On Wed, Sep 26, 2012 at 12:08:00PM +0100, Chris Cannam wrote:
> On 11 June 2012 18:47, Robin Gareus wrote:
There is more to fix.
The meterbridge website still claims that those meters 'almost' conform
to some standards while in fact they even don't come close.
According to the standard, a VU measures the average of the absolute
value. For a steady input signal around 1 kHz, it must rise to 99% of
the real value in 300ms and overshoot it by 1 to 1.5% before falling
back to 100%. The one from meterbridge measures RMS and rises to the
final value in around 5.3ms, that is more than 50 times too fast (at
a sample rate of 48 kHz, and worse for higher sample rates).
According to the standards, a PPM or IEC meter must have a controlled
rise time of 5 or 10ms (depending on the standard). The one from
meterbridge indicates peak sample values instead.
A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)
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