Multi-channel Audio for HD

[pchin]

Thanks so much Rodolfo for the detailed explanation. Took me to read a few times just to make sure all info is digested properly! Really helps me a lot!

[Richard]

Rodolfo,

Your input please on this Pioneer VSX-74Txvi

If I plug in a conventional dvd it automatically switches back to THX Ultra Select 2 which is correct. Then if I eject the conventional dvd and put in the HD-DVD (such as Serenity), the receiver once again automatically switches to the SACD mode (THX Musicmode)...The difference is dramatic...so it must be working.

I think I am getting confused by two terms here. Streaming and decoding.

What the above example cannot do is send any of the HD DVD HD Audio bitstreams to the receiver and have the receiver decode it into the individual digital channels and than A/D convert it for output. Right?

In the above example the user is getting the full benefit of HD DVD HD Audio as decoded by the source into the individual channels and delivered digitally to the receiver for D/A conversion. This is equal to using the 5.1 analog outputs and inputs for multi-channel; Basically you are choosing either analog or digital for this connection. Right?

If you choose digital then you likely will have access to speaker setup and bass management but if analog those features have to come from the source, hence the HDXA1 version which provides this. Or do both players provide the feature and the more expensive model is supposed to perform better when using that feature?



Thanks!

[Rodolfo]

Richard,

Messy isn' it?

The answer to your questions is yes.

A streamed signal expects the receiving device to decode and break out the channels for processing and amplification.

Decoding transforms the multi-channel stream into individual channels that can be handled by pre/amps sections for their function to amplify the line level audio to speaker level outputs. In that the pre also performs DSP, etc.

HDMI 1.3 allows streaming hi-bit audio out of Hidef players for external decoding, BUT WITHOUT THE AUDIO ADDITIONS OF THE MIX (unless the player has an additional encoder stage within it to add those audio mixes over the stream before the signal is out of the player).

HDMI 1.1 and 1.2 allows transporting the channels after they are converted (decoded) to PCM, the player does the decoding of the stream and adds the mixes to it, the pre/pro just receives the channels, no streams.

I can not recall seeing a spec for the expensier player claiming to improve bass management, etc. over the $499 model, I listed the differences between them as provided by Toshiba on the report, I believe that was not one of them (remote, open door, etc etc).

I would not spend $800 on a 1080i only HD DVD player when I can get a 1080p output from a Blu-ray player in a month for $200 more, unless Toshiba releases their second gen with 1080p outputs at a decent price and timing competitive with with the Blu-ray options.

There are many more coditions to check for the right selection of player and format, all that is part of my analysis on the dedicated section on the report, such as supported hi-bit codecs, you are facing one in your own LR with just 2CH True-HD decoding.

Best Regards,

Rodolfo La Maestra

[Richard]

Yes Rodolfo, quite messy...

Odd how the video is actually easier than the audio on this...

I think I am finally getting my head wrapped around this HD DVD HD audio format.

As for the HDXA1, from Shane...

On the audio side, the XA1 has four high performance DSP engines which allow not only for audio conversion, but also improved audio signal management (user selectable crossovers, delay management, and channel level management). Of course, if you're using a separate receiver or audio component to do this processing, there's no advantage.

I agree and am not going to spend more for that. Would be wiser to upgrade the receiver to HDMI digital multichannel input I would think and worry about the streams later down the line.

Thanks

[jkim]

Rodolfo,

As a relative new comer to HT, I have been scouring the web for useful information on hi-def DVD formats, audio codecs, HDMI specs, etc. You series on HDMI and multi-channel audio were extremely useful and I have read the multi-channel audio document no less than 5 times to make sure I grasped it all. I consider myself pretty adept at technology and this is confusing stuff, the average consumer is going to be lost for years. I digress.....

Few questions :

1) Part of the HD DVD vs Blu-Ray comparison has got to be supported audio codecs. As HD DVD approved Dolby Digital Plus and TrueHD as mandatory while Blu-Ray only approved legacy formats 5.1 DD and DTS. While many Blu-Ray DVDs may be produced with the optional hi-def audio formats, to me, this gives the clear advantage to HD DVD in the audio category. Am I putting this together correctly?

2) Are there a simple good, better, best title that can be applied to Dolby True-HD, Dolby Digital Plus, DTS-HD or is is not that simple?

3) HDMI 1.3. I know this is covered in your multi-channel audio document but I would like to confirm it. In terms of audio, the advantage of having HDMI 1.3 on the player and receiver is letting the receiver do the audio decoding. Will there be a significant audio advantage to this or is this a "nice to have" in terms of flexibility (vs running decoded signals into the reciever over HDMI 1.1? I am clear there is an advantage vs running decoded signals over 8 analog cables with many conversions between the disk and your ears).

One would argue (not for long) that 1) the hi-def DVD war will need to be over before purchasing either format and a compatible receiver or 2) buy a receiver that has the CLEAR capability to handle all audio codecs published today and video .

Thank you again for the articles.

Jason

[Rodolfo]

Jason,

I am glad you benefitted with the articles, that was exactly the purpose of my writting, but people has to read, most do not, you read it five times, ti which I say, Wow, and also, sorry, but the subject is a mess to start with.

Let me provide you with a response to each of the 3 questions you made:

A) An advantage of either format because in one format some codecs are mandated while the other are optional?, good point, it could be, but that would go away with HDMI 1.3 and A/V receivers/pre/pros with 1.3 inputs and decoders into them.

I would say the advantage could only be in the initial phase of the formats if a player manufacturer wanted to cut costs and did not include the optional codec you want, but if that approach goes for long one can always find a way out in the A/V receiver end, and still but the format for its overall value to you not for mandated codecs.

At this moment there are several features that were partially implemented in both formats, but they are gradually being incorporated in the 2nd generation models, and discs (combos).

B) DTS was always better than Dolby, starting by the higher bit rate, but now both with their hi-bit formats, they both claim they are bit-per-bit equal to the original (if you trust manufacturers).

Without having a facility to compare side by side both it would be unprofessional for me to comment either way, but my gut feeling is that DTS would sound better even on this hi-end level.

DD Plus was not designed to compete with the other two formats, so you can put DD Plus following the other 2.

C) HDMI 1.3 will soon have a pass-thru feature for hi-bit streams that would allow them to go directly from the disc to the player outputs (for external decoding), which means that no conversion, touching, processing of any kind would be applied to that signal. Any time you do any of that manipulation we all know that there is degradation of some kind.

Since the inception of redundant circuitry on any audio/video system there was and will be chips that perform better than others, in addition to the risk one runs when performing unnecessary conversions just for the signal to get from one piece of equipment to the other to find compatibility.

I believe that having the option of additional codecs on the receiver end is better than not having them, unless the extra cost of those surpasses the benefit and flexibility.

One has to remember that when DD was implemented many years ago it was a good idea to have the receiver as the nucleous of decoding because the many pieces of source equipment (DVD, HD cable tuner, OTA tuner, satelite tuner, etc) would not have to have it duplicated into them in addition to having to transport multi-analog cables rather than one with the undecoded DD stream.

That represented a savings in the overall system cost by having one decoder and simpler cables, but it better be a good one. Now Hi def DVD players (and games) are the only source of hi-bit codecs so it is not anymore an obvious saving from the circuitry duplicity point of view, and HDMI 1.3 could carry the stream and the PCM decoded version as well in one wire.

It also depends of the quality of the playing equipment and the receiving equipment, one would want the better quality equipment to perform decoding (unless to get to that good decoding a lot of previous signal manipulation would risk the signal quality upon arrival).

Best Regards,

Rodolfo La Maestra

[atgm8888]

Hello - thank you for a great article. I found it while looking to see if there was any sort of bidirectional audio capability in HDMI.

Is there anything in the standards that would support the data island equivalent of an audio input i.e. Line In, Microphone In etc.? Or is it, as it seems to be, strictly a system to supply high quality audio that goes in the same direction as the video?

Thanks in advance for your thoughts.

Andrew

[Rodolfo]

Thanks, I am glad the article was of use for you.

I am not sure what is your plan about using HDMI for your audio connection, but the connection was created for HD audio/video "secured" transport in one direction only.

However, the handshake activity between sender and receiver HDMI chips is constantly bi-directional for a) content protection and b) verification and adaptation of the sender to the receiver capabilities (i.e., a TV receiver HDMI chip telling to the sender's HDMI chip that it accepts only 2-channel from a 5.1 source).

Best Regards,

Rodolfo La Maestra