Now that the high definition disc format war has come to a close, the number of Blu-ray players in consumer homes’ is steadily climbing. The benefits that a 1080p Blu-ray picture can bring to our television screens at home are undeniable. But the picture improvement over the standard DVD format is only half the story – the other half of the story is in the sound.
Standard DVD Audio Options
Most standard DVDs have entertained us with Dolby Digital or DTS multi-channel soundtracks. Multi-channel sound is usually delivered as a bitstream from the DVD player to an A/V receiver through a digital optical or coaxial cable. Bitstream means that the sound is in its compressed, digital form. The A/V receiver then decodes the bitstream and sends amplified audio to the speakers. Newer DVD players use the HDMI connection to send both video and multi-channel sound to an A/V receiver.
Some DVD players offer on-board decoding of Dolby Digital and DTS, and contain digital-to-analogue (DAC) converters. In this case, the decoded sound is sent through multiple RCA cables to the A/V receiver. But most home theatre enthusiasts prefer that the decoding of surround formats be left to the A/V receiver (more on this later). Using a single cable, rather than six or more RCA cables, will also reduce the clutter at the back of your equipment rack.
While Dolby Digital and DTS are fantastic formats that enable us to enjoy surround sound at home, they are both highly compressed versions of the original soundtrack that we hear at the movies. The 8.5GB (dual layer) storage capacity of the standard DVD simply doesn’t provide enough space for better quality sound.
Blu-ray Disc Audio Options
A dual layer Blu-ray disc can store up to 50 GB of data. This substantially higher capacity allows for not only high definition video but for high resolution audio as well. Besides the good old Dolby Digital or DTS soundtrack, there are four new higher resolution soundtrack formats that a Blu-ray disc can store. These include two lossy (compressed) formats called Dolby Digital Plus and DTS-HD High Resolution, and two lossless (uncompressed) formats called Dolby Digital TrueHD and DTS-HD Master Audio. Finally, Blu-ray releases can also contain an uncompressed multi-channel PCM soundtrack. The new lossy formats are less compressed than standard Dolby Digital and DTS, and hence offer higher fidelity audio. The lossless formats and multi-channel PCM on the other hand, offer audio that’s bit-for-bit identical to the studio master. A quick look at the back of a Blu-ray title should tell you exactly what audio options it offers.
Hook Me Up (Properly!)
Before you can enjoy any of the new audio formats from a Blu-ray disc, you’ll need to configure your Blu-ray player and connect it properly to an A/V receiver or a pre/pro. Unfortunately, this is not as straightforward as we’d like it to be, at least not yet.
The digital optical and coaxial connections do not have the bandwidth or the copy protection required for the transmission of any of the new audio formats. If one of these connections is used, only the standard Dolby Digital and DTS formats will be sent to the A/V receiver or the pre/pro.
Most enthusiasts got their first taste of high resolution audio by connecting the Blu-ray player to the A/V receiver or a pre/pro using multi-channel analogue RCA or HDMI (any version of HDMI will work). This method allows uncompressed PCM audio to be sent from the player to the A/V receiver or pre/pro.
But multi-channel PCM audio is not always included on the Blu-ray title. So how do you get Dolby Digital Plus, DTS-HD High Resolution, Dolby TrueHD and DTS-HD Master Audio to an A/V receiver or a pre/pro? The new formats need to be decoded by either a Blu-ray player or an A/V receiver (or a pre/pro).
Decoding of the new formats inside the Blu-ray player is still a bit of a mixed bag. Early Blu-ray players can’t decode any of the new formats. More recent models have built-in decoders for some, but not all, of the new formats.
If the audio decoding is handled by the Blu-ray player, a PCM version of the sound can be sent to the A/V receiver or the pre/pro using through multi-channel analogue RCA connections or the HDMI plug.
The A/V receiver category has faired much better in the decoding department. Many A/V receiver manufacturers have updated their product line-up to include a few models that can decode all four of the new audio formats. I suspect that by the end of this year we’ll also see higher-end component manufacturers introduce pre/pros that can decode the new formats.
It is important to note that most home theatre enthusiasts prefer for the decoding to be performed by the A/V receiver or the pre/pro, rather than a Blu-ray player, for several good reasons. Many Blu-ray players have inadequate speaker delay settings, bass management and speaker level adjustments. The quality of the decoders and digital-to-analogue converters (DACs) inside a disc player is usually inferior to the DACs in an A/V receiver or a pre/pro. When the audio is decoded inside the A/V receiver, additional processing like Dolby Digital EX or DTS-ES can also be applied to the audio. This allows a centre rear or surround back channels to be derived from a 5.1 channel soundtrack.
To decode the new audio formats inside the A/V receiver or the pre/pro, you will have to configure the Blu-ray player to output the sound as a bitstream, a digital signal. For this to work, both the Blu-ray player and the A/V receiver (or pre/pro) must have HDMI version 1.3 connections. When watching a Blu-ray title, remember to select one of the new audio formats from the audio options. If your components are properly connected and configured, you should see one of the new audio format labels appear on the display of your A/V receiver or the pre/pro.
Is It Worth the Trouble?
If all of these connection options sound a little confusing to you, don’t worry – we were all a little confused ourselves at CANADA HiFi when we first started playing with this stuff. The fact is that things have been made unnecessarily complicated with the new audio formats. However, I strongly recommend taking the time to understand all of this so that you can enjoy the benefits of the new audio formats in your home theatre. Once you discover the high resolution sound from Blu-ray titles, you may find it hard to go back to standard Dolby Digital or DTS. And if all goes well, in time the industry will simplify the ways in which high resolution audio is transmitted from Blu-ray players to A/V receivers and pre/pros. In the meantime, it’ll be up to us (the enthusiasts) to help our family and friends connect their players properly!