Re: Just out of interest..

Roderick Stewart wrote:
In article <4lilg.46813$uP.1215@xxxxxxxxxxxxxxxxxxxx>, R K Pelligo
wrote:
What is the equivalent "bit rate" for a good quality audio CD?

16 bits per sample x 44,100 samples per second x 2 stereo channels =
1.41 Mbps. There's no bit rate compression at all, so that rate is
constant for all CDs regardless of content.

If you think that's wasteful, you're thinking like an accountant
instead of a broadcast sound engineer, or anybody who cares about
sound quality, so stop it at once.


Linear PCM is wasteful, and audio compression is necessary and useful.

The bit rate of a CD is 1411 kbps. If you used 160 kbps AAC the audio
quality would be very close to CD-quality and nobody would be complaining
about it, but you've allowed 9-times as many radio stations to transmit as
there could have been if linear PCM were used.

DAB multiplexes in the UK only have a capacity of 1184 kbps, which isn't
enough to fit one station in at 1411 kbps. There is a higher capacity mode
that would allow 1411 kbps to be carried, but you would only be able to
receive 1 station per multiplex. I can receive 4 multiplexes, so I would be
able to receive 4 stations. That's not enough, and compression is needed.

It's even more extreme when you look at the case of digital TV. Uncompressed
TV is about 270 Mbps, so if no compression were used we'd only be able to
receive, say 3 TV channels *after* analogue has been switched off.

Audio and video compression is what makes digital TV and digital radio
feasible. It just so happens that the audio compression is being abused by
the broadcasters on DAB, but that's not a reason to say it shouldn't be used
at all.


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

Find the cheapest Freeview & DAB prices:
http://www.digitalradiotech.co.uk/freeview/freeview_receivers.php
http://www.digitalradiotech.co.uk/dab/dab_radios.php


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