[BC] Does a Glut of New Signals Mean More Revenue?
Peter Smerdon
psmerdon
Sun Aug 27 00:40:19 CDT 2006
Dana,
They are two different algorithms (codecs) for different applications.
MPEG2 (I'm assuming you mean MPEG-1 Layer 2) was developed a l-o-n-g
time ago for use with relatively high bitrates.
It is regarded as "imperceptible" at 256kbps (tho' some say 192kbps is
fine).
Conventional wisdom is that "MP1-LII" is not suited to low bitrate use -
and a lot of testing by European broadcast authorities confirms this.
MP1-L11 is used in Eureka 147 - "EuroDAB" and the UK has a lot of DAB
stations at 128kbps (and lower!) and there are a lot of complaints about
artifacts from the enthusiasts.
HD Radio uses a totally different algorithm (codec) - ISTR it's now a
close cousin of AAC (remember I'm in Australia - so I'm not dealing with
this stuff day-to-day).
AAC is much newer, and was designed for the much lower bitrates. I
recall its "sweet spot" is between 96 and 64 kbps (but I'm open to
correction on this).
AAC will always sound MUCH MUCH better at 48kbps than MP1-LII.
Though there are variables to take into account, like the quality of the
encoder code. I've heard MP1-LII mono audio at 64kbps go from "not good
enough for cueing purposes" to "good enough to put to air" (for 3 mins
on AM)with a firmware upgrade to a particular ISDN codec.
Cheers,
Peter Smerdon.
Dana Puopolo wrote:
> I'm using a 57 kbit mono MPEG2 stream for an STL. What I can't understand is
> that some here who have heard it say it's barely usable for AM, yet these same
> people claim that 48 kbit stereo IBOC sounds great.
>
> The numbers simply don't make sense.
>
> -D
>
--
=============================
Peter Smerdon.
Radio 3mp - Easy Listening
sen-1116 - Let's Talk Sport
Melbourne, Australia.
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