I thought I'd post this to help out those who have taken the plunge into HD-DVD and/or Blu-Ray, to understand the BASICS of the new HD audio formats that it includes.
The question is, when I pop in a new HD-DVD or Blu-Ray, when I get to the main menu, I've got a choice of several different audio formats. Which one should I choose? Which one will give me the best audio performance?
The selection of available audio formats now can be confusing. Hopefully this will clear up what the different formats are. First, we all know about the legacy audio formats - the competing formats of Dolby Digital and DTS, and the DVD basic audio format of PCM. New formats are simply extensions and new versions of these three legacy categories.
From both Dolby and DTS, you will now see two new formats each. Each company has a new LOSSY format, and a new LOSSLESS format. Because of available disk space, we've needed to have compressed audio streams that take up less space on the disk. Both legacy Dolby Digital and DTS formats were compressed and "lossy", meaning that the encoding was good, but had to lose resolution to save size. Dolby's NEW "lossy" HD audio stream is called Dolby Digital Plus. DTS's is called DTS-HD. Both of these use the same concept, where they are actually core packets of legacy DD and DTS, respectively, but add additional packets of information for additional channels. (2 or even more!!!) So if you connect your new player via legacy connections of optical or digital coax, the player will simply drop out the extra packet, and transmit the legacy core packet to give you legacy DD or DTS. Yes, this still may include 6.1 DD EX, DTS-ES, or for advanced users who know, DTS 96/24.
But the new and cool thing is, we now have the capability to get LOSSLESS audio over HD-DVD and BD. This means that we now can hear for the first time ever the EXACT audio that was recorded and mixed for the movie, with no resolution loss! You'll hear every detail that was recorded. Dolby's all-new lossless format is called "Dolby TrueHD". DTS lossless is "DTS Master Audio". You'll also see a third format, "PCM Uncompressed". According to Dolby, uncompressed PCM is also a true lossless format. So in theory, and it SHOULD also be true in real application, any of these three formats will give you the exact same performance. DTS Master Audio is capable of a higher bitrate, but lossless is lossless--two identical copies of a master should also be identical to each other. (Uncompressed PCM has a larger file size, which can be important to the studio creating the disc)
So we have for new formats:
LOSSLESS: Dolby TrueHD, DTS Master Audio, PCM Uncompressed
LOSSY: Dolby Digital Plus, DTS-HD (and all legacy formats)
So if new HD discs have so much capacity, why even use "lossy" streams? Why not encode with lossless all the time? Well, simply, if you try to include so much info, you still may have to compress to fit it all. Instead of producing different discs for different regions of the world, both BD and HD-DVD now have the ability to create ONE disc to service the entire world. So you may want to include lossless streams of audio in English and Spanish, but to fit extra material, multiple commentaries, and soundtracks in French, Russian, Farsi, German, Portugese, etc, etc, you may have to put those in a lossy track.
Back to the original question--I load up a movie, and I'm staring at the audio selection screen. Which do I choose? As always, the answer is, "it depends"... on what your equipment is capable of, and how it's connected. But in general, the basic rule of thumb is, if you can, choose one of the LOSSLESS formats - Dolby TrueHD, DTS Master Audio, or PCM Uncompressed. Your next best choice is DD+ or DTS-HD.
Within these two categories, which one you choose is up to you. I have my own preference of one brand over the other, feeling that one gives more detail, but try it for yourself. Just like before you may have felt that DTS gave you better audio performance that Dolby Digital, now on the HD formats, you may feel that the Dolby version does better than DTS or vice versa.
Just a bit more on the "it depends", as I'm getting tired--if you have equipment specifically certified to decode Dolby TrueHD or DTS Master Audio, and you have the HDMI connection to support transmission from player to processor, (1.3 for processor decoding, 1.1/1.2/1.3 for player decoding) you can choose those. Even with Uncompressed PCM, you'll need to have a receiver that can receiver PCM over HDMI. Multichannel analog outputs after player decoding can also work.
If one of the lossless formats isn't available, or if your equipment isn't capable of decoding it, you'll have to choose one of the lossy formats. The good news is, even if you don't have equipment capable of, say, DD+, you can still choose it, and get great audio. It just won't be perfect lossless--your player will strip off the "extra channel packet", and give you the core DD or DD 6.1 EX signal, which can be sent over ANY digital connection or decoded and sent over multichannel analog.
Here's a great example of how HD audio can work to your benefit, even with compromises. I have a PS3, which has no multichannel analog outputs, only HDMI and optical for digital audio. I haven't upgraded my A/V processor, as HDMI audio processors are still extremely rare and limited in function, so I don't have HDMI audio with my processor, and am limited to digital optical for HD audio. As stated before, optical S/PDIF is not capable of carrying full HD audio streams. So I put in the U2: Rattle and Hum Blu-Ray disc into my PS3 and choose DTS-HD. The PS3 strips off the extra packet from the DTS-HD stream, and what it put out to my processor is full 1.5 Mbps DTS audio in 5.1 channels. It actually sounds BETTER on my system than my standard-def version of Rattle and Hum, even though it's just legacy DTS 5.1--studios stopped recording full bitrate DTS audio on standard-def DVD's years ago!
The question is, when I pop in a new HD-DVD or Blu-Ray, when I get to the main menu, I've got a choice of several different audio formats. Which one should I choose? Which one will give me the best audio performance?
The selection of available audio formats now can be confusing. Hopefully this will clear up what the different formats are. First, we all know about the legacy audio formats - the competing formats of Dolby Digital and DTS, and the DVD basic audio format of PCM. New formats are simply extensions and new versions of these three legacy categories.
From both Dolby and DTS, you will now see two new formats each. Each company has a new LOSSY format, and a new LOSSLESS format. Because of available disk space, we've needed to have compressed audio streams that take up less space on the disk. Both legacy Dolby Digital and DTS formats were compressed and "lossy", meaning that the encoding was good, but had to lose resolution to save size. Dolby's NEW "lossy" HD audio stream is called Dolby Digital Plus. DTS's is called DTS-HD. Both of these use the same concept, where they are actually core packets of legacy DD and DTS, respectively, but add additional packets of information for additional channels. (2 or even more!!!) So if you connect your new player via legacy connections of optical or digital coax, the player will simply drop out the extra packet, and transmit the legacy core packet to give you legacy DD or DTS. Yes, this still may include 6.1 DD EX, DTS-ES, or for advanced users who know, DTS 96/24.
But the new and cool thing is, we now have the capability to get LOSSLESS audio over HD-DVD and BD. This means that we now can hear for the first time ever the EXACT audio that was recorded and mixed for the movie, with no resolution loss! You'll hear every detail that was recorded. Dolby's all-new lossless format is called "Dolby TrueHD". DTS lossless is "DTS Master Audio". You'll also see a third format, "PCM Uncompressed". According to Dolby, uncompressed PCM is also a true lossless format. So in theory, and it SHOULD also be true in real application, any of these three formats will give you the exact same performance. DTS Master Audio is capable of a higher bitrate, but lossless is lossless--two identical copies of a master should also be identical to each other. (Uncompressed PCM has a larger file size, which can be important to the studio creating the disc)
So we have for new formats:
LOSSLESS: Dolby TrueHD, DTS Master Audio, PCM Uncompressed
LOSSY: Dolby Digital Plus, DTS-HD (and all legacy formats)
So if new HD discs have so much capacity, why even use "lossy" streams? Why not encode with lossless all the time? Well, simply, if you try to include so much info, you still may have to compress to fit it all. Instead of producing different discs for different regions of the world, both BD and HD-DVD now have the ability to create ONE disc to service the entire world. So you may want to include lossless streams of audio in English and Spanish, but to fit extra material, multiple commentaries, and soundtracks in French, Russian, Farsi, German, Portugese, etc, etc, you may have to put those in a lossy track.
Back to the original question--I load up a movie, and I'm staring at the audio selection screen. Which do I choose? As always, the answer is, "it depends"... on what your equipment is capable of, and how it's connected. But in general, the basic rule of thumb is, if you can, choose one of the LOSSLESS formats - Dolby TrueHD, DTS Master Audio, or PCM Uncompressed. Your next best choice is DD+ or DTS-HD.
Within these two categories, which one you choose is up to you. I have my own preference of one brand over the other, feeling that one gives more detail, but try it for yourself. Just like before you may have felt that DTS gave you better audio performance that Dolby Digital, now on the HD formats, you may feel that the Dolby version does better than DTS or vice versa.
Just a bit more on the "it depends", as I'm getting tired--if you have equipment specifically certified to decode Dolby TrueHD or DTS Master Audio, and you have the HDMI connection to support transmission from player to processor, (1.3 for processor decoding, 1.1/1.2/1.3 for player decoding) you can choose those. Even with Uncompressed PCM, you'll need to have a receiver that can receiver PCM over HDMI. Multichannel analog outputs after player decoding can also work.
If one of the lossless formats isn't available, or if your equipment isn't capable of decoding it, you'll have to choose one of the lossy formats. The good news is, even if you don't have equipment capable of, say, DD+, you can still choose it, and get great audio. It just won't be perfect lossless--your player will strip off the "extra channel packet", and give you the core DD or DD 6.1 EX signal, which can be sent over ANY digital connection or decoded and sent over multichannel analog.
Here's a great example of how HD audio can work to your benefit, even with compromises. I have a PS3, which has no multichannel analog outputs, only HDMI and optical for digital audio. I haven't upgraded my A/V processor, as HDMI audio processors are still extremely rare and limited in function, so I don't have HDMI audio with my processor, and am limited to digital optical for HD audio. As stated before, optical S/PDIF is not capable of carrying full HD audio streams. So I put in the U2: Rattle and Hum Blu-Ray disc into my PS3 and choose DTS-HD. The PS3 strips off the extra packet from the DTS-HD stream, and what it put out to my processor is full 1.5 Mbps DTS audio in 5.1 channels. It actually sounds BETTER on my system than my standard-def version of Rattle and Hum, even though it's just legacy DTS 5.1--studios stopped recording full bitrate DTS audio on standard-def DVD's years ago!
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