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Q. What is the advantage of using HDMI over existing audio interfaces such as analog RCA connectors and digital SPDIF (coax and optical connectors)?
Quality: HDMI maintains the audio in its pure digital form all the way to the amplifier. Analog audio connections are more prone to losses depending on the cabling and other electronics of the audio rendering device. Compared to SPDIF connections, HDMI has significantly more bandwidth, allowing it to support the latest lossless audio formats such as Dolby TrueHD and DTS-HS Master Audio. These formats can not be supported over SPDIF connections due to their very high data rate requirements that exceed the capabilities of SPDIF. Please also see section on HDMI 1.3 for further details on Dolby TrueHD and DTS-HD Master Audio formats.
Q. Do I need v1.3 HDMI to hear the new Dolby TrueHD and DTS Master HD audio content on HD-DVD or Blu-ray players?
No. The Dolby TrueHD, Dolby Digital Plus, and DTS-HD Master Audio can be decoded by the playback device into multi-channel Pulse Code Modulation (PCM) digital audio streams, which is an audio format standard that can be sent over any version of HDMI. In fact, all versions of HDMI can support up to 8 channels of PCM audio at 192kHz, 24 bits per sample.
To do this, consumers should ensure that their playback device (such as HD-DVD or Blu-ray player) is capable of decoding these new lossless Dolby & DTS audio formats into the PCM format on the HDMI output, and that the audio device (such as an A/V receiver) is capable of receiving multi-channel PCM audio over the HDMI inputs. Consult your user manual/product specification sheet to determine whether your device supports such PCM capabilities (we believe that nearly all HD-DVD and Blu-ray players will, but users should confirm this). Devices that support HDMI v1.3 and higher may also offer the option to transport the high definition audio formats as a compressed, encoded stream over HDMI so that the decoding function can be performed by the A/V receiver (whereas the above transport method has the playback device performing the decoding).
Q. What is the difference in quality between listening to Dolby TrueHD/DTS-HD over HDMI, SPDIF (i.e. coax or optical), or analog from the player to the A/V receiver?
HDMI provides the highest quality as it enables the full, lossless audio data of Dolby TrueHD to be transferred digitally to the AV receiver, and enables the A/V receiver to apply its full digital audio processing capabilities (such as bass management, or sound field processing effects) to further enhance the audio quality. SPDIF does not have the ability to support the data rates required by Dolby TrueHD, and thus will not support it. Analog will be lower quality than HDMI due to two reasons: 1) the nature of analog transmission is lossy and will degrade while transported over the cables, 2) many A/V receivers will not apply any digital audio processing to the analog inputs, and in such cases analog signals will be sent directly to the amplifier without the benefit of such processing.
Q. What is the difference between decoding Dolby TrueHD/DTS-HD in the player (i.e. sending over HDMI as decoded PCM) vs. decoding in the A/V receiver (i.e. sending over HDMI as encoded Dolby TrueHD/DTS-HD bitstream)?
There is no inherent difference in quality between Dolby TrueHD/DTS-HD being sent over HDMI as decoded PCM vs. encoded bit stream. All Dolby TrueHD/DTS-HD decoders (whether in the player or the A/V receiver) must be certified to meet stringent quality requirements. However, consumers should make sure that their receivers support the number of incoming PCM channels delivered by their source device (e.g. DVD).
