What's on HDTV?

A blog about video (and, occasionally, audio) in the HDTV age.

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Location: Catonsville, Maryland, United States

I'm Eric Stewart, a 66-year-old baby boomer, Catholic, single, no kids, two cats, retired as a computer analyst with the Social Security Administration (me, not the cats).

Friday, March 28, 2008

Blu-ray Audio Codecs Revisited

In Blu-ray Audio Codecs I gave a rundown on the various kinds of audio tracks that can show up on Blu-ray discs (BDs) and the various ways Blu-ray players can deal with them. Now I'd like to revisit the topic, because my original discussion left out at least one important point.

There are seven basic types of digital audio tracks that can appear on BDs:
  1. Linear PCM
  2. Dolby Digital 5.1
  3. Dolby Digital Plus
  4. Dolby TrueHD
  5. DTS 5.1
  6. DTS-HD High Resolution Audio
  7. DTS-HD Master Audio
Linear PCM (linear pulse code modulation) tracks on Blu-ray discs can have up to 7.1 channels of sound:

  • Three front channels: front left, front center, and front right
  • Four surrounds: left side, left back, right back, and right side
  • A low-frequency effects channel, the ".1," carrying just deep bass for a subwoofer
Many linear PCM tracks on BDs have 5.1 channels, not 7.1. In some cases, you may find 2.0-channel — or stereo — PCM tracks on certain BDs.

Linear PCM is recorded with no digital compression whatever. It offers uncompromised sound quality, at the expense of taking up a lot of space on the disc.

Linear PCM is specified as having so many bits per sample (the resolution), with so many samples per second (the sampling frequency). For example. the Blu-ray release of the movie Unbreakable has an English soundtrack with PCM 5.1 (48kHz/24-bit) surround sound. There are 48,000 samples per second of each of the six audio channels. Each sample contains 24 bits.

48kHz/16-bit sampling is also common. 96kHz at 16, 20, or 24 bits per sample is another sampling frequency that is permitted. It is also possible to sample each channel at a rate of 192kHz, using 16, 20, or 24 bits per sample, as long as the number of channels doesn't exceed six — i.e., for 5.1-channel audio.

All Blu-ray players are required to be able to pass linear PCM tracks through as is for use by an external receiver or a TV set. It can do this via an HDMI connection or via a digital optical output. All Blu-ray players must also be able to decode and downmix linear PCM tracks into two-channel stereo for output on analog audio connections.

Linear PCM is one of the three mandatory types of audio track which every BD must contain at least one of. The other two "mandatory" codecs are Dolby Digital 5.1 and DTS 5.1 — see below.


Dolby Digital 5.1 and DTS 5.1 are competing codecs for the lossy compression and decompression of up to 5.1 channels of audio. There are no left side and right side surround channels with either of these codecs. The compression is lossy, in that the decompressed audio stream is not absolutely identical to the original stream ... though the differences ideally can't be detected by the human ear.

DD 5.1 and DTS 5.1 have long been used on regular DVDs, with the former being present on virtually all DVD titles in the U.S. and the latter being used in addition to Dolby Digital (and/or linear PCM) on some DVD titles. For both, the maximum allowed bitrates (how many bits per second can appear in the encoded bitstream and need to be processed by the decoder) is low by today's standards. DD 5.1 has a maximum bitrate of just 640 kbps on BD. DTS 5.1 tops out at 1.524 Mbps.

If a Blu-ray disc lacks a linear PCM track, it must provide a DD 5.1 track and/or a DTS 5.1 track, since Blu-ray players are required to support only these three types of audio.


Dolby Digital Plus and DTS-HD High Resolution Audio are two competing formats for extending the audio fidelity of their respective predecessors, Dolby Digital 5.1 and DTS 5.1. Both allow up to 7.1 channels of audio on Blu-ray discs, including two side surround channels in addition to the customary rear surround channels, and both permit far higher bitrates going into the decoder, making for sound with much higher resolution. DD+ can use bitrates up to 4.736 Mbps on BD; DTS-HD HR, up to 6.0 Mbps.

However, both DD+ and DTS-HD HR remain lossy, so the output audio stream is not perfectly identical to the original input stream that is fed into the encoder when the disc is authored. Neither DD+ nor DTS-HD HR is required to be included as audio tracks on Blu-ray discs, nor are Blu-ray players required to be able to use these tracks if they do appear on a disc. DD+ and DTS-HD HR are "optional" codecs on Blu-ray.


Dolby TrueHD and DTS-HD Master Audio are competing codecs that extend Dolby Digital 5.1 and DTS 5.1, respectively, into the realm of lossless 7.1-channel audio compression on Blu-ray discs. Unlike DD+ and DTS-HD HR, these two, when decompressed, yield audio streams identical with the original streams fed into their compressor, bit for bit.

On BD, bitrates for TrueHD encoded bitstreams can be up to 18.64 Mbps. Master Audio encoded bitstreams can use up to a whopping 24.5 Mbps.

Blu-ray players are not required to support either Dolby TrueHD or DTS-HD Master Audio tracks, should they happen to appear on a BD. These two lossless codecs are strictly optional for players to be able to decode and for discs to include.


So there are four new codecs that can be used on Blu-ray discs as audio tracks, in addition to old standbys Dolby Digital and DTS (and in addition to linear PCM, which is not strictly speaking a "codec"). The four include Dolby Digital Plus and DTS-HD High Resolution Audio, both with lossy compression. They also include Dolby TrueHD and DTS-HD Master Audio, with lossless compression. For none of these four new codecs is a given Blu-ray player model required to be able to use them at all (!). The only compression-decompression schemes a player must support are Dolby Digital 5.1 and DTS 5.1.

In addition, always keep in mind, Blu-ray discs often include an uncompressed linear PCM track, which the player is required to support.


There are several ways in which a player can support any or all of the four optional advanced compression schemes (in addition to Dolby Digital, which the player has to support fully, and DTS, which the player also has to support fully). The four advanced codecs are:
  1. Dolby Digital Plus
  2. Dolby TrueHD
  3. DTS-HD High Resolution
  4. DTS-HD Master Audio
If a player supports any particular one of these codecs at all, the player can optionally:

  • decode it fully
  • decode just the "core" of it
  • pass through as a bitstream the entire audio track
  • pass through as a bitstream just the "core" portion of the audio track
A key concept here is the idea of a "core" bitstream. Taking as an example a Dolby TrueHD audio track, this track consists of two types of data. First, there is the information which would be present if it were only a Dolby Digital 5.1 track. The side surround channels are wholly absent. So is the data which increases the overall bitrate well beyond the 640 kbps allowed for DD 5.1.

This, accordingly, is the "core" bitstream for Dolby TrueHD. The remainder of the data in the input Dolby TrueHD bitstream is referred to as the "extension."

A Dolby Digital Plus track likewise has a "core" bitstream that is, in effect, equivalent to DD 5.1, along with a copious amount of "extension" data giving additional channels and/or higher resolution.

In like manner, DTS-HD High Resolution and Master Audio tracks have "core" bitstreams, equivalent to DTS 5.1 (not to Dolby Digital 5.1, which comes from DTS' rival company, Dolby Labs). These are, again, in both cases augmented by "extension" data.

(What about a DTS 5.1 track? It's already in effect just a "core" bitstream, with no "extension" data present. The player will decode all of it. If a player can pass it through as a bitstream at all, it passes through all of it.)


When a Blu-ray player decodes into linear PCM a digitally compressed audio track that includes both "core" and "extension" data, it may have the ability to decode both sources of data, the "core" data and the "extension" data, giving you all the audio information in the track.

Or, it may simply decode the "core" information and ignore the "extension," giving you the equivalent of just Dolby Digital 5.1 or DTS 5.1, depending on the "family" (Dolby or DTS) of the track on the disc.

Similarly, when a Blu-ray player is set up by the user to pass digitally compressed audio tracks through to an external receiver as an output bitstream — under the assumption that the receiver which receives it as input will be able to decode it — it may have the ability to pass through the entire audio track, including both the "core" and the "extension" information.

Or it may be limited to passing through only the "core" bitstream and ignoring the "extension" information. In the latter case, the receiver will act as if it is receiving just a Dolby Digital 5.1 bitstream or a DTS 5.1 bitstream, depending on the family of the track on the disc.


Unfortunately, it is not easy to find out how a particular Blu-ray player actually handles all these various types of audio streams.

If you are in the market for a player, you can easily search in vain for information about how the various models you are considering actually handle audio. Professional reviews, manufacturers' websites, and enthusiast forums often fail to specify, or specify incorrectly, how players react to the various kinds of audio.

If you actually buy a player, you might think its manual or user guide would clear up the matter once and for all, but, no: the literature is apt to add to rather than eliminate the confusion.

For example, the online manual for the Sony PlayStation 3, which is not just a game machine but also plays Blu-ray discs, has this to say:

BD / DVD Audio Output Format (HDMI)

Set the audio output format to use when playing a BD or DVD containing audio recorded in Dolby Digital or DTS format. This setting is used when an audio output device is connected to the system via an HDMI cable.



BitstreamSet to output audio with the original digital signal prioritized.
Linear PCMSet to output audio by converting the digital signal to Linear PCM format.

Hint

If [Bitstream] is selected, some portions of the audio content may not be output.


Huh?

That, sadly, is basically the only guidance you get. In truth, thanks to firmware updates that have happened since the manual was written, the PS3 can internally decode Dolby TrueHD fully, including the "extension" bitstreams. And it can, as of the latest firmware release (version 2.30), decode DTS-HD Master Audio as well.

The PS3 also passes through all four of the advanced codecs as bitstreams, but only in their "core" form, minus their "extensions." Additionally, it allows bitstreams of linear PCM tracks, Dolby Digital 5.1 tracks, and DTS 5.1 tracks — Blu-ray's three "mandatory" audio formats — to be passed through as is.

But you'd never know those things from Sony's PS3 online manual.

And it is often equally hard to find out what other Blu-ray players manufactured by Sony or ones made by the various other makers can do with the various kinds of audio tracks on BDs. Sigh.

Labels: ,

29 Comments:

Anonymous Anonymous said...

Thanks! That cleared up my understanding of bluray's audio codecs!

May 18, 2008 at 1:29 AM  
Anonymous Anonymous said...

Wow!!!!!!!!!!!!! What a great explanation!!!!!!! Thank you very much for clearing this all up for me; well written and easy to understand!!

Semper Fi

May 25, 2008 at 12:41 PM  
Anonymous Anonymous said...

The best explanation I've found so far!

July 19, 2008 at 12:32 AM  
Anonymous Anonymous said...

Wow, that was an amazing summary of everything I wanted to know. Thank you thank you thank you.

September 10, 2008 at 1:02 PM  
Anonymous Anonymous said...

Is it possible for an av receiver with True HD and Master Audio decoding to display True HD or Master Audio when the extension data is missing? Does 1.3 circuity eliminate this possibility? Can you have 1.3 at the BD player, 1.3 cable, and 1.3 on the av receiver and still wind up with just the"core"??

October 27, 2008 at 1:10 PM  
Blogger eric said...

Anonymous asked:

Is it possible for an av receiver with True HD and Master Audio decoding to display True HD or Master Audio when the extension data is missing? Does 1.3 circuity eliminate this possibility? Can you have 1.3 at the BD player, 1.3 cable, and 1.3 on the av receiver and still wind up with just the"core"??

My assumption is that an AV receiver that displays the TrueHD or Master Audio indicator for a given audio track would never do so unless the "extension" bitstream is actually present at the receiver.

On the Blu-ray player there may be a setting that would cause the player to output just the "core" bitstream for TrueHD/Master Audio input tracks. If that setting is used, I would imagine the receiver would not indicate TrueHD/Master Audio, since the "core" by itself is equivalent to Dolby Digital/DTS. I imagine any receiver would act as if it had no idea the audio track on the disk had an "extension" as well as a "core."

October 27, 2008 at 2:19 PM  
Anonymous Anonymous said...

Maybe I'm confused about what makes a track lossless. Is lossless defined simply by the fact that there are 2 extra channels in addition to 5.1? When you read, it sounds like each discrete channel has more or is better than the 5.1 in DD or DTS? Heres why I ask; Last night I went and looked at the back of about 20 Blu Ray movies. 8-10 of them said "Dolby TrueHD 5.1". I thought by definition when you see Dolby TrueHD it means there are 7.1 channels? Some discs had a comma or a colon after Dolby TrueHD and then said, English 5.1 or 5.1 PCM. do you think maybe these are typos? Also, some said DTS HD Master Audio and some said DTS HD Master Audio (7.1). My main question is; Dolby TrueHD 5.1??? Doesn't make sense??

Sincerely confused,
Jack

November 11, 2008 at 9:34 AM  
Blogger eric said...

Anonymous (Jack) asked:

Maybe I'm confused about what makes a track lossless. Is lossless defined simply by the fact that there are 2 extra channels in addition to 5.1? When you read, it sounds like each discrete channel has more or is better than the 5.1 in DD or DTS? Heres why I ask; Last night I went and looked at the back of about 20 Blu Ray movies. 8-10 of them said "Dolby TrueHD 5.1". I thought by definition when you see Dolby TrueHD it means there are 7.1 channels? Some discs had a comma or a colon after Dolby TrueHD and then said, English 5.1 or 5.1 PCM. do you think maybe these are typos? Also, some said DTS HD Master Audio and some said DTS HD Master Audio (7.1). My main question is; Dolby TrueHD 5.1??? Doesn't make sense??

There are a lot of questions there, Jack. First, "lossless" has nothing to do with the number of channels, whether 5.1 or 7.1. Rather, it has to do with whether the codec used to encode (digitally compress) the channels on the Blu-ray disc throws away information that cannot be recovered when the same codec works in reverse (in the Blu-ray player or in an external AV receiver) to decode (uncompress) the channels.

Dolby TrueHD and DTS-HD Master Audio are lossless because the decoding codec in the player or receiver can recover, bit for bit, every iota of information that the encoding version (of the same codec) compressed out. Whether there are 7.1 or 5.1 channels makes no difference. TrueHD and DTS MA tracks are always lossless.

Linear PCM is likewise always lossless, no matter how few or many channels there are. This is because PCM encoding does not compress the audio channels at all. You cannot get better sound fidelity than that!

But, of course, 5.1 or 7.1 linear PCM takes up more "bitspace" on the disc than 5.1 or 7.1 TrueHD, so TrueHD (or DTS-HD MA) is better in that regard.

DD or DTS encoding of up to 5.1 channels is always "lossy," no matter how few or many channels it has. The decoder recreates bitstreams, one per channel, that are not precisely the same as those that were cranked into the encoder. Ideally, the differences are undetectable to the ear.

Still, lossless compression (TrueHD or DTS-HD MA) beats DD or DTS, because in reality the bitrate constraints on DD or DTS make the differences between the input and output bitstreams subtly noticeable. You can supposedly hear how much better TrueHD is than old-fashioned DD, for example. And DTS-HD MA is aurally superior to DTS.

As for why TrueHD doesn't always have 7.1 channels: that's allowed(!). If the movie was produced with just 5.1 channels, for example, then the Blu-ray disc can have just 5.1 TrueHD. It's still lossless, but the extra two surround channels are absent.

If the disc says "Dolby TrueHD, English 5.1," then it means that on that disc there is an English-language audio track using 5.1 channels that have been encoded using TrueHD. If it also says "5.1 PCM," then presumably the same audio is provided in a separate linear PCM 5.1-channel track for those who do not have or do not choose to use a TrueHD decoder.

"DTS-HD Master Audio" on the disc cover means just that, without reference to how many channels there are — you can guess that there are actually 5.1 channels, since if there were 7.1, the disc would probably say so: "DTS HD Master Audio (7.1)".

In short, Jack, it is not the case that Dolby Digital TrueHD or DTS-HD Master Audio imply 7.1 channels. Rather, those expressions imply strictly lossless encoding/decoding of however many channels there are.

November 11, 2008 at 11:54 AM  
Anonymous Anonymous said...

Well put. I believe I finally get it now. I almost regeret trying to do a little homework before upgrading our entertainment. You dang near have to be some sort of engineer to figure out what you are buying and what you are getting. As much as the sound formats interest me, I'll have to remember that audio tracks can't be the primary reason to select a movie. Can you believe that the rest of my family doesn't care what audio tracks are on the disc? They think the movie itself is most important. Imagine that!! Ha Ha! Last question; if I get a disc with a 5.1 lossless track, will my 7.1 receiver create 2 channels to fill the other 2 surrounds? Seems like receiver specs sometimes use the term "decoder" when actually it's creating (matrixing) extra channels.

Regards,
Jack

November 11, 2008 at 1:14 PM  
Blogger eric said...

Anonymous (Jack):

Glad I could help.

You asked:

"... if I get a disc with a 5.1 lossless track, will my 7.1 receiver create 2 channels to fill the other 2 surrounds? Seems like receiver specs sometimes use the term "decoder" when actually it's creating (matrixing) extra channels."

It's possible that your receiver might fill in the extra two surround channels. What make and model receiver do you have?

November 12, 2008 at 5:45 PM  
Anonymous Anonymous said...

Seriously considering the Yamaha RX-V663. Originally, I was not looking for the receiver to decode the lossless formats. I undestood that if the BD player internally decoded, then the receiver just needed to amplify the LPCM (some HDMI equipped receivers ignore the audio potion and use only the video for switching purposes, I guess). The problem with this setup(based on your article) is that I would have no way to verify what the BD player was sending. The receiver would display "Multi-channel input". My conclusion is to have the receiver do the decode if I want to be absolutely sure that I'm hearing everything that there is to hear. I've read several reviews on the Panasonic players and evidently they can bitstream the core and extension since the reviewers are saying the receivers are showing it on the display.

Jack

November 13, 2008 at 1:39 PM  
Blogger eric said...

Jack,

You said:

"Seriously considering the Yamaha RX-V663. Originally, I was not looking for the receiver to decode the lossless formats. I undestood that if the BD player internally decoded, then the receiver just needed to amplify the LPCM (some HDMI equipped receivers ignore the audio potion and use only the video for switching purposes, I guess). The problem with this setup(based on your article) is that I would have no way to verify what the BD player was sending. The receiver would display "Multi-channel input". My conclusion is to have the receiver do the decode if I want to be absolutely sure that I'm hearing everything that there is to hear. I've read several reviews on the Panasonic players and evidently they can bitstream the core and extension since the reviewers are saying the receivers are showing it on the display."

You are in an increasingly common position of wanting to be sure what you are actually hearing with Blu-ray discs. (BTW, what Blu-ray player do you have/are you contemplating?)

I've just looked at some online reviews of the Yamaha RX-V663 AV receiver, and it appears what you would be getting getting for its midrange price of around $500 "is the cheapest model in the RX-V ... series of Yamaha receivers to support both video upconversion to HDMI and HD audio decoding of Dolby TrueHD and dts HD-MA."

That sounds pretty good. Yet I'd have to wonder: If your (current or anticipated) Blu-ray player decodes TrueHD 7.1 core and extension bitstreams to linear PCM 7.1 and outputs the result over HDMI version 1.3, do you really need to pay for another TrueHD decoder in the receiver? (The same question goes for DTS-HD Master Audio decoding.)

I would think than any receiver that can confirm on its front display (or, better yet, on the TV screen) that it is receiving LPCM 7.1 from the player would put all your doubts to rest.

I know there are some people who doubt that onboard decoding of the new lossless audio codecs by a Blu-ray player gives you results identical to the decoding a receiver can do, but I for one believe that's a myth.

I don't yet have a Blu-ray player --- that's next on my list of toys to buy --- and neither do I have a receiver of the advanced type you're looking at. So I can't advise you based on my own hands-on experience. Still, it seems to me that if money is as tight for you as it is for me, you may want to think about avoiding the redundancy of buying two decoders for each of the two types of lossless audio compression on Blu-ray discs!

November 13, 2008 at 2:45 PM  
Anonymous Anonymous said...

I've been looking a BD players and new A/V receiver on and off for almost a year. At first, this is what I found; it costs around $100 or so more for a BD player to decode the lossless formats as opposed to $300-$400 more for an A/V receiver that could do it. Originally, I was looking to buy a 5.1 A/V receiver. To this day, I can't find a 5.1 A/V receiver with the lossless decoders. Since my wife has decided to redesign the use of our living room, I figured 7.1 would fill a 25x15 area better. It just so happens that the few mid range priced receivers I've been looking at happen to have the TrueHD & DTS MA decoders(Onkyo 606 was the other one). If user reviews are correct, the Panasonic DMP-BD30K ($250) cannot decode (lossless) and send LPCM, but can bitstream all data successfully. The Panasonic DMP-BD35 ($300) according to manufacturer website can do both. Now,there's only a $50 difference and the BD35 has a few extra features that I may or may not need. My current plan is to buy the BD30, save $50, and enjoy lossless sound!!!

November 14, 2008 at 1:51 PM  
Blogger eric said...

Jack,

You said:

"I've been looking a BD players and new A/V receiver on and off for almost a year. At first, this is what I found; it costs around $100 or so more for a BD player to decode the lossless formats as opposed to $300-$400 more for an A/V receiver that could do it. Originally, I was looking to buy a 5.1 A/V receiver. To this day, I can't find a 5.1 A/V receiver with the lossless decoders. Since my wife has decided to redesign the use of our living room, I figured 7.1 would fill a 25x15 area better. It just so happens that the few mid range priced receivers I've been looking at happen to have the TrueHD & DTS MA decoders(Onkyo 606 was the other one). If user reviews are correct, the Panasonic DMP-BD30K ($250) cannot decode (lossless) and send LPCM, but can bitstream all data successfully. The Panasonic DMP-BD35 ($300) according to manufacturer website can do both. Now,there's only a $50 difference and the BD35 has a few extra features that I may or may not need. My current plan is to buy the BD30, save $50, and enjoy lossless sound!!!"

I just found out about the new Panasonic DMP-BD35 model of Blu-ray player, and after reading the glowing review of it on CNET ("the best value in standalone Blu-ray players, with excellent image quality, a comprehensive feature set, and a price that's significantly lower than the [Sony PlayStation 3") I've penciled it in as my first Blu-ray player.

What we have been discussing in this series of comments concerns a key issue in the Blu-ray world: decode lossless codecs in the player, or in the receiver ... or in both of these, so that you can take advantage of the redundancy when those inevitable is-this-really-working-right? questions pop up.

I think if I were you and were set on getting a mid-priced 7.1-channel receiver that decodes the new lossless audio codecs onboard — and that's great if you can afford it — I'd also spend the extra $50 for the BD35 player, over the BD30.

Why? Well, it gives you diagnostic redundancy for lossless audio codec playback, it gives you an Ethernet jack for those all-too-common firmware upgrades, and it gives you access to BD-Live Profile 2.0 interactive content. It's also said to be faster at loading discs and more responsive overall than anything except the PS3. And it's a 2008 model, not a 2007, which means superior performance.

November 15, 2008 at 11:01 AM  
Anonymous Anonymous said...

Hello Eric,

I now know what is meant by "Analysis leads to Paralysis". BD35K now down to $250. Apparently, the Yamaha 663 cannot decode and apply the matrix overlay for the 5.1 to 7.1. But, it can do it when receiving PCM. I guess this means the decoders in the A/V are useless, unless I have a Blu Ray disc with 7.1 (good luck, there are only a few)and set to bitstream. Otherwise, the rear surrounds will be silent. I'm back where I started. Decode in the player. HDMI 1.3 not necessary in the circuitry or the cable using this method.(assuming I understand the capabilities of a 1.1 HDMI cable). If 5.1 PCM is matrixed to 7.1, can we conclude that these matrixed channels are also lossless since the data was taken from a lossless track?

Jack

December 23, 2008 at 5:33 PM  
Blogger eric said...

Jack,

I now know what is meant by "Analysis leads to Paralysis".

Hee, hee!

BD35K now down to $250.

Good. But see the posts in my blog about how you can get a Sony PlayStation 3 for $250 with a $150 rebate for applying for a Sony PlayStation credit card. I just did this myself, and I'm very happy with the PS3. But I don't have an AV receiver yet, and the wonders of 7.1 sound are just a theoretical thing right now for me.

Apparently, the Yamaha 663 cannot decode and apply the matrix overlay for the 5.1 to 7.1. But, it can do it when receiving PCM.

For kibitzers: I think Jack means the Yamaha RX-V663 receiver apparently can't take Dolby TrueHD 5.1 or DTS-HD Master Audio 5.1 "bitstream" input from the Blu-ray player and derive the extra two surround channels, for 7.1-channel sound. But it can do this for linear PCM 5.1 input.

I guess this means the decoders in the A/V are useless, unless I have a Blu Ray disc with 7.1 (good luck, there are only a few) and set to bitstream. Otherwise, the rear surrounds will be silent.

They're apparently useless with the Yamaha RX-V663 receiver you're looking at, if you need the receiver to derive 7.1-channel audio from 5.1 with the new lossless codecs. I haven't researched other receivers. Are there some (presumably more expensive) ones that do derive 7.1 from 5.1?

I'm back where I started. Decode in the player. HDMI 1.3 not necessary in the circuitry or the cable using this method.(assuming I understand the capabilities of a 1.1 HDMI cable).

I personally believe decoding to LPCM in the player and deriving the extra two surround channels, if desired, is a fine choice.

I would encourage you to stick to HDMI 1.3 anyway, in any new devices you buy. Why not? It offers several advantages.

However, I am skeptical about whether you have to shell out for expensive "HDMI 1.3" cables, specifically. Admittedly, I do not have an elaborate audio setup with an HDMI cable from the player to the receiver and another from the receiver to the TV. I hooked my PS3 to my Samsung HDTV (both of which, I assume, use HDMI 1.3) using an inexpensive non-brand-name HDMI cable that I bought online, and it works fine! I used the same type of HDMI cables for connecting my Apple TV and my TiVo HD to the Samsung TV. All work fine.

On the other hand, until the most recent update of the Apple TV software, my Apple TV was flaky, and the online scuttlebutt had it that the problems I and many other users were having were HDMI-related. Many users tried changing to really expensive HDMI cables, but it didn't help. What helped was getting HDMI working right in the device itself.

I would recommend you or anybody else start with the inexpensive cable(s) and only move up to the pricey ones if absolutely necessary.

If 5.1 PCM is matrixed to 7.1, can we conclude that these matrixed channels are also lossless since the data was taken from a lossless track?

No, that would violate the basic definition of "lossless." The extra two channels don't exist in the input to the decoder, so there's nothing to compare the result of the decoding to, to determine whether it is lossless or not.

Cheers,
Eric

December 23, 2008 at 8:31 PM  
Blogger KenJr said...

When a disc notes that it has PCM 5.1 audio, that could represent a pretty broad range of sonic quality. I'd be very happy if a purchase featured 24 bit/196 kHz (like that found on the Divertimenti blu-ray audio only disc) but I'd be pretty disappointed if it turned out to be 16 bit 44.1 kHz. I'm trying to find out which opera/classical music sources will feature the best sound for my audio system.

For instance, I'm trying to find out the OpusArte bit and sampling rates for its pcm 5.1 blu-ray discs (e.g. The Magic Flute). They don't state this information. I've searched everywhere for this information to no avail. Do you know any way of getting this information? For that matter, do you know what OpusArte's specs are?

December 24, 2008 at 1:45 PM  
Blogger eric said...

KenJr,

It looks to me as if the Opus Arte Blu-ray disc of Mozart's Die Zauberflote has PCM 5.1 audio, all right, but there's no indication as to how high the sample size in bits and sampling rate are.

I suggest you rent the title from Netflix and try it on your equipment. I myself don't have an up-to-date AV receiver, but I imagine your receiver can tell you what the vital statistics of the audio stream are, correct? If you like what you see and hear, then you could buy the disc.

I agree with you. This information should be easily available, especially with titles intended for connoisseurs.

I sometimes take the position that if the audio resolution figures were prepossessing — e.g., 24 bit/196 kHz — the company would advertise them prominently. If they are not so advertised, they are probably of lower quality.

December 24, 2008 at 2:34 PM  
Anonymous Anonymous said...

Dear Eric

I won't add further congratulations, even if you desserve them considering the hard task you did in this Blu-ray Audio codecs description and explanation. Great job.

I have just one question. I would like to draw your attention on the maximum bit rate that you have mentioned for the DTS Digital Surround coding. Your wrote 1.524 Mbps. Just as a reminder for DVD this maximum bit rate was set to 1.536 Mbps but usually we find on a DVD 768 kbps. But as far as I could understand now the DTS Digital Surround is the fondation of the DTS HD architecture to anaible scalability and it starts as a core stream at 1.509 Mbps (5.1) and it is present in all other advanced coding (HD High Resolution and HD Master Audio).

Please can you clarify this point and tell me if my impression was wrong.

With kind regards and please keep going. We need people like you to help understanding all these new things.

Jayjay

February 19, 2009 at 1:41 AM  
Blogger eric said...

Jayjay,

Thanks for your praise!

As for your question, I must confess I don't quite understand what you are trying to say. So I'll just try to point you to a source that might answer your concerns.

You can get all the official information about DTS-HD by reading the DTS-HD White Paper.

According to this paper, DTS-HD in its full-fledged form — DTS-HD Master Audio — can deliver "a bit-for-bit recreation of the original master recording using variable bit rate encoding as high as 24.5 Mbps."

"An existing A/V receiver or system with DTS decoding can play back DTS-HD Master Audio at 1.5 Mbps, nearly twice the data rate of other formats," it says. I do not actually know whether this "core" decoding of what is effectively DTS 5.1 material (i.e., ignoring the DTS-HD "extension") has a bit rate that is more precisely 1.509 Mbps, or 1.536 Mbps. This source says the latter, while the paper mentioned above says the former. I am not sure the disagreement over the extra decimal places makes any practical difference. Would you comment further on the subject if you disagree?

Thanks for your input!

February 19, 2009 at 9:23 AM  
Anonymous Anonymous said...

This is a great site..thanks for all the useful info. I was wondering i you could answer a question for me.
I dont have a receiver with HDMI. SOmeone suggested i get a blue ray player that decodes the uncompressed sound and make it so that it can be played through a receiver without hdmi. ( i think the store said sony makes one) if thats possible...will it still be the same quality sound as if it was played through HDMI?

April 6, 2009 at 8:17 PM  
Blogger eric said...

Anonymous asked:

I dont have a receiver with HDMI. SOmeone suggested i get a blue ray player that decodes the uncompressed sound and make it so that it can be played through a receiver without hdmi. ( i think the store said sony makes one) if thats possible...will it still be the same quality sound as if it was played through HDMI?

There are two separate issues here.

One is the ability of any particular model of Blu-ray player that you might consider buying to decode the various audio codecs internally without discarding any of the information. You want to make sure that the player decodes both the "core" and the "extension" information for 7.1-channel DTS-HD Master Audio and for 7.1-channel Dolby TrueHD audio.

The second is the ability of the Blu-ray player to provide all the channels of the audio to the receiver, while not using HDMI. For 7.1-channel audio, this requires that the player and receiver both have connections to pass 7 channels of analog audio (plus the .1-channel Low Frequency Effects or bass information for a subwoofer, which requires an 8th analog connection).

Putting both considerations together, you want to be sure the player decodes all 8 of the available channels for the two highest-resolution audio codecs and passes all 8 of them along to the receiver in the form of multi-channel analog connections.

If your current receiver can't provide the requisite 8 multi-channel analog audio connections, your best bet is to bite the bullet and buy a new receiver that uses HDMI. Then get your best deal on a Blu-ray player that gives you the option to (a) decode the codecs I just mentioned into 7.1-channel Linear PCM and outputs that form of audio on HDMI, or (b) pass these and the other codecs I mentioned in my original article as is on HDMI for decoding in the receiver itself.

Finally, a word of caution: don't be fooled into thinking that you can get "all the audio" if you pass the audio from the player to the receiver along what are now old-fashioned "optical digital" and/or "coaxial digital" audio connections. These require that the audio of the best codecs (the ones I just mentioned) be pared down to shoehorn it into the lower-than-HDMI bandwidth of these now-obsolete connections.

April 7, 2009 at 9:11 AM  
Blogger mandy said...

This comment has been removed by the author.

January 9, 2010 at 2:44 AM  
Blogger mandy said...

Have a problem here with audio codec's and yamaha RX-V663

while playing HD sound signals (via LG BD370 bluray player)when i hit menu---->signal info, on RX-V663, there is no info about bitrate , tried several discs with TrueHD and MA with no luck (but it does give bit rate info with standard DD & DTS signals)

I have set my bluray player to output sound as both bitstream and MULTIPCM/LPCM but still on info about bitrate.

ERIC sir plz help out, what could be the reason?

January 9, 2010 at 2:57 AM  
Blogger eric said...

Mandy said:

Have a problem here with audio codec's and yamaha RX-V663

while playing HD sound signals (via LG BD370 bluray player)when i hit menu---->signal info, on RX-V663, there is no info about bitrate , tried several discs with TrueHD and MA with no luck (but it does give bit rate info with standard DD & DTS signals)

I have set my bluray player to output sound as both bitstream and MULTIPCM/LPCM but still on info about bitrate.


Mandy,

See the forum post

http://www.avsforum.com/avs-vb/showthread.php?p=17885604

and its following posts.

If you happen in fact to be the author of that post (shareknow), then I'm wondering why you weren't satisfied by the responses.

If you are not shareknow, you'll probably find out what you need to know.

Basically, the idea seems to be that (according to vladd) "Bitrate doesn't show when playing HD or PCM audio formats [on the Yamaha RX-V663]. It doesn't do it on the [RX-V]863 either (same firmware). It only shows for legacy bitstreamed formats (DTS/AC-3)."

In other words, blame the firmware Yamaha provides for that receiver.

Another responder said that "When my PS3 plays DTS-HD Master Audio it will not send it to the receiver as a bitstream, only converted to PCM. The signal info shows 48 kHz 5.1 channel PCM and does not show a bitrate. My PS3 shows the original bitrate varying, but typically around 4.5 Mbps. This is for Battlestar Galactica: The Plan."

I imagine by "my PS3 shows" he means that the Sony PlayStation 3 can add "Display" information, showing bitrate and other parameters, to the video picture that is forwarded to the TV screen.

Whatever the instantaneous bitrate shown in the PS3's on-screen display is also the bitrate that the Yamaha receiver would "see" if, say, I had my PS3 hooked to that model of receiver. Your LG BD370 Blu-ray player apparently can't put a similar display on the TV screen, but you have every right to assume that your Yamaha RX-V663 is "seeing" the same instantaneous bitrates as my hypothetical one would see.

Also, keep in mind what another responder in the thread mentioned above said: If you are playing a TrueHD soundtrack on your player, then (because TrueHD is lossless) you cannot be getting anything other than the best possible sound quality that the Blu-ray disc is capable of providing. It doesn't really matter whether you are having your player decode the soundtrack and send linear PCM to your receiver, or you are sending the TrueHD bitstream to the receiver as-is and having the receiver do the decoding.

The exact same thing is true if you are playing a PCM soundtrack on Blu-ray, which is likewise lossless -- it's not even digitally compressed in the first place!

So, Mandy, you can stop worrying and just sit back and enjoy ...

Cheers,
Eric

January 10, 2010 at 1:09 PM  
Blogger mandy said...

Thanks Eric Sir,

shareknow and mandy are the same:-).

what i wanted to to be clear is, whether this has to do with only RX-V663 or all other receivers from different manufacturers.

As the thread mentioned here is only concerned with Yamaha RX-V663 and 863 only.

SO NOW ITS SAFE TO ASSUME THAT "NO RECIEVER WILL SHOW BITRATE INFO FOR LOSSLESS HD SOUND CODEC'S"

AM I RIGHT?
thanks

January 11, 2010 at 4:59 AM  
Blogger eric said...

Mandy (shareknow),

You wondered:

what i wanted to to be clear is, whether this has to do with only RX-V663 or all other receivers from different manufacturers.

As the thread mentioned here is only concerned with Yamaha RX-V663 and 863 only.

SO NOW ITS SAFE TO ASSUME THAT "NO RECIEVER WILL SHOW BITRATE INFO FOR LOSSLESS HD SOUND CODEC'S"

AM I RIGHT?


Actually, Mandy, I believe the Yamaha RX-V663 and RX-V863 receivers may be unusual in not showing bitrate info for lossless audio codecs, and that various other receivers (even others from Yamaha) may show this info.

I believe Yamaha's decision to not show that info on these receivers may have to do with the chipsets they chose for the receivers. Receivers from different makers (or even from different model lines of a given maker) can use different chips for different decoding functions, and the ones that the RX-V663 and RX-V863 use for decoding non-lossless audio obviously report bitrate. The lossless decoders don't.

That, in turn, may be because with lossless codecs, decoder-encountered bitrates are pretty much irrelevant. As output from the decoder you're sure of getting every last bit of data that existed in the original, uncompressed PCM streams that were losslessly encoded for (say) TrueHD at the time that the Blu-ray disc was mastered. What more could you want? The actual bitrates of the TrueHD-encoded intermediate stream make no difference whatsoever. That's what "lossless compression" means!

Best regards,
Eric

January 11, 2010 at 9:19 AM  
Blogger mandy said...

hello Eric sir,

There has been a strange occurrence:

Earlier when i was mistakenly using 1.2a HDMI (now its HDMI 1.3C) to route signal from Player to Reciever, the Truehd light did lit up on my reciever and showed the same signal info.

I am confused here, that means 1.2a can also carry HD signals?

But HDMI specs for 1.2a don't agree.

Thanks

January 16, 2010 at 9:10 AM  
Blogger eric said...

Mandy,

You asked:

There has been a strange occurrence:

Earlier when i was mistakenly using 1.2a HDMI (now its HDMI 1.3C) to route signal from Player to Reciever, the Truehd light did lit up on my reciever and showed the same signal info.

I am confused here, that means 1.2a can also carry HD signals?

But HDMI specs for 1.2a don't agree.


I take it you are wondering whether the older HDMI standard, version 1.2a, can carry Dolby TrueHD audio. According to this Wikipedia topic, the answer is no. Only HDMI version 1.3 (and later versions) optionally support output of Dolby TrueHD and DTS-HD Master Audio streams for external decoding by AV receivers.

However, I don't quite know what you mean by "mistakenly using 1.2a HDMI ... to route signal from Player to Reciever." The HDMI version you are using depends mainly on the devices at either end of the HDMI cable. You have a Yamaha RX-V663 receiver and a LG BD370 Blu-ray player, both of which support Dolby TrueHD. That means both support HDMI version 1.3 (or later).

Perhaps you are referring to the HDMI cable you were using. It is true that you nominally need a "Category 2-certified cable" (see this Wikipedia topic) for routing HDMI 1.3 audio, but the topic continues, "Many HDMI cables under 5 meters of length that were made before the HDMI 1.3 specification can work as Category 2 cables, but only Category 2-tested cables are guaranteed to work." My conclusion is that if your original cable was under 5 meters in length, probably the switch to a newer cable made no difference.

If your original cable was unable to route TrueHD for some reason, you would not have seen the TrueHD indicator light up on your receiver!

Regards,
Eric

January 16, 2010 at 10:00 AM  

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