Blu-ray &Hardware Steven Kippel on 11 Oct 2007

High-def buying tips

High-def buying tips

I’ve been answering a lot of questions lately about what kind of equipment it takes to get the most out of HD DVD and Blu-ray players, so I thought I’d make a list of things to keep in mind when shopping for your new home theater gear. I’m not going to get too specific on equipment brands and models because there is just so much out there and a lot of it is subjective, so I’ll just let you know what to look for in products.

Is 1080p important?

Both HD DVD and Blu-ray offer 1080p resolution. The number represents vertical lines of resolution and the “p” stands for “progressive.” This means 1080p has 1,080 visible vertical lines in every frame. Standard HDTV broadcasts is 1080i where “i” stands for “interlaced.” This means there are 540 visible vertical lines in every frame cycling between even lines (2, 4, 6, 8, et al) and odd lines (1, 3, 5, 7, et al). Video is interlaced for TV broadcast to cut the required bandwidth in half as only half the image is broadcast per cycle (the cycle is 60Hz) with every other frame on alternating lines.

Fixed-pixel displays (including all plasma, LCD, DLP, LCoS and like televisions and excluding all CRT sets) have a set number of pixels in vertical and horizontal planes. The common 720p plasma has 1,366 horizontal pixels and 768 vertical pixels. The TV’s internal processor receives the signal (be it 480i, 480p, 720p, 1080i or 1080p) and scales the image to fit the screen, usually adding a measure of “overscan” to make sure the image fits the screen. A 1080p television receives a 1080i signal and “de-interlaces” the image. What this means is each frame shows the even or odd lines and fills in the other lines with an image approximated from the frames immediately before and after the current frame. This process causes what the industry calls “judder.” An example of the de-interlacing process can be seen here.

The benefit of 1080p is that every frame shows every pixel of that frame. This means all 2,073,600 pixels of the frame are shown on each cycle adding more image clarity and reducing judder. However, 60Hz is the equivalent of 60 frames per second, so a de-interlaced frame is practically imperceptible to the human eye. Only in some scenes would the judder be noticeable, and the majority of people would not notice the difference between 1080p ad 1080i on a 1080p television that properly de-interlaces the image. A caveat is that not all 1080p televisions can de-interlace properly, and some that do are wrong on one input and right on another. I recommend you read reviews from publications like Sound and Vision or The Perfect Vision.

It is my personal opinion that HDTV sets are to the point where they all look relatively good and even a 720p set will astound you if properly set up. Don’t get bogged down in the technical terms and just enjoy the beautiful picture achieved by Blu-ray Disc and HD DVD. DVD has 307,200 pixels which is a fraction of that provided by 1080p sources.

How do I get 1080p from the player to the TV?

There is currently only one way to watch your Blu-ray and HD DVD movies in 1080p, and that is through HDMI. Of course this is contingent on your owning a 1080p display that accepts 1080p signals (early model 1080p DLP sets used “wobulation” technology that wasn’t truly 1080p, so it did not accept 1080p). Your TV’s manual will let you know what input resolutions it accepts. The reviews I previously mentioned will help out tremendously here.

With technology I’m always going to have a caveat, and this is no exception (hell, I’ve already got one in the last paragraph). Not all HD DVD players output 1080p. The lower-end models only output 1080i signals (this includes the Toshiba HD-A1, HD-A2, HD-A3, Venturer SHD7000, and RCA HDV5000 as well as the Xbox add-on). Every Blu-ray player outputs full 1080p, some better than others.

What is the benefit of Advanced Audio Codecs?

There are several new audio formats for Blu-ray and HD DVD. These formats include Dolby TrueHD, DTS-HD, DTS-HD Master Audio, and uncompressed multi-channel PCM. These codecs are considered “lossless” codecs as they do not remove any information from the original audio source. Traditional codecs compress the sound and removes octaves and harmonics deemed “unneccesary” by the compression software. Of course the human ear still hears this sounds and notices when they’re missing. The advanced codecs bring the sound you actually hear in the cinema right to your home with crystal clear dialog and a much fuller sound.

The question is how this benefits you. This is contingent on what gear you have. If you have cheap speakers you will probably not hear a difference because you are limited to the abilities of the speakers you have. As I’ll get to in the next point, what gear you select is the greatest determining factor in your ability to get the most from next-gen formats.

It should be mentioned here for clarity that multi-channel PCM is not a codec at all but is the uncompressed digital signal. PCM is the digital equivalent of an analog sine wave.

How do I hear these new audio formats?

To begin with, it is an unfortunate fact that not every high-def disc has advanced audio, although the majority of them do. Depending on your set up you will have to find which formats you will come across most, and this usually falls on “party lines” between HD DVD and Blu-ray.

Every HD DVD players decode Dolby TrueHD audio, and none of them can decode DTS-HD or DTS-HD Master Audio. HD DVD players decode the 1.5Mbit “core” track from DTS titles making them a higher quality than normal, but it is a “lossy” format still. This audio is output as multi-channel PCM audio over HDMI or as 5.1 analog audio over RCA cables (only the flagship Toshiba models support 5.1 analog audio).

Blu-ray players are not required to decode any of the formats and for this reason many studios are opting to use the uncompressed multi-channel PCM option. However, most Blu-ray players now decode TrueHD and the DTS “core” tracks (this may require a firmware update). Again, this audio is output as multi-channel PCM audio over HDMI or as 5.1 (or even 7.1) analog audio.

As you can see, there are two ways to get the audio from the player to your receiver. If you have an older receiver without HDMI you need to check your manual and see if it supports multi-channel analog. If it does support 5.1 analog, you can use the 5.1 analog outputs on the players to the receiver and plug the HDMI cable directly into your TV (this may require some lip syncing on the receiver).

The other way is to use HDMI. Not every receiver with HDMI accepts audio over that cable, and some that do only accept 2.0 PCM audio, not 5.1 or 7.1 audio. Check your manual to find out if your receiver supports this. If it does support multi-channel PCM audio, you will set your receiver to output “PCM” over HDMI.

With the advent of HDMI 1.3 there is another way to get the audio from the player to the receiver, and this is the way it has been done with DVD for years. A receiver with HDMI 1.3 can accept the advanced audio codecs and decode them on board (check to make sure it decodes both TrueHD and DTS-HD Master Audio). This also requires your player to have HDMI 1.3 and that it supports bit-stream audio over HDMI. This is just becoming available so there aren’t a lot of receivers and player capable of this yet.

What should I look for in a new TV?

The bigger the better. 1080p is a buzzword but don’t be fooled because 720p sets can look just as good or better than some 1080p sets. From a technical standpoint, plasma has the best picture of the new technologies. Of course nothing beats the cinema-like front projection system. This is a very subjective decision, however, so do the homework yourself through reviews and visiting various stores (make the sales associates let you adjust settings).

An advanced feature you may be interested in is 24fps (1080p/24). Some Blu-ray and HD DVD players support 24fps and you might think that sucks because faster is always better, but film is shot at 24fps so it actually looks better because you don’t have judder from 3:2 pull-down. I’ll write more about this later.

What speakers are best?

This is even more subjective than the television question, so I again refer to your own tastes. There are scores of great speaker companies out there, so do your homework and read reviews – I like Stereophile for speakers. What you are looking for is a flat frequency response down to at least 100Hz.

What should I look for in a new receiver?

If you do not have a receiver or you’re looking to upgrade, I would recommend looking for a receiver with HDMI inputs (three or more inputs) that accepts multi-channel PCM audio. If possible get HDMI 1.3 for future use (be careful because some HDMI 1.3 receivers do not accept multi-channel PCM audio and that’s more important than 1.3).

More important than the output rating is the type of amp. A Class-A, Class-B or Class-AB amplifier is what you want to look for. Avoid Class-D amplifiers unless it is an ICEPower amp (these are only available in higher-end products – they’re made by Bang & Olefson). Class-D amps (also known as “digital amp”) are not very reliable when pushing difficult loads (below 6 ohms) and have a harsh sound to them.

Aside from these two recommendations, receivers are also pretty subjective. They all offer myraid features you may never use, so pick which one sounds good to you and has the features you’ll use. If possible find an expert that can help you match your receiver with your speakers.

Any other suggestions?

Don’t wait to get in the game, now is the time to buy. The technologies are so advanced right now that you will be quite happy with anything you can afford, so go crazy. I do often recommend picking up the last year’s models as they’re clearing them out because you can get great bargains on them and the new ones are only marginally better.

If you have any more questions, let me know what they are and I’ll answer them in future articles.

3 Responses to “High-def buying tips”

  1. on 20 Oct 2007 at 4:40 PM 1.1080p/24p explained » Blu-ray, HD DVD, info at WesleyTech.com said …

    […] Lately you have probably been hearing about what’s called 1080p/24 – a new feature that has just become available with the introduction of Blu-ray and HD DVD. I will try to explain this nomenclature in an easy to understand way. To start with, I have previously written about what 1080p is, and I would advise you start there. A quick overview: 1080 is the number of vertical lines of resolution, and “p” stands for “progressive.” This means 1,080 lines are displayed constantly. 24p is what we will focus on in this article. This is a bit more involved, so I will have to go back in time, so please indulge me. Back in the early days of Hollywood film making a lot of standards were developed that we still use today. Among these standards are the Academy film ratio (1.85:1), Cinescope (2.35:1) and 24 frame per second cameras. This frame rate was selected as a balance between natural looking human expression and cost. When making a movie, film stock gets expensive and when you film at 24 frames per second it uses less film than 50 frames per second, less than half the cost actually. With the advent of television new standards were created. Although they used the aspect ratio of film (1.33:1), they chose 60Hz to broadcast television programs (later, in PAL regions they chose 50Hz). Hertz (Hz) is cycles-per-second, so 60Hz is 60 frames per second. Here is where the problem begins. When reproducing a 24fps at 60Hz everything would be sped up and it would look like you were watching the film in fast-forward. To solve this problem, Faroudja created a technique called Telecine. This is often called “3:2 pulldown.” This process creates four film frames for every five video frames and then plays alternating frames three times each and two times each and alternates every four frames. This means four film frames play in the time it normally takes to to play five video frames. However, this process has changed over time. Progressive-scan video and high-definition video has made it so one frame is added to every four (playing one frame three times and the next twice) to make it easier to upconvert and to compress. Both processes cause “judder” but the second causes a bit more. Judder causes the image to jerk a bit. Usually this isn’t much of a problem, but in scenes that pan this judder can be seen and is often distracting. Pioneer was ahead of everyone for years making their plasma televisions operate at both 60Hz and 72Hz. Why does this matter? Let’s do some math. 60 divided by 24 = 2.5 and there is no such thing as half a frame, which is why it is necessary to add an extra frame. 72 divided by 24 = 3 so each frame only needs to be played three times, eliminating the need for the telecine process. Blu-ray Disc is encoded at 1080p/24p right on the disc. HD DVD is encoded at 1080p/30p with a layer of metadata that flags the duplicate frames so if it is output at 24p it will drop all the flagged frames for a 1080p/24p output. Starting this year, several companies have started manufacturing LCD panels with 120Hz refresh rates. 120 can be divided by both 24 and 30 with an even number of frames. Most 1080p front-projectors can natively display 24fps. Pioneer still has the 72Hz plasma panel. Since there are already dozens of Blu-ray and HD DVD players out right now I’m not going to list all the capable players, but this is a spec that is listed, not one of those hidden specs like what version HDMI it has. But what is important is that both the player and television must support 24p for you to get this feature. So is it worth it? 24p has a natural film quality to it that you don’t get from any other digital source. Of course when you are engrossed in a film, the judder usually doesn’t distract from the story on the screen, and that’s what is important. Don’t go out of your way to get 24p unless you’re quite serious on getting the best video possible. I’m convinced you will enjoy Blu-ray and/or HD DVD enough without having to worry about technical mumbo-jumbo. Share this article: These icons link to social bookmarking sites where readers can share and discover new web pages. […]

  2. on 30 Oct 2007 at 4:34 PM 2.mike said …

    I’d like to point out that you’re mistaken about this statement in your article: “The common 720p plasma has 1,024 horizontal pixels and 768 vertical pixels.”
    It’s actually 1,366 x 768. 1,366 is more common place than 1,024. 1,024 x 768 is not HD. You need a minimum of 1280x720p or 1920x1080i.

  3. on 31 Oct 2007 at 9:19 PM 3.Steven Kippel said …

    Thanks for that info! I must have had a specific Hitachi display on my mind at the time. You’re absolutely right.

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