[ih] Evolution of Internet audio and video

[Craig Partridge]

On Mon, Sep 29, 2025 at 3:59 PM Karl Auerbach <karl at iwl.com> wrote:

>
> All in all the cure for many things was to add delay before rendering
> content.  But that affected conversational uses where, according to the ITU
> we have a round trip budget of only about 140 milliseconds before people go
> into half-duplex/walkie-talkie mode.  I really wanted to get my physicist
> friends to consider increasing the speed of light, but they were resistant
> to the idea.
>
Fun story -- I had reason to go through the literature that led to the
140ms standard.  Turns out to have been lousy test equipment (I don't
recall anymore and my published versions of this discovery sanitized the
stupidity, but I think they turned out to be testing the quality of the
echo cancellers).  Riesz and Klemmer did the good quality tests in the
mid-1960s (Bell System Technical Journal) and they determined 600ms
round-trip was just fine.

Craig

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