[Tech1] BBC News at Ten new look

[Chris Woolf]

On 17/06/2022 14:17, Pat Heigham via Tech1 wrote:
>
> Poor audio on Zoom?
>
> Where's the bloody mic?
>
> On the computer - miles away from mouth!
>

.. But not only that. The audio is having to deal with using a highly 
un-optimised "telephone hybrid" arrangement to separate the two-way 
sound. And while the video can be cleverly compressed on a multi-frame 
basis, the audio can't - it needs entirely different data compression. 
The video compression can also take advantage of variable data rate 
compression so that time can stretch backwards and forwards during a 
transmission. Doing that with sound causes all sorts of grief.

And when it comes to analogue phone land-lines ... these are digitised 
at the exchange and if you have low level audio (high line loss, quiet 
speaker, etc) then only about 4bits of the ADC get used. Couple that 
with no dithering - I've no idea why it is not there - and the granular 
distortion can be horrendous. Add on the fact that most people are using 
DECT phones which concatenate their (not necessarily very good) codecs 
and even if the acoustic source is good, what comes out at the other end 
can be appalling.


Chris Woolf