Digital Radio Samples

To download the files, right-click the link then click Save Target As.

The above samples require an MPEG decoder such as Winamp for playback. To download Winamp, click here (the link goes to a page where you can download Winamp Version 2.91 because Version 3 has memory leakage problems which aren't present in Version 2.xx of Winamp).

When you listen to these samples you must consider the playback system you are listening on. A cheap soundcard and cheap PC speakers will not give a fair representation of digital radio's audio quality. If you don't have a decent sound card connected to a half decent hi-fi system then the best way to listen to these samples is to download them and burn them onto a CD-R and listen to them on a CD or DVD player that is capable of playing MP2 files (quite a lot of DVD players that are capable of MP3 playback can play MP2 files back if you rename the .mp2 file as a .mp3 file). Alternatively, you could play these files back and record them using your soundcard as a .WAV file (CD format) and then burn them onto a CD-R and play them back in any CD player.

The best way to compare the audio quality of samples is to either use a decent pair of headphones or to turn the volume up to a highish level  on your hi-fi (but not so high as to cause distortion).

Usually, the 128kbps stereo music stations have the following characteristics (98% of stereo music stations on DAB use 128kbps):

• Very poor top-end (high-frequency) response (because using 128kbps instead of the preferred 192kbps cuts off the higher frequencies)
• Dull sound due to the poor top-end response
• Muffled sound due to the lack of accuracy at which the audio samples are encoded at due to the low bit rates used
• Lack of stereo image and instruments all meld together to form a messy, muddled "wall of sound"
• Swishy vocals (listen to the Life sample below to hear this sound)
• Sibilant speech (when people pronounce 'ss' or 'sh' sounds they come out sounding lispy)

The above problems with audio at 128kbps disappear when higher bit rates like 160kbps and 192kbps are used instead. 

Basically, the following always holds:

With everything else being equal, a higher bit rate sample will have a better audio quality than the same music encoded at a lower bit rate.

So, for instance, Radio 1 on Freeview will always sound better than Radio 1 on DAB because Radio 1 on Freeview uses a bit rate of 192kbps whereas on DAB Radio 1 is transmitted at 128kbps, and apart from that everything else is the same.

I've read many mis-conceptions about the audio quality of digital radio, so here's some facts to hopefully educate people so that they can avoid these mis-conceptions:

• DAB, Freeview, digital satellite and digital cable all use the same MPEG1/2 Layer 2 codec (or MP2 for short)
• DAB, Freeview, digital satellite and digital cable do not use MP3; MP3 is a superior codec to MP2 as used on DAB, DTT, DSat etc
• Broadband internet radio stations sound better than DAB stations even though they use the same bit rate of 128kbps because internet radio stations use MP3 whereas DAB uses the inferior MP2 codec
• MPEG-1 and MPEG-2 is not the same as MP1 or MP2. MP1 stands for MPEG1/2 Layer 1, MP2 stands for MPEG1/2 Layer 2, and MP3 stands for MPEG1/2 Layer 3
• Stations on DAB don't sound better than the same stations on Freeview or digital satellite, if they do then there's something wrong with their Freeview or digital satellite receiver or the analogue output circuits of their Freeview or digital satellite receivers aren't very good, but this does NOT mean that the audio quality is better on DAB, the opposite is in fact the truth for the BBC stations
• FM with good reception sounds far better than DAB
• DAB is not robust against interference. You don't get hiss as you do on FM, but instead if there is interference the signal "drops out", and you either get no signal at all or a sound that resembles bubbling mud (listen to the BBC GMR sample to hear this bubbling mud sound), reception of digital radio on Freeview is far more likely to be stable if you can receive Freeview in the first place.
• Audio quality at a certain bit rate is not constant - the audio quality goes up and down depending on how easy a track is to encode.

(if the Freeview samples don't play in Winamp then if you have an mp3pro decoder then turning this off from being the default decoder should allow the files to play, please email me with with the details of your MPEG audio player if you still have problems playing them back)

* an AAC/MP4 input plug-in for Winamp is available to download here: http://www.rarewares.org/files/aac/in_mp4.zip and various AAC encoders and decoders are available here: http://www.rarewares.org/aac.html 

** FLAC is a lossless audio codec (as opposed to lossy codecs like MP2, MP3 and AAC), which means that if you encode from WAV to FLAC format, and then decode the FLAC file back to WAV format, the resulting WAV file will be identical to the original WAV file, which is why it is called 'lossless'. If you encoded a WAV file to a lossy codec and then decoded back to WAV then the resultant WAV file will not be identical to the original. You can download FLAC from here: http://mikewren.com/flac/ 

The above samples were recorded using a Modular Technology PC card for DAB, a Hauppauge DEC2000-t receiver for Freeview and a Denon TU260L analogue tuner for FM (the Denon is only about £90 from places like Richer Sounds). The DAB and Freeview samples were recorded directly to a hard drive so that the audio is the raw MP2 data, which is exactly the same as the audio leaving the broadcaster's offices assuming no transmission errors. A normal TV aerial was used for Freeview, a single-element DAB dipole and a single-element FM dipole for DAB and FM respectively, both of which were indoors. The FM samples were sampled by my Terratec EWX24/96 sound card and encoded to highest quality variable bit rate (VBR) MP3.