HDMI: Dolby, DTS, Formats

Are Dolby Digital, DTS, and other high resolution audio formats supported by HDMI?

Are Dolby Digital, DTS, and other high resolution audio formats supported by HDMI? Are these the only audio formats that are supported by HDMI? Do I need a specific version of HDMI? These are all very good questions that need to be answered. First let's look at the various HDMI versions and specifications.

First lets talk about what HDMI is. HDMI are the initials that stand for High-Definition Multimedia Interface. HDMI is the newest digital interface standard, supported by the industry, to be used when connecting components of consumer electronics, like high definition television or home theater systems. HDMI allows personal computer manufacturers and audio/visual consumer electronics to bring to the market products that are rich in features and innovative.

HDMI is a signal that is all-digital and not compressed. All the predecessors of HDMI were analog interfaces. Using an analog interface means that a clean digital signal is converted into a “not as precise” analog, and sent out to the T.V, where the signal is translated back again into digital signal to show the screen display. Each time that the signal is converted, the digital signal weakens and loses strength and integrity. This causes some distortion of the quality of the picture. With HDMI the source digital signal is preserved, and there is no conversion of the signal to create the richest, sharpest picture quality available.

HDMI was designed from the very first version to carry 8-channels of 192kHz, 24-bit uncompressed audio, which is more than all the current consumer media formats. Plus HDMI can transmit any currently available compressed audio format. These formats include Dolby, like Dolby Digital EX 7.1, Dolby Digital Plus 7.1, and Dolby TruHD, and DTS, like DTS-ES 6.1, and DTS-HD Master Audio. These compressed formats are the only multi-channel or high-resolution audio formats that can be carried across the older S/PDIF or AES/EBU interfaces. HDMI 1.3 adds extra support for new lossless digital surround audio formats Dolby TrueHD and DTS-HD Master Audio. Plus most existing HDMI sources can output any compressed stream, and the newer HDMI sources can output uncompressed 6-channel, 96kHz audio from a DVD-Audio disk. There are A/V receivers on the market that can accept and process the 6- or 8-channel audio from HDMI.

Two competitive high definition optical disc formats were released in 2006, HD DVD and Blu-ray Disc. These two formats support higher fidelity audio than the old DVD format. These audio formats include DTS-HD Master Audio, Dolby Digital Plus, and Dolby TrueHD. Not all of these formats are mandatory by the BD and HD DVD formats. High definition players may provide a number of different ways to transmit this audio. Currently, the best fidelity is available when the player is set to output LPCM over HDMI when using one of these higher fidelity formats. This requires a preprocessor or audio/video receiver capable of handling multi-channel LPCM over HDMI. While this has been supported by the HDMI spec since version 1.0, not all devices that support HDMI 1.1 support this feature. In the future, it is likely that most devices claiming at least version HDMI 1.1 as a feature will support at least 5.1 LPCM over HDMI.

HDMI version 1.3 will allow for sending TrueHD and DTS-HD over a bitstream rather than LPCM. This would allow a preprocessor or audio/video receiver that has the necessary decoder to decode the data. It is not clear how this will be useful, as all the current players are decoding the audio stream because this is required for interactive audio. The players would either have to skip mixing of interactive audio, or encode the mixed audio to one of these other formats before sending it over HDMI. HDMI 1.3 will support the output of DTS-HD Master Audio and Dolby TrueHD streams for outside decoding by Audio Video A/V Receivers. These are lossless audio codec formats that are used on high definition DVD's and BluRay discs.

The answer to the question is that, yes HDMI will support Dolby Digital, DTS, and other high resolution audio formats. HDMI version 1.3 specifications have included specifications for very high bit rate lossless compressed streams like DTS and Dolby Digital.

What's the differences between DVI and HDMI?

Is there any difference between DVI and HDMI?

DVI stands for Digital Video Interface. HDMI stands for High Definition Multimedia Interface.

Ok, let's discuss what each of these interfaces is and how it works.

Digital Video Interface, or DVI, is actually a predecessor of HDMI. Digital Video Interface was made by the Digital Display Working Group (DDWG). The original design for DVI included conversion of analog signals by converting analog into a digital signal. This was done so that both analog and digital signal monitors could be accommodated by DVI. Data is transmitted by the use of transition minimized differential signaling (TMDS) protocol and provides a digital signal from a PC's graphics subsystem to the display unit.

There is DVI-A and this type of DVI is used for analog signals like VGA. The second type of DVI is DVI-D. This type of DVI is used for digital signals, and this type of signal is the one that all home theater products use and that are intended for consumer home use. DVI-I is the third type of DIV. This type is a combination of DVI-A and DVI-D.

Two levels of performance are supported by DVI-I. These levels are single link and dual link. Currently all home electronics products are designed around the single link standard. A dual link cable, however, is 100 % compatible with a single link cable plus the dual link cable offers the benefit of adaptability in the future for any wide band width applications. DVD-I is a complete, fully digital video transport protocol that is supportive of all digital video formats including 480p, 480i, 540p, 720p,1080p, and 1080i.

High Definition Multimedia Interface is the only uncompressed, all digital audio/video interface that is supported by the industry. Founders of HDMI include manufacturers of leading consumer electronics Panasonic, Phillips, Hitachi, RCA, Sony, Toshiba, and Silicone Image. HDMI is also supported by motion picture producers Universal, Fox, Disney, and Warner Brothers, as well as system operators EchoStar and DirecTV. High Definition Multimedia Interface provides an interface in between any video/audio source, like an A/V receiver, digital television, and DVD player over one cable total, instead of one cable for video and one cable for audio. HDMI will support high definition video, standard video, and / or enhanced video plus multiple channels of digital audio on one single cable. HDMI will also transmit every ATSC HDTV standard and will support eight channel digital audio. HDMI has plenty of band width to spare so any future requirements and enhancements can be accommodated.

HDMI and DVI actually are more alike than they are different. Both of these support the transmission of digital signals. Both DVI and HDMI are based on specifications that are similar, because HDMI specification was derived from the specification for DVI.

There are two important differences between DVI and HDMI. The first difference is that HDMI technology incorporates content security that is called High Definition Content Protection, also known as HDCP. The other huge difference between Digital Video Interface and High Definition Multimedia Interface is that DVI can only support digital video, and HDMI can support audio and video on the same cable.

This leads to another big difference between HDMI and DVI. The number of cables that need to be used and run during installation. With Digital Video Interface at least two cables are needed. One cable is needed to support the video signal, and one cable or cord is needed to support the audio signal, because DVI can only support video, not audio. With HDMI only one cable is needed for the installation. This is because the HDMI can support all formats of digital video plus it can support multiple channels of audio signal as well.

The good news is that despite their differences, a backward compatibility for video exists between HDMI and DVI. Because HDMI evolved from DVI, they are both identical when it comes to video. But remember, DVI can not support digital audio. A good example is an older DVI connection on the source and an HDMI connector to the display. In this case, all that is needed to see the video is an HDMI to DVI cable. However, a separate cable for audio is needed to carry the the digital audio so the sound can be heard.

The best HDMI should look for is Monster Cable. Check it out. Chao.

How can I be sure that my HDMI cables will support higher speeds, deep color, and 1080p?

HDMI cable is capable of providing the highest video resolution that is currently possible. However, an issue that can occur happens because HDMI cable is manufactured of twisted pairs of small-gauge copper conductors, instead of coaxial cable, and this can cause problems when the HDMI cable needs to be run over 50 feet. When an HDMI cable is too long several things may occur. One of these is sparklies, which are where pixels in the images drop out of the picture. Another problem with long cable runs is image degradation to the point that no image is displayed. If the cable is at the length that sparkles or image distortion occurs, then it is too long and an additional device needs to be added to boost or extend the signal. This is because with twisted pair cable it is impossible to keep tight control of any impedance, and without this tight control the signal may reflect along the cable between the signal source and the signal sink, causing interference with the original source bit stream.

Most of the interoperability or image quality issues are not related to the HDMI cable at all, however, but to the software that is used for the device communication and content protection. Quite often, these problems are caused by the HDCP handshaking software. Another common cause is the improper handling of the device capability information that is read through HDMI. It is almost never the HDMI cables that cause the compatibility problems. Non-compliant cables are very rare on the consumer market. The completeness of the HDMI specification has been verified by the fact that there has never been a compliant HDMI cable that is the root cause of HDMI playback issues with compliant devices.

Every HDMI cable is required to support a standard high definition television video signal at the minimum. They have been tested to verify that the cable meets the HDMI specification requirements. This is called a Category one test. HDMI Authorized Testing Centers, also called ATCs, have recently added the equipment to be able to test the cable’s ability to support 1080p, and higher rates, up to the maximum HDMI speeds. Category 2 testing is the name given to the testing done at these higher speeds. Because Deep Color and 1080p are becoming common market requirements, cable manufacturers want their cables verified with this Category 2 high speed test instead of the Category 1 test, so that their cables can be marketed as 1080p verified. Another HDMI testing service is Simplay Labs. They have been performing high speed cable testing for more than a year, and the logo Simplay HD is put on the cables manufactured by cable makers to convey that the cable has this level of quality. This does not mean that a Category 1 tested cable definitely will not support or pass a Category 2 test. A shorter HDMI cable, 3m or less in length, even if it does not have a specific 1080p marking, will probably pass the Category 2 test. The longer that the cable length is, the more demanding the 1080p signal is on the quality of the cable.

The quality of the HDMI receiver chip has a huge effect on the ability of the receiver to cleanly recover and display the HDMI signal. Most, if not all, of the high definition multimedia interface enabled televisions and projectors that support 1080p on the HDMI inputs are created with quality receiver chips that will cleanly recover the 1080p HDMI signal using almost any normal length cable, including those that have only passed the Category 1 test. This cable is not officially guaranteed to support these higher speeds, but in reality these cables usually work fine. This is great for consumers, especially ones who have already purchased HDMI cables before Category 2 testing was easily available. As long as the cables have been Category one tested, they should work just fine for HDMI applications involving 1080p and deep color.

Well I hope you got it.

What do these color coding means on the connectors?

When you look at an RCA or RGB connector, there are a variety of color codings on them. For each color there is a corresponding audio or video signal or format. In the back of all consumer electronics products there are matching color codings. This enables the consumer or professional who is doing the installation to use the color codings and greatly simplify the hook up.

An RCA jack, also called a phono jack, it is used for composite video and stereo audio. The name of the connector, RCA, comes from the Radio Corporation of America.

The RCA connector has been adopted for numerous uses other than the original intention, including power connector, RF connector, and loudspeaker cable connector. It is also commonly used for composite video signals, but this application gives very bad impedance matching. RCA connectors may also frequently be used to carry SPDIF-formatted digital audio, with these plugs orange colored to distinguish them from any other typical connections.

The standard colors for the different signals will be described below. There is a color for 13 different signals. These colors are white, red, green, blue, gray, brown, tan, purple, orange, and yellow. The colors green, blue, and red are repeated once, because these three colors have a place in analog audio and in component video.

The first category for color coding we discuss is analog audio codings on the connector. There are color codings for up to eight different audio connections. For the left connection the coding is the color white. The right analog audio connection has a red color coding. Green is the color coding on the connector for the center audio connection. Left surround audio connections are coded by the color blue. The right surround audio connection is colored gray. There are also two colors that are used to color code surround sound audio connections. The color brown is for the connection that goes to the left back surround audio connection. Tan is the color used for coding the right back surround connection for analog audio. The last color coding for analog audio is the color purple, or sometimes brown, and this color identifies the connector for the sub-woofer.

The next category for the color codes that should be discussed is the digital audio connector. This is the orange colored coaxial cable, and carries S/PDIF instead of analog audio. Composite video is another category, and composite video has a color on the connector that is yellow.

Component video is the last color category that will be covered. RGB stands for red, green, and blue. This term applies to various analog components. These components generally offer the greatest analog video signals that are available in consumer electronics. With RGB there is no limit in resolution or color depth, and no compression is used. RGB has been pretty much ignored, despite the suitability and quality, as it can't be easily applied with Digital Rights Management. In North America RGB was never popular for consumer electronics, as the format S-video was considered adequate.

Other types of component analogue video signals do not use the red, green, blue components, but rather a component that has no color, called luma, in combination with one or components that carry color, called chroma, that give only information on color. Both S-Video component video output (which uses two separate signals) and Y'PbPr component video output (which uses three separate signals) that are seen on DVD players are a good example. By converting video into signals called luma and chroma, this conversion allows for a process called chroma subsampling, a method which JPG images and DVD players use to reduce most storage requirements for video and images.

When component video is talked about today, the Y'PbPr component video scheme is usually what is meant. Many consumer products use this format of color coding, such as DVD players, video projectors, plasma displays, and others. In component video there are three components that have a color coding. The first component is Y, and the color it is coded to is green. Component Pb is associated with the color blue on the color coding. The component Pr has a color coding association that is red.

And we hope that you be able to hook up easily at any given time. Good luck.

Bi-amplification of Loudspeakers

Many audio enthusiasts see bi-amping as an intelligent upgrade for their hi-fi systems. Bi-amping is, simply, the process of "doubling up" on amplifiers in a system and hence doubling available power. This article seeks to point out some important considerations to bear in mind when bi-amping speakers.

Don't Mix & Match
It is crucial when bi-amping speakers that you not mix and match amplifiers. One current trend among audiophiles is to use a solid state amplifier for the bass frequencies, and a tube amplifier for the mids and highs. While this may initially seem logical, there are several reasons why this is a bad idea. Let's take a look at each one independently...

Rise Time
For one thing, two different amplifier designs will inevitably have different rise time specifications (sometimes referred to as event time). For the purposes of this discussion, we will define rise time as the time required for a signal to travel through an amplifier. Depending upon the amplifier circuit, the rise time will vary. Even a small mismatch in rise time will significantly degrade the sound of a bi-amped system.





Consider that in a bi-amped system, there are two possible configurations. The first, pictured above left, is more common. In this scenario, one stereo amplifier is dedicated to the high frequencies, and one amplifier to the low frequencies. The other scenario, pictured above right, is referred to as vertical bi-amping. In this scenario, one stereo amplifier is used to run both the high and low frequencies on one loudspeaker. (Note: In each of these scenarios, obviously two monoblocks could be used in place of one stereo amplifier).

In the case of "standard" bi-amping, any discrepancy in rise times would result in timing mismatches between the low and high frequencies. This sort of mismatch between frequency ranges will degrade the sound substantially because the precision in timing is important to maintain the integrity of harmonics. When a hammer strikes a string on a piano, it is not one frequency which is reproduced, but several - the fundamental and each of its harmonics. In a loudspeaker, it is likely that the fundamental will be reproduced by one driver, and the harmonics by at least one other driver. Hence any timing errors will result in a degradation of tonal balance, and a smearing of the soundstage.

In the case of "vertical" bi-amping, discrepancies in rise times will result in mismatches between the left and right channels. The results will obviously effect imaging, especially soundstage depth. A simple analogy clarifies the scenario: using amps with the same rise time is important when vertically bi-amping for the same reason using cables of the same length is important.

Gain
Another critical consideration is the gain of each amplifier used in a bi-amped system. The greater the gain of an amplifier, the more quickly the amplifier's output will increase as the preamplifier's volume control is augmented. Conversely, as the preamplifier's volume is attenuated, the amplifier's output will decrease at a rate directly proportional to its gain. One simple way to think of the net effect of an amplifier's gain is to associate high gain with bigger "steps" in volume and lower gain with "smaller" steps in volume.

What this means in the case of "standard" bi-amping, is that if the gain of the amplifiers is not matched, the volume of the highs and lows will be changing at a different rate as the volume on the preamplifier is adjusted. In the case of vertical bi-amping, the volume of the left and right speakers will change at a different rate. The effects of these volume discrepancies should be fairly obvious: in the first scenario tonal balance is altered, and in the second scenario the stereo channel balance is altered.

Concluding Remarks
Bi-amping provides many benefits, especially when using lower powered tube amplifiers where the system's overall power output can be doubled easily by simply bi-amping the loudspeakers. Many of our customers at Symphony Sound bi-amp with SET tube amps (2A3's, 300B's, etc.) and enjoy wonderful sound as a result. However, it is important to bear in mind that if certain guidelines are not followed, bi-amping can actually do more harm than good. If careful attention is paid to gain and rise time, it is possible to mix and match amplifiers, but only is unusual circumstances do we feel this is a sensible and prudent approach.

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