What exactly is DVD-Audio?
We've all heard of DVD-video, but what's DVD-Audio - well I'll tell you! It's a newly emerging sound format th...
The CD as we know it was invented back in the early 80’s – about 20 years ago. It’s time it had an upgrade. DVD-Audio is one of two new competing high quality audio formats now available (the other being SACD). This feature will give you an overview of the DVD-Audio format, how it works and what can be expected from it. This feature does not compare DVD-Audio and SACD.
An Overview – the easy to understand part
DVD-Audio utilises the vast storage space available on a DVD to bring a new level of audio quality into ordinary people’s homes. This can be normal stereo as with normal CDs, or true multi-channel sound as with DVD-Video soundtracks. DVD-Audio can also contain a small amount of video. The current specification supports up to 16 graphic stills per track. These can be pictures, lyrics, track information – you name it. However DVD-audio is not capable of containing the audio and video from for instance, a concert. Special equipment is required to listen to a DVD-Audio soundtrack. Often DVD-audio discs also contain an audio track compatible with normal DVD players. This will be provided in either normal stereo as with a CD, or in 5.1 surround like many of the available DVD movies. Generally all DVD players can play a DVD-Audio disc, but only a few can play the DVD-Audio part of the disc. DVD-Audio packaging is often marked with the different soundtracks available on that particular disc.
What sort of system do you need to appreciate this format?
I guess this falls into two areas – can you play a DVD-Audio disc on your current setup, and if not what do you need to truly appreciate this audiophile quality format?
Most DVD-Audio discs should be compatible with a normal DVD player. To provide compatibility across the range of players, most discs ship with an additional Dolby Digital (and sometimes DTS) audio track as well as the high bit rate DVD-Audio.
However, a DVD-Video player will not recognise and play the ultra-high fidelity audio tracks on a DVD-Audio disk. To play these tracks, a DVD player is required that meets the DVD-Audio specification. These players can be identified by the DVD-Audio logo.
DVD-Audio discs are NOT playable on a CD player. Like a normal DVD-Video player, currently PCs cannot play the high quality audio stream on these discs either, but since they can be compatible to the DVD-Video standard, they should be able to play the normal Dolby Digital or DTS (if present) soundtracks.
To listen to DVD-Audio discs, your DVD-Audio player needs to be connected to your amplifier via the analogue outputs on the player. This is because at present there are no amplifiers capable of decoding the high bit rate signal, so instead the player decodes it and just passes the analogue signal to the amplifier. If the Dolby Digital track was preferred then the digital output from the DVD player could be used instead as home cinema amplifiers can decode this signal. It’s worth noting that if you have a DVD-Audio player, it will default to the high quality DVD-Audio soundtrack without even offering the option to listen to the lower quality Dolby Digital mix.
However, a DVD-Audio player can also be used with a two channel stereo system. Many DVD-Audio disks will contain 2 channel stereo sound tracks already. However for those disks recorded only in multi-channel PCM, the DVD-Audio players will down-mix the multi-channel recording into stereo (if the disc provides it’s own stereo DVD-Audio mix it is often encoded to not allow the player to down mix the main audio track). Why would you want to listen to high quality multi channel audio through two speakers I hear you ask? Well, what if you haven’t got 6 speakers yet and you want to hear all the music? Or if you want to listen to all the sound through the headphone socket on your DVD-Audio player? That’s what down-mixing is for. Basically it takes all 6 channels of sound, and combines them into 2 channels for you. It’s very convenient for both of the above scenarios.
Currently neither optical or coaxial digital connectors can shift data at a fast enough speed to output DVD-Audio, so until DVD players start using firewire connectors, the conversion to analogue will have to be done inside the DVD-Audio player, rather than in an amplifier.
Do DVD-Audio discs contain Region codes like their DVD-video counterparts?
DVD-Audio does NOT include Region Coding. Therefore, all DVD-Audio discs will be playable on all DVD-Audio capable players. However, many DVD-Audio discs include DVD-Video components to provide compatibility with DVD-Video players. Those "objects” or “files" (usually Dolby Digital or DTS audio and short videos) could be restricted by Region Codes and may not be playable on all DVD-Video players. Therefore be warned if you do not have a multi region DVD player and are thinking of importing a DVD-Audio disc.
What is the DVD-Audio specification? – the more complicated bit
Although DVD-Audio supports Dolby Digital 5.1 and DTS it is not trying to compete with DVD-Video music discs it is trying to tear you away from CDs. You see DVD-Audio is for people who love music. The discs can contain full multi-channel 5.1 surround sound, recorded with a range of frequencies that are over 4 times greater than that you might find on a CD. It also has a greater “dynamic range” which means that gentle sounds are even quieter and loud sounds can be even louder producing a more realistic, involving, life like sound.
However, the Dolby and DTS soundtracks on a DVD-Audio disc are optional, so if you do not have a DVD-Audio compatible player then make sure the disc contains a soundtrack your player can use.
The following table contains the technical stuff, comparing DVD-Audio to normal CDs.
4.7Gb - Single layer
8.5Gb - Dual Layer
17Gb - Double Sided Dual Layer
Up to 6
0 - 96kHz (max)
5 - 20kHz
Sampling Rate - 2 channel
44.1, 88.2, 176.4KHz or
48, 96, 192KHz
Sampling Rate - multichannel
44.1, 88.2KHz or
Sample Size (Quantization)
12, 16, 20, or 24 bits
Maximum Data Rate
DVD-Audio is encoded in the same way as a CD, using PCM or Pulse Code Modulation. To represent an analogue signal in a digital format, two items from the above are important – “Sample Rate” and “Sampling Size”. You will often see these represented as 2 numbers such as 96/24 which means a sampling rate of 96,000 samples per second, taken at a 24 bit sampling size.
Sampling Size is the number of data bits used to represent the analogue audio as a digital signal each time is it sampled. The more bits used, then the closer the digital representation of the analogue waveform will be.
The sampling rate is just the number of samples taken per second when converting the analogue signal to digital. A higher "sampling rate" allows for higher frequencies to represented.
Data Rate is the maximum amount of data the player takes from the disc in one second. You can see that DVD-Audio can take up nearly 7 times more space than the equivalent CD.
DVD-Audio can be compressed onto the disc. This was done because DVD-Audio uses up such a large amount of space on a DVD. However the compression used is lossless. It is called MLP which stand for Meridian Lossless Packaging. It is lossless which means, even though it compresses the data on the disc, none is lost via this form of compression. Take the example of a Windows Bitmap file. If this is turned into a JPEG file and back again to a Bitmap file, it will be smaller than before. This is because the JPEG compression format is lossey. Parts of the data are removed to reduce the overall size. The mp3 audio format is also lossey. For true high quality audio, using a lossey compression format would ruin the music, which is why MLP is used.
The Wrap up – end of the complicated bits
That’s it. If you are unsure of DVD-Audio but are interested I would suggest you find your local home cinema retailer and arrange a demo. If at all possible, find out what DVD-Audio discs they have available for demos, and try and get it on CD to take with you. Listen to a couple of tracks of the CD on their DVD-Audio setup first, and then switch to the DVD-Audio disc. I’ll be very surprised if you don’t fall over, and leave with a brand spanking new DVD Audio player!
Editorial by David Beamish