU/8000
    5. DVI4/8000
    6. BV16/8000
    7. G729/8000
    Medium Bandwidth Codecs
    1. G722/8000
    2. BV32/16000
    3. PCMU/8000
    4. DVI4/8000
    5. BV16/8000
    6. G729/8000
    Low Bandwidth Codecs
    1. BV32/16000
    2. DVI4/8000
    3. BV16/8000
    4. G729/8000
    5. PCMU/8000
    Very Low Bandwidth Codecs
    1. G729/8000
    2. PCMU/8000
    Fax Codecs High
    1. L16/8000
    2. PCMU/8000
    Fax Codecs Low
    1. PCMU/8000
    2. L16/8000

    My digested codec group consists of the following:
    Group “Inter-site Codecs”
    • BV16/8000 – high voice quality, mid-bitrate
    • PCMU/8000 - default
    • G729/8000 – very low bandwidth and tolerance for transmission delays.
    Group “Intra-site Codecs”
    • BV32/16000 – high voice quality, wideband codec
    • BV16/8000 – high voice quality, mid-bitrate
    • PCMU/8000 - default

  • #2
    Codec Choice

    Codec choice is like a coke vs pepsi thing.

    We ONLY use pcmu/8000 for ALL voice calls. We have tried several others and users complain nonstop. They may have been able to get used to the difference after a while, but we did not force the issue.

    The default shoretel 8 codec (especially when people are used to the 7 7.5 default) sounds like you are in a tunnel, speaking into a tin can, while sky diving.

    Mileage may vary

    Comment


    • #3
      I have just upgraded to 8 and have run into this codec conundrum. For now I have made a new Codec List with just PCMU/8000 as we started on 7.5 and our users were used to that sound.

      I have QoS configured, everyone has a 100Mbps connection with 1Gbps between all switches. Our other site is connected with a point to point fiber running at 1Gbps with under 2ms latency. We have 80 phones between the two sites each site has a SG-120 and our HQ has a SG-T1. All calls go out the HQ site PRI.

      Any advice in the codec realm?

      Comment


      • #4
        Codec

        If the users are happy with PCMU/8000 why change?

        Comment


        • #5
          No reason, didn't know if there was a preferred setup or a higher quality codec we could use. I am curious though how it decides which codec to use when it has a list to chose from.

          Comment


          • #6
            We've defaulted to a custom codec list for intra-site that encompasses the following:

            L16/8000
            G722/8000
            PCMU/8000

            Works great for us and customers don't seem to complain about any akwardness in the sound.

            Comment


            • #7
              We have 12 sites connected an MPLS WAN with BGP. We use a 25_74_1 QOS profile and scale office WAN links accordingly. All VOIP rides the 25% EF46 queue.

              That said, our testing yielded that BV32 and the higher fidelity codecs sounded so different than the G729-ish codecs, that our business unit interpreted it as lower quality.

              We ended up with Tom Porter's digested lists. I guess great minds think alike, right?

              Regards,
              Jonathan D. Pollard

              Comment

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