Level meter dB info

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    Alex corrected the level meters yesterday.
    They are scaled in decibels now (as any audio level meter is).

    I measured the ranges for the start of green, yellow and red level at the new logarithmically scaled level meters.
    I give the ranges in a range of 0 dB for maximum level before distortion up to -infinite for silence.

    up to -40 dB: No display of any bar (white)
    above -40 dB: Start of green level (better visible above -39 dB)
    about -30 dB: Quarter of the level meter length in green
    about -22 dB: Half of the level meter length in green
    about -13 db: Three quarters of the level meter in green
    about -9 dB: Maximum length in green (exactly at 8.73 dB)
    -8.7 to -5.6 dB: Yellow bar
    above -5.6 dB: Red bar, but not necessarily distortion (exactly from -5.58 dB and above)

    Please note that these are negative values, so above means a lower absolute value (numerical value without the minus sign).

    The level meter only displays the incoming maximum (from any number of channels) in front of the volume sliders.
    It is also the level that get send out to the other participants or the server.

    For peer to peer use, the level should be mostly green and can get sometimes in the yellow range and very seldom and only very sporadicly without a loud impact into the red. Receivers may need to reduce the volume in their reception volume sliders to avoid overflow distortion of the added signals.

    For the simple server (mix server) the participants may need to reduce the input level at the interface or sound panel, because the signals add up in the server which can lead to overflow distortion in the sum signals sended back.

    I’m not sure if Alex does reduce the sound level in the simple server (mix server) depending on the number of participants, but since there is no individual volume control at the simple server, the participants need to level their signal in a way that it mixes well. For a choir or equal instruments that would be an equal level for all, for a mixed ensemble the member need to tell the others how to change their levels.


    Reducing artifacts caused by the level meters (mostly on slower machines or with many connections):

    The active level meters (at least currently) can put a big load on the machine.
    Users of slower ones might therefor want to disable the level meter display.
    This could be accomplished by removing the hook (or click on the little “on” that does not change) on the right side (or below) the users level meter in the left column.

    A good use would be to level in after entering the stage (works well with the local volume in the left column), half to three quarter of the level meter for peaks is a good range if you level in as loud as you can imagine it can get. If you have done that, disable the level meter on slow machines (or maybe also with many connections). Then make your connections to others (who hopefully have done that too).

    If you are not sure keep an eye on the CPU load. There are programs in every supported operating system that can display the CPU load and idle in percent.
    Alex recommends not more that 10% of CPU usage, which would result in 90% idle. (I’m not sure if Alex means 10% including all processes or only for Soundjack and Browser.)
    A MBP from 2008 might use about 20% for the operationg system alone, but still runs well with 66% idle (34% total load) and acceptable with 50% idle (50% total load).

    The level meters are always switched on after a new loading of the stage, so don’t forget to disable them if you need to reload the stage.

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