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New member Username: Baxter77Post Number: 8 Registered: Jan-07 | I purchased an hd dvd player a couple of months ago, and I noticed that many of the hd dvd's list dolby digital true hd and dolby digital plus as the soundtracks. I know that true hd is lossless, and can only be passed through an hdmi/dvi cable. My dvd player is hooked up to my receiver through a digital optical cable so I know I can't experience dolby true hd, so I'm wondering if dolby digital plus is something that I would notice as sounding "better" than standard dolby digital, when being run through the digital optical cable. thanks. |
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Platinum Member Username: Project6Post Number: 14583 Registered: Dec-03 | Different schools of thought on that one Michael. There are those who claim that they can hear a difference and there are those who claim they are the same. Neither camp could claim their's is the right claim. You need to listen for yourself and decide on your own. I could tell you there is a difference but if you don't hear it for yourself, who is to say one of us is right or wrong? But most agree on one thing...they are indeed different, but whether or not one is better than the other is a different matter. The worst are those who claim that the best thing out there is lossless or uncompressed without actually hearing it for themselves. They base their conclusions on data and specs. But oh well...what can you do? Better sounding is a very subjective matter and totally dependent on a lot of factors interacting with one another. You can have the purest source possible for your audio, but if you are using less than stellar performing speakers, such as Bose, or you are using your TV speakers, etc., it doesn't really matter does it? |
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New member Username: Baxter77Post Number: 9 Registered: Jan-07 | Berny, thanks for the response. I was worried this was going to become another orphan post! I guess DD plus is a slightly improved version of DD for those of us who can't pass the audiothrough an hdmi connection. |
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Gold Member Username: John_sColumbus, Ohio US Post Number: 2081 Registered: Feb-04 | Dolby Digital Plus is indeed more than a "slightly" improved version of Dolby Digital. DD+ can max out to 3Mbps (that would be 3 million bits per second) and can yield more channels. Even at this high bitrate DD+ is still considered lossy. This bit rate compares to a max of 640Kbps (640 thousand bits per second) for standard Dolby Digital. In actual practice most DVDs are limited to 384 or 448 Kbps on their Dolby bitstreams, making it a truly lossy audio format. In comparison, CDs are PCM at just over 1411Kbps -- and even this bitrate is seriously lossy. There are only two ways DD+ (and of course, the lossless codecs) can be conveyed to a receiver/processor. The first is by sending the undecoded Dolby Digital Plus or the Dolby TrueHD (or the equivalent DTS) bitrates via HDMI from a 1.3 source to a 1.3 receiver. The second is by letting the source decode these bitrates into LPCM (linear pulse code modulation) where HDMI 1.1 equipment can process that signal. Neither TOSLink (optical) nor S/PDIF (coax) have the bandwidth to carry anything above the legacy DD and DTS bitstreams. There is a piece of good news here, though. When a HD DVD player transcodes a DD+ track to its optical output, it does send Dolby Digital's highest possible data rate of 640Kbps. This is why I have noticed better sound from my HD-A3's optical output on HD DVD discs ("300" comes to mind). It only makes me drool at the new HDMI 1.3 receivers and wonder how awesome these lossless tracks must sound. |
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New member Username: Baxter77Post Number: 10 Registered: Jan-07 | John, thanks for the info, and I'm glad you mentioned you own the HD-A3. I have it too. I was wondering what I should set "digital out HDMI" to in the AUDIO menu of the player? pcm, downmixed pcm, or does it it matter, if I'm using an optical cable for the sound. thanks again. |
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Gold Member Username: John_sColumbus, Ohio US Post Number: 2086 Registered: Feb-04 | I have not paid any attention to the HDMI audio output, because I am feeding the HDMI directly into my older display via a DVI adaptor. Since DVI is video only, I am losing the audio on the player's HDMI output. I think mine is still at the default "Auto" setting, and I think this would be OK if you were using the TV's speakers on an HDMI equipped display. Otherwise, I don't think the specific setting on the HDMI's audio out has any affect on the player's optical output. I do find it curious that Toshiba's manual refers to the player's optical output as "SPDIF". The "coax" connection S/PDIF stands for Sony/Philips Digital Interconnect Format (or InterFace) and the TOS in the optical connection TOSLink stands for its inventor Toshiba. So the inventor of the optical connection has chosen to call its own connection by its arch enemy's acronym for a competing connection system. In any case, it is important that you have the "Digital Out SPDIF" set to "Bitstream." |
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Gold Member Username: John_sColumbus, Ohio US Post Number: 2087 Registered: Feb-04 | As a clarification to my first post above, Dolby Digital Plus can actually max out to 6.144 Mbps and support up to 13.1 channels. The HD DVD format has limited DD+ to 3 Mbps and 7.1 channels. http://en.wikipedia.org/wiki/Dolby_Digital_Plus |