Author: James Courtier-Dutton Date: To: Hampshire LUG Discussion List Subject: Re: [Hampshire] OT:Fwd: Mark Thompson on Media Show on R4 about FM
switch off
2009/6/24 The Holy ettlz <theholyettlz@???>: > On Wed, 2009-06-24 at 12:36 +0100, James Courtier-Dutton wrote:
>> From reading the DAB standards, European Standard 201 980, it seems
>> quite clear that the audio quality of DAB, or DAB+ for that matter is
>> worse than the old FM.
>> It uses 12kHz or 24kHz sampling when we are all used to 44.1kHz CDs
>> and 48kHz DVDs.
>
> I thought Musicam could use those higher sampling rates. Most of the
> distortions I hear on DAB are compression artefacts (sometimes it's
> barely transparent at 192kb/s). This is most likely because back when
> the standard was designed, the cost/performance ratio was much higher on
> DSPs, and an MP2 derivative was the best tradeoff between quality,
> bitrate and computational workload.
>
> I understand that DAB+ is supposed to be based around AAC or something
> and should improve sound quality somewhat.
>
> James
>
The numbers I gave were for AAC, it uses 12kHz or 24kHz sampling rate.
Other modes can use 16kHz and 8kHz and there is even a lower one at
about 4kHz.
Anything recorded at about 12kHz or 24kHz is not ever going to be much good.
Even mp3 files are normally initially recorded at 44.1kHz or 48kHz
samples per second and mp3 supports up to 24bits per sample at the
input.
By the way, .mp3 files are actually mpeg1, layer 3.
AAC is part of the mpeg2, and also supported in mpeg4.
