| BBC Radio Player Bit Rates14th March 2005 The following table shows the BBC Radio Player's 30 most-listened-to shows along with the bit rates used:
The bit rates listed were those observed after the shows had been
playing for about 15 minutes, because the bit rate initially displayed
is far higher than the actual bit rate due to the buffer filling up
very quickly (when using broadband). Using the above bit rates along
with bit rates observed for shows on the other BBC stations available
on the Radio Player, the bit rates of the Listen Again shows for the stations are as follows:
There's clearly 2 bit rate levels that are usually used, along with the World Service using a significantly lower bit rate than all the other stations. But what's most bizarre is the choice of which radio station uses which bit rate (and hence audio quality, because it is the bit rate that sets the level of audio quality), because the decisions seem to be entirely random and not based on theory at all. For example, it is widely known that speech requires a lower bit rate than music to attain a given level of audio quality, and yet of the BBC's network radio stations, Radio 4 and BBC7 both use the higher 46kbps bit rate, whereas all of the BBC's music network radio stations other than 6 Music use the lower 33kbps bit rate. Given the above findings you have to wonder about the competence of the people that make the decisions regarding bit rates at the BBC, and if you compare the relative bit rates on the different digital platforms with the relative bit rates of the BBC Radio Player then the decisions are either highly hypocritical or simply ineptly chosen because, on digital TV, both 6 Music and BBC7 use a lower bit rate than Radios 1-4, whereas on the Radio Player they use the higher bit rate; and Radio 3 on DAB usually uses 192kbps whereas Radio 4 uses 128kbps and BBC7 only 80kbps mono. A good example of speech requiring lower bit rates than music is voice encoding for mobile phones where the bit rate used for GSM phone calls is only between 13kbps when using the Full Rate (FR) codec down to as low as 5.6kbps for the Half Rate (HR) codec, with the newer Enhanced Full Rate (EFR) using 12.2kbps. Although the bandwidth used for telephony is significantly lower than for broadcasting, such low bit rates are unimaginable for music, or at least unimaginable for music that people could bear to listen to.
Unfortunately, it seems likely that the bit rate levels for the
stations on the Radio Player were set by people high up in BBC Radio
who either have no understanding of audio coding principles and the
result is a hotch-potch of randomly-allocated bit rates that bears no
resemblance to theoretical requirements. Thankfully, the BBC iMP
(interactive media player) will hopefully make these bit rate
allocations academic, because the rumour is that the iMP will use
128kbps WMA9/10 to encode the radio shows, and WMA9/10 is used for
some of the legal music download services (such as Napster and
mycokemusic.com) and if listening
test results are anything to go by then the radio shows on the iMP
should be higher quality than any of the other digital platforms that
the BBC radio stations are available on. But what these bit rate
allocations certainly do is shed some light on the competence of the
decision-makers in BBC Radio with regards to technical decisions, and
I'm afraid they're found to be badly wanting.
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