- Written by Steve Smallcombe
- Published on 25 January 2008
There is no question that High Definition DVDs are wonderful and give the home theater enthusiast access to not only to higher definition video, but higher definition audio as well. Unfortunately, as most readers know, there is a format war for high definition DVDs with two competing standards, HD DVD and Blu-ray. Although Warner's recent announcement on the eve of 2008 CES may swing the balance of power significantly in the direction of Blu-ray, there are still many who may well end up with, at least for now, two high definition DVD players incorporated into their home theater system. That is the case for me, as I have a Toshiba HD-XA2 HD DVD player and a Panasonic BMP-BD10AK Blu-ray player. To further complicate things, there are several high definition audio formats that can be found on high definition DVDs of both types, as well as the more familiar Dolby Digital and DTS 5.1 tracks found on traditional DVDs.
This review first outlines the various methods of accessing these high definition codecs, which depends on the vintage and capabilities of the various components involved, and then describes in more detail, a switching component, the Zektor CVS4 ($479), that I have used to access HD audio tracks. My setup has the two DVD players mentioned above and an Anthem D1 Surround Sound Processor (SSP) that does not have HDMI inputs.
High Definition Audio Codecs
Of particular interest to those wanting the best possible sound from their High Definition DVDs, are the higher definition codecs that offer better (more) audio information with higher bit rates and/or no compression. Various perceptual encoding schemes or compression algorithms, e.g., Dolby Digital, DTS, MP3, have been used for years to allow more audio to be stored using fewer bytes of storage on the DVD or iPod, etc. The idea behind compressed audio is to only store the information that the user can perceive and not store information that the user will not notice is missing. One can argue which compressed formats lose less discernable information, but information is missing or lost in all such compressed formats. On the other hand, uncompressed formats, or formats where the original waveform can be reconstructed are often referred to as "lossless". Examples of these new higher definition audio codecs include and/or are labeled on the DVD package as English 5.1 uncompressed (48 kHz, 24 bit), English 5.1 PCM (Uncompressed), Dolby TrueHD, DTS-HD, and to a lesser extent, Dolby Digital Plus.
The simple fact is that these new high definition formats do sounds better and are worth some effort and expense to get them working in your home theater system if you have a high definition DVD player.Accessing these improved sound formats will typically require the user to select the desired format from the languages or audio options menu on the DVD, and, here is the rub, get the relevant information into your SSP or receiver in a format that is recognized and can be processed, amplified, and sent to the various speakers. These codecs are not available over the more common TosLink (optical) or coaxial digital connections we have used for years to send Dolby Digital and/or DTS soundtracks to our receivers or SSPs. From the beginning, there was disagreement between Dolby and DTS about where the codecs would be decoded, e.g., decode in the DVD player and transmit generic information, e.g., multi-channel PCM (Pulse Code Modulation) to the SSP or receiver; or transfer the un-decoded information to the SSP in bitstream format, and let the SSP do the decoding. Today, decoding can happen in either the DVD player or the SSP, with information being transferred via either an HDMI cable or multiple analog cables. The three common options for accomplishing this are outlined below.
Improved Audio via HDMI 1.3: If you have a very recent receiver or SSP that supports HDMI 1.3a, such as the Integra DTC-9.8, and a high definition DVD player, you can likely use an HDMI connection between the DVD player and the SSP to send audio information for these higher definition codecs in a bitstream for decoding in the SSP. With this setup your SSP with HDMI inputs can now not only serve as an HDMI video switch, but can also switch and decode the bitstream information for these lossless codecs from multiple players. Notice, that the above statement was not definitive, but used the word "likely". While we may wish to think of the various HDMI levels or releases, e.g. 1.1, 1.2 and 1.3, as standards or "rules" with which the various manufactures wouldc omply, they are actually more like guidelines, to paraphrase one of our favorite movies. As was made very clear at a recent HDMI press conference, ask not whether a component is 1.3a compliant, but rather check the specifications of the components on both ends of the HDMI cable whether or not they support the particular feature of HDMI 1.3 that is of interest. Not all components claiming 1.3-compatibility implement the entire feature set. One also has to make sure that the HDMI cable is capable of supporting the combined bit rates of all the new audio and video features potentially involved with the full 1.3a feature set. Not all cables with an HDMI connector are capable of the same bit rates or levels of performance.
Improved Audio via HDMI 1.1: If your receiver or SSP supports HDMI 1.1 and has implemented the ability to receive and process audio information in a multi-channel PCM format via an HDMI connection to the DVD player, e.g., the Anthem Statement D2 SSP, and your high definition DVD player can decode the codec of interest and output the audio as multi-channel PCM via HDMI, then, again, you are in good shape for getting the most out of the new audio formats present on high definition DVD players. Note that not all SSPs and receivers with HDMI inputs and HDMI switching can process multi-channel PCM via HDMI, but if yours will, then you can also enjoy lossless audio from the new codecs from one or more DVD players.
Improved Audio without HDMI: If your receiver or SSP does not have HDMI inputs, you may have already added an external HDMI switcher to allow multiple sources to provide video for your projector or display via HDMI. This is my situation. I added a Display Magic 5XI HDMI switcher from Better Cables some time ago to accommodate HDMI inputs from my DISH receiver and HD DVD player, as well as my laptop and the Accupel video test signal generator I use to test video projectors. When it came to adding a Bluray player, no problem, as I had a five-input HDMI switcher. Accessing the higher definition audio codecs without the HDMI capabilities listed above in your receiver or SSP, obviously requires a different approach. Fortunately most receivers and SSPs made for quite a few years now have 5.1-channel analog inputs. In the past, these inputs were commonly included to accommodate outboard processors and/or DVDAudio and SACD players where the audio decoding was done in the DVD player, while the relevant audio information for the 5.1 channels was sent via analog connections between the DVD player and the SSP or receiver. If your receiver or SSP has 5.1 analogi nputs, you can likely use these analog inputs to access the new audio codecs, providing your DVD player(s) can decode these codecs and output them via 5.1 analog audio outputs. Fortunately, many of the older and/or somewhat more expensive new high definition DVD players can do just that, as is the case with my Toshiba HD-XA2 HD DVD player and Panasonic BMP-BD10AK Blu-ray player.
Two DVD Players, One SSP Input: The obvious problem, as most may have guessed by now, is two high definition DVD players with two sets of 5.1 analog audio outputs, but only one set of 5.1 inputs on the SSP. My first solution to this problem was to run six analog cables between the SSP and one of the DVD players, enjoy that movie, and then move the six cables to the other player to play a movie in the other format. This was not a good solution, but it gave me enough experience with the high definition audio codecs to be sure that they were worth the trouble. Of course I could have upgraded my SSP to an Anthem D2 or a different SSP that supports the relevant HDMI 1.1 or 1.3 features, but I was not quite ready to make that plunge. I was actually quite happy with my current setup, especially if I could find a low cost way of switching 5.1 analog cables. To make this two DVD setup work, I needed a high quality switch for six analog channels.
Fortunately, a bit of searching online led me to Zektor and an array of products that are perfect for solving this and similar problems, the CVS4, and the lower cost HDS4.1, as well as the MAS7.1. The CVS4 and the HDS4.1 are listed on the Zektor website as a "High Definition Component Video Switcher" that also switch composite video, as well as analog stereo and digital (optical and coaxial) audio signals.This obviously was just I needed to switch 5.1 analog audio between my HD DVD and Blu-ray DVD players. The CVS4 and HDS4.1 are very similar, with the main differences being that the more expensive CVS4 ($479) comes in a metal case, black, or brushed aluminum, while the lower cost HDS4.1 ($259) comes in a black plastic case. The MAS7.1 ($599) is a three input, one output combination HDMI and 7.1 analog audio switcher, and could be ideal if you need HDMI as well as analog audio switching for your setup. I bought the CVS4 as it was a bit nicer looking than the HDS4.1, and the HDS4.1 was out of stock at the time I ordered. While the MAS7.1 was also attractive, I already had a good HDMI switcher and felt it was more convenient in my setup to have more than three HDMI inputs.
The front panel of the Zektor CVS4 is quite simple in appearance with a power toggle and buttons to manually select one of the four inputs. There are also LEDs indicating which of the inputs is selected. A window to receive IR signals and an LED indicating IR reception complete the front panel.
Front Panel Programming
One can start to appreciate the elegance with which the CVS4 is designed by noting that the front panel LEDs have four possible modes of operation. They are (1) bright with change of input, but automatically fade to dim after 4 seconds of inactivity; (2) always at the bright level; (3) always at the dim level; or (4) off. Furthermore, the intensities of both the bright and dim levels can be user-defined using the front panel controls! One can only wish that the designers of all A/V components might have the respect for the problem of LED light pollution in a home theater that obviously the people at Zektor do! The elegance of the design becomes even more apparent with the Zektor's programmability of the IR control for various inputs and power, as the Zektor units can be programmed to respond to various IR codes from almost any remote control rather than visa versa.
The CVS4 and other Zektor products feature a unique Intelligent-IR(tm) learning mode where you put the component into the learning mode, rather than the remote control, in this case by simply pressing the power button for four seconds followed by the "1" button on the front panel. Then you pick a remote control that you are not using (I had several), or define a device on a universal remote control that is not in your system, and simply hit the 1,2,3,4,8,9, and 0 keys in that order. The Zektor unit will now use those IR codes to select the four inputs as well as discrete codes for on and off (8 and 9) and a power toggle (0). This means that one can easily adapt the Zektor to work in your system without necessarily having one more now redundant remote control to store once you have programmed your universal remote. One can also download a cvf file with the default IR codes stored in the popular Pronto format.
The HDS4.1 actually ships without a remote control, while a small remote with discrete buttons for each of the Zektor products ships with the CVS4. This same remote is available as an option for the HDS4.1, but I can't see why anybody would need it, given the ease with which the unit itself can be programmed to respond to virtually any IR code.From the front panel one can also define the initial state the unit will assume when it is first powered up, as well as potentially disabling the front panel to protect against little fingers pressing buttons. To me, this level of customization for such a "simple" component as a switcher, was amazing and very welcome. This is not just elegant engineering for elegance sake. It would really seem to come from Zektor's understanding the varied needs of home theater enthusiasts, and their ability to find simple and effective ways of meeting those needs.
Rear Panel Inputs and Outputs
The rear panel of the CVS4 has four inputs, one output, switching of six analog as well as digital (optical and coaxial) signals, plus an RS-232 port and an IR control jack. Of course, the area of interest to me for incorporating multiple high definition DVD players into my system is the six analog connections for each input. While these inputs are colored and labeled for convenience as a component video switcher, the manual makes it clear that all six channels are of equivalent bandwidth and functionality, and may be interchanged as desired; or as they also suggest, used to switch 5.1 analog audio signals. The CVS4 passively switches analog signals using high quality relays with gold clad, silver-palladium contacts, and therefore offer in a switch, the equivalent of physically swapping cables. I had looked at other component video switchers, but they were typically based on active circuits, and although they also would switch six analog signals, I was not convinced an active circuit designed for video signals would pass audio signals very accurately. Quite the contrary. Relays are a much better approach, especially if they employ break-before-make switching logic, as is the case with the Zektor. Relays really don't care what the signal is, or which way it is going, as long as it is within the bandwidth of the relay, in this case 200 MHz (-3dB), which is certainly good enough for audio!
The CVS4 can also be used in reverse as a one input, four output switcher if desired. Zektor claims the 200 MHz bandwidth (-3 dB, 70 MHz, -1dB) will handle all existing HD video signals if you want to use this unit for component video switcher. In that case, also of interest will also be the digital audio switching capability of the CVS4, which switches one output between four optical or four coaxial inputs. In keeping with Zektor's quest for flexibility, coaxial inputs are converted to optical outputs and visa versa, so one could have mixture of optical and coaxial inputs to the unit, but a single connection of either type to the receiver or SSP.While I have not used the RS-232 port or the IR input on the CVS4, both deserve a bit of explanation. (The HDS4.1 has neither the RS-232or IR ports.) Zektor calls their serial protocol KISS, or Keep it Simple Serial. I won't go into detail, but reading the specifications certainly suggest the engineers at Zektor have a lot of experience in this area and have tried to keep their protocol as simple and reliable as possible. Likewise, the IR control port will recognize the same IR codes as the front panel IR sensor with a signal voltage range of 3 to 12V in either unmodulated or modulated formats, with a modulation frequency ranging from 25 kHz to 250 kHz.
Installation and Use
As mentioned above, I was (and am) pretty happy with my current setup that includes an Anthem Statement D1 SSP. Since my DVD players output 1080p over HDMI, and since I have an external HDMI switch, I haven't felt compelled to buy or upgrade to an SSP with HDMI switching and video processing. Although I was not ready to upgrade SSPs, I did want access to the higher definition audio codecs on both Blu-ray and HD DVD players, and I wanted to do this with minimal expense if possible. Moving the six analog cables between my two DVD players worked, but certainly was not convenient, to say the least. When I found the Zektor HDS4.1 on line for $279, this seemed like a real solution my dilemma. For the reasons also mentioned above, I ended up with the somewhat higher cost CVS4 and I am extremely pleased how simple it was to install and easy to setup and use.
Since I am not currently using the IR or RS-232 ports on the CVS4, I have no doubt that the lower cost HDS4.1 with its plastic case, but otherwise identical switching specifications, would also have served me just as well. In practice, the CSV4 installed easily, but one does need to be careful to make sure that the inputs and outputs for each channel get from here to there without being reversed, i.e., inadvertently reversing the left and right surround channels. Perhaps this is obvious, but it does require some care given the number of cables and connections, but fortunately only needs to be done once, not every time you want to watch a DVD of a different format.I have now watched and listened to a number of high definition DVDs in both formats, and again there is not question in my mind that these codecs that use a higher bit rate and or uncompressed PCM for the audio do sound better. It is actually pretty easy to switch audio formats, essentially languages, in the middle of the DVD and repeat the same scene. This setup also give me a way to play my collection of DVD Audio discs, as that format is supported by my high definition DVD player.
There is one codicil about this approach however that I should mention; switching multiple sets of six analog cables involves LOTS of analog cables, eighteen to switch two DVD players and to connect to the SSP. I looked in my storage boxes before I bought the CSV4 and was surprised I had that many good cables sitting around, but then again, I used to have audio RCA cables connecting preamps to amps (now XLR), and at one point had two connected processors and cables to enable DVD audio via exactly the same 5.1 inputs and outputs used here. As I already owned eighteen analog audio cables of reasonable quality, the Zektor seemed to be the lowest cost approach that would accomplish my goals.
If you have to buy that many audio cables of reasonable quality, then that could easily change the economic equation, and upgrading receivers might be a better deal. At least you have options. Another point to consider before deciding on this 5.1 analog input approach is determining what sound processing options your SSP or receiver allows with the 5.1 analog channel input. Ideally, you will want to have access to all the bass management, THX processing, EX or 7.1 processing, music processing modes, etc., that one might use for watching a movie or listening to music using Dolby Digital via a digital input.
For instance, when I tried to select EX processing fo rone of the High Definition DVDs whose jacket suggested that the rear channel information was so encoded, I was disappointed to find that the software in my D1 did not support this mode of playback with the 5.1 analog inputs, only the digital inputs.This was only a temporary setback however, as I then downloaded upgrade my D1 to the latest software, and this allowed any processing modes available for the digital inputs to be used with the 5.1 analog inputs, thus allowing movies that were EX or 7.1-encoded to be properly played back using the 5.1 analog inputs.
It should also be noted that some DVD players, e.g., my Panasonic BMP-BD10AK Blu-ray player, have eight (7.1) analog outputs, not six. One might also remember that the Zektor HD7.1 supports 7.1 switching using eight analog channels. Since my SSP only has six analog inputs, I didn't really worry about switching eight analog channels, but if your SSP does support eight analog inputs, you might want to consider the Zektor HD7.1.In terms of setup, if your two DVD players have vastly different volume level or lip sync requirements, you may need to adjust these things for each player individually. Otherwise, I suggest that you leave all the speaker setting in the DVD setup menu at Large and the distances set to be the same, and adjust the room/speaker/subwoofer related parameters in the SSP setup for the 5.1 analog input. You will also need to tell your DVD player(s), via their system setup menus, to decode the various audio codecs and to output them via the analog outputs, not the HDMI output.
The Zektor CVS4 and the lower cost HDS4.1 are very versatile four input/one output switchers for analog and digital signals (optical and coaxial). Each input supports switching of six analog signals, and these six signals could either be component video, composite video and stereo signals, or six analog audio signals (5.1) in support of higher definition audio codecs now available on high definition DVDs. Since analog signal switching in the Zektor is based on high quality relays, not active circuits, it really does not matter what sort of audio or video signals are being switched. The Zektor products are also amazingly programmable in their approach to control LED lighting levels and other things.
If you have two high definition DVD players for which you want to access the higher definition audio codecs, and your SSP or receiver does not support these audio modes via HDMI, the Zektor CVS4 or the HDS4.1 are a highly recommended low cost solution to what I suspect is currently a pretty common problem. You will have to analyze your own system in terms of how well your SSP or receiver is meeting your current needs, and the proper timing of your next upgrade in this area. If, however, you want to buy a bit more time for your current equipment, and meet the requirements stated above, then the Zektor 5.1 analog switching approach should work for you as well. I am currently very happy with using the Zektor CVS4 to switch 5.1 analog audio between two high definition DVD players in my system.