[REQUEST] Multi-channel decoding of audio codecs over HDMI

[peterjcat]

Most of you will know that the PCH is currently only licensed to decode AC3, DTS, WMA and AAC into two channels (stereo), which it can then send out as PCM over the analog, optical or HDMI outputs. Of course, analog and current standards of optical audio can only carry two channels of PCM audio.

However, HDMI can carry up to 7.1 channels of uncompressed PCM audio. Further, the Sigma chipset, which is designed to be used in modern Blu-ray players, may well have the technical ability to decode at least 5.1 channels of all the Dolby and DTS codecs up to TrueHD and DTS-HD MA. Finally, the increased processing power of the C-200 almost certainly has the ability to decode at least 5.1 channels of AAC and WMA -- as we can see from its successful decoding of 5.1-channel FLAC in the current beta firmware.

So the limiting factor here isn't a technical issue but a licensing one. Licences for extra channels and codecs cost extra. How much extra isn't publicly available, but PCH would know. Some really cheap Blu-ray players (eg LG BD 370, $150 from Amazon) now decode everything up to 7.1-channel DTS-HD MA to PCM, so I'm assuming the cost isn't a staggering one, though of course all costs contribute.

At this stage you might ask what is the point of decoding in the player when you've got a perfectly good AV receiver that will take a bitstream from the C200 and do the decoding itself? There are two answers depending on the codec:

1. For AAC and WMA, most modern HDMI-capable receivers still don't decode these. So the C200 decoding these to PCM to send out over HDMI would provide a real benefit for those people who have multichannel AAC or WMA audio in their movies.

2. For the Dolby and DTS varieties, there are still quite a few modern HDMI-capable receivers, particularly in the Home Theatre In A Box range, plus older HDMI receivers, that don't decode at least the HD audio codecs, but can receive a full multichannel PCM stream via HDMI. BUT for most setups there is no benefit in decoding in the C200 instead of the receiver, UNTIL YOU GET TO BLU-RAY.

Blu-ray has three main advantages over conventional DVD: improved picture, improved sound, and improved viewing experience combining special features, picture-in-picture commentary, in-movie navigation etc. For this third thing, you need to be able to decode the primary and secondary audio tracks WITHIN the player so you can mix them together, eg you're watching the main movie, the thing pops up to tell you that some dude wants to tell you about how the special effect was done, you press the button, the main audio gets softer and the audio of the dude talking comes in over the top of it, so you can still keep track of what's going in the movie AND hear what the dude is saying.

More and more studios are getting more and more creative about the secondary audio and video tracks they're including in movies, and what started out as pretty lame is now, I believe, pretty cool. You probably wouldn't use any of it when watching the movie for the first time, but if it's a movie you love and want to watch it again, it's actually pretty interesting to have these special features on. The C200 has the grunt to make them all fit together seamlessly on the screen, but it lacks the licensing to make them actually work because you can't hear what's going on.

We all know that the C200 is the best media player in the world; unfortunately, due to the current restrictions it seems doomed to being the worst Blu-ray player in the world, as every other player is more capable of handling Blu-ray audio in the way that it is intended. Of course, many people don't care at all about special features, and often they're terrible, but wouldn't it be nice to have a player that could do them properly, just in case you or your kids or guests suddenly decided to find out how they did that scene or whatever?

It's my belief that the marketing line still being used for the C200, "Add a Blu-ray drive to turn your Popcorn Hour C-200 into a full-featured Blu-ray player" is a bit misleading, as without properly handling special features through multichannel audio mixdown the C200 can only ever be an almost-full-featured but never full-featured Blu-ray player.

So I wonder who else feels their lives would be improved by adding multichannel decoding for (1) AAC and WMA, or (2) DTS and Dolby Digital, including DTS-HD, DD+ and TrueHD?

There would probably be a cost involved, and the DTS experience with the A-100/A-110 seemed to suggest that PCH couldn't add "bolt-on" licences for existing users but would be charged on the basis on all the units ever sold. But I wonder whether the C200 might be classified differently, more like a PC than anything else (you can choose between stereo or multichannel versions of PowerDVD etc). Or I wonder whether PCH might slightly increase the price of all FUTURE C200s and give all current owners the upgrade for free -- as a reward for early adoption, perhaps. I know it's far-fetched but they can't have sold that many yet.

Or of course they could just release a new model, a C-210 or whatever, that has full multichannel audio decoding capability, like every real Blu-ray player out there.

Either way, add a comment if you'd be interested, so PCH can gauge whether it might be a worthwhile thing for them to bring to market. I can't help but think that having full-blown Blu-ray support, rather than the somewhat half-baked support they have now, would be a valuable thing. But then I'm really into my Blu-rays.

[michaelr64]

Can you tell me what actually happens when you try to play a BR-disc in such a way on the C200 ?
Will it do nothing, play only audi stream etc...
Could you put in some links to threads which mention this problem ?

Is this linked to or equal to http://www.networkedmediatank.com/showth...?tid=28305 no. 5 ?

Is there a difference when playing BR-iso/BR-folder/BR-disc ?

[peterjcat]

It's not a bug, it's an inherent limitation in the decoding licences PCH has chosen to purchase from Dolby/DTS for the C-200.

The result will be, even when all the bugs are fixed and the C-200 is working perfectly:

1. With DTS and AC3 set to Analog/PCM, primary audio and secondary audio will be mixed together, but only output in stereo.
2. With DTS and AC3 set to Digital/RAW, primary audio will play in multichannel, and secondary audio will never play.

At the moment, mixdown isn't working at all, so whatever option you choose you'll only get primary audio and secondary audio will do nothing. There are other bugs as well, like the ones you list, eg primary AC3 audio sometimes isn't selectable when there's an HD audio track present; and bitstreaming isn't available when there's a secondary audio track.

But the fundamental problem will continue even when all the bugs are fixed, UNTIL PCH decide to purchase multichannel decoding licences from Dolby and DTS. Only then will the C-200 behave like a Blu-ray player is supposed to.

And no, there's no difference between playing from disc, from folder or from ISO. Like I say, it's not a bug, PCH simply hasn't purchased the licences they should have if they wanted to sell a full-featured Blu-ray player.

[michaelr64]

I got the part about it not being a bug already, i just wanted a bit better explained what happens now when doing this.

I absolutely agree with you that i payed top dollar for a unit which can not handle this at present regardless of bugs.

Has Syabas or Werner for that matter responded in acknowledging this situation as working as designed or the result of say a buggy Sigma sdk ?
In the latter case we might still expect this feature later on.
In the former this is not acceptable really.

I couldn't find a reference to a post explaining Syabas point-of-view on this in your story.
This would clarify matters a lot.

@Werner: can you comment on this ?

[Oddwunn]

How about FLAC?

These days a great many of us rip our Blu-ray discs and then remux the full bitrate video with a multichannel FLAC audio track. Using madshi's Eac3to it is a simple matter to demux the lossless track (DTS-MA, TrueHD, or LPCM) and then re-encode it using FLAC. If the C-200 had the ability to decode multichannel FLAC from within an .MKV container then no royalties would have to be paid at all, and the C-200 would be able to provide lossless multichannel audio.

What do you think?

[Willem53]

OK... lets assume WMAPro and AAC are multichannel PCM on the HDMI it would make no difference for the majority of users who just do stereo on their TV..right..?
I like the Idea very much but if Microsoft and Apple demand to much of a license fee per unit we will need to wait for the majority to be on Home cinema audio systems and WMA and AAC to make it to the living room as popular audio formats... only place I see them now being popular is the mobile audio scene...... in stereo...

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(11-16-2009 05:05 AM)Oddwunn Wrote:  How about FLAC?

These days a great many of us rip our Blu-ray discs and then remux the full bitrate video with a multichannel FLAC audio track. Using madshi's Eac3to it is a simple matter to demux the lossless track (DTS-MA, TrueHD, or LPCM) and then re-encode it using FLAC. If the C-200 had the ability to decode multichannel FLAC from within an .MKV container then no royalties would have to be paid at all, and the C-200 would be able to provide lossless multichannel audio.

What do you think?

Multi Channel FLAC on the C-200 ..... who knows... maybe the little CPU could handle it... maybe not.... old discussion, but hey are working on it...

[peterjcat]

(11-15-2009 12:03 PM)michaelr64 Wrote:  Has Syabas or Werner for that matter responded in acknowledging this situation as working as designed or the result of say a buggy Sigma sdk ?
In the latter case we might still expect this feature later on.
In the former this is not acceptable really.

I couldn't find a reference to a post explaining Syabas point-of-view on this in your story.

Well wouldn't you know it, I can't find anything specifically from Syabas saying they don't have multichannel Dolby/DTS licences for the C-200, but that is certainly the received wisdom. No previous NMT has been able to decode anything to multichannel PCM, only stereo, which hasn't been so much of a problem because no previous NMT has been able to deal with Blu-ray special features anyway. And from the first discussions about the C200 it has been stated/assumed by moderators etc that there'll be no multichannel decoding, eg this from chris57:

Quote:The decoding that the C200 and indeed the A110 can do is stereo only of the DTS core. DTS decoding costs per channel and will not be available for anything other than stereo from DTS.

As with many issues there's been nothing official from Syabas/PCH so I'd also be very keen to have the position confirmed or clarified by Werner. As far as I know there has been no mention of multichannel decoding support on the roadmap, though other issues such as no bitstreamed audio when PiP is present, no AC3 audio when an HD track is present, etc, come under the umbrella of "new Sigma SDK issues".

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(11-16-2009 05:05 AM)Oddwunn Wrote:  How about FLAC?

Well FLAC is great, and Willem says it's being worked on in the current beta(s) as per the changelog. Certainly any movie file with multichannel audio should be able to be converted to FLAC, which will solve a number of problems.

But it won't have any effect on the playback of entire Blu-rays, whether from disc/folders/ISOs, since remuxing of course strips all the menus, special features and so on. Not a problem for a lot of users, but the C-200 is supposed to be a Blu-ray player so it'd be nice if it could properly play whole Blu-rays right!

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(11-16-2009 05:21 AM)Willem53 Wrote:  OK... lets assume WMAPro and AAC are multichannel PCM on the HDMI it would make no difference for the majority of users who just do stereo on their TV..right..?
I like the Idea very much but if Microsoft and Apple demand to much of a license fee per unit we will need to wait for the majority to be on Home cinema audio systems and WMA and AAC to make it to the living room as popular audio formats... only place I see them now being popular is the mobile audio scene...... in stereo...

Quite right, multichannel PCM won't be useful for the users who connect direct to a TV. But the old A-series poll, flawed though it might be, showed only a bare majority of users didn't use a home cinema system. And I wouldn't be surprised if more C-200 users than A-series users were connected to home cinema, since again one of the key benefits of C-200 is Blu-ray support, and surely Blu-ray watchers are more likely to use home cinema systems than movie watchers in general.

I agree though that multichannel AAC and WMA are relatively uncommon formats, and if PCH had only so much licensing money to spend I'd definitely encourage them to look at Dolby and DTS first

[michaelr64]

EDIT:
Sorry i misread some parts of it; i thought the plea was for a fully functional blu-ray player.
However
I think it is best to stick with the plea for a fully functional blu-ray player.
The c200 is advertised as being a full-fledged blu-ray player.
With the current settings it can not decode the audio stuff correctly.
If that means that i won't have dts tracks decoded to multi-channel unless there is pip involved that is fine with me.

Although this is similar to multi-channel flacs or dts etc. it is not the same.

This issue here is part of the blu-ray spec and being able to play blu-ray discs is one of it main selling points.

So my question about if Syabas/Werner had stated something about this should really be concerned to this part.

Lets not pollute the topic by dragging in multi-channel flacs in to this.

[peterjcat]

I agree that the most reasonable request is for a fully functional Blu-ray player. However I'm not sure that the issues are really as separate as all that. I don't believe you can get a multichannel DTS decoding licence just for when there's PiP -- I would have thought you either have a licence for all files or for none. However, we all know that when you make an assumption, you make an ass out of you and umption!

I would also be happy enough if multichannel decoding of DD/DTS were available whenever primary/secondary audio mixdown were necessary, but I'd be even happier if it were available all the time.

As I said somewhere else, I think the Sigma logic is trying to do the right thing here: bitstream where there's no PiP track, decode when there is a PiP track. That way, in most cases you'd let the receiver to the decoding, which may bring marginal benefits (even if it's just seeing the lights and knowing for sure what kind of audio you're getting); but if there is PiP then mixdown will be available. However, the logic only works when the player is allowed to decode to multichannel PCM for the purposes of mixdown (including decoding DD+, TrueHD and DTS-HD).

[jj666]

As I understand it, the HDI machines have a setting "best quality" (bitstream main audio, ignore PIP audio), "PiP support" (decode to LPCM and mix audio tracks when needed), so you're right Peter, if the player is decoding to 2CH LPCM only, it's going to be quite useless in that respect.

We'll have to see how the newer SDK from Sigma is handling things with the included Blu-ray fixes Werner was speaking about.

Cheers,

-jj-

[peterjcat]

I think that's pretty a sensible solution; I have heard that the new PS3 does something similar (or might even automatically switch between bitstreaming and decoding when you first invoke a PiP stream, not sure about that though). Of course the PS3 can fully decode TrueHD and DTS-HD so there's no real compromise either way; not sure if the HDI machines can do that or just decode and mix the AC3/DTS audio when PiP support is enabled. I also don't know for a fact whether the Sigma chip can decode DTS-HD but I think it probably can, and TrueHD even more likely.

I'll certainly be awaiting the new Sigma SDK with interest, and hope that I'm wrong about audio decoding being limited to 2-channel for all time.

[Daminite]

i'm beginning to think that i should wait to get a c-200 and just get a used a-110 of ebay to tide me over till they get their act together with the multi-channel audio.

i've been looking at the c-200 as not just an nmt but at a blu-ray replacement as well, but if it doesnt support 7.1 audio $370(counting tax/shipping) and still having to buy a blu-ray drive ranging about $80-$150 is a bit much when i can get an actual blu-ray player for $150 that will do full 7.1 audio and a used a-110 for an average of about $170.

[peterjcat]

That would seem to be a viable option if you want to play Blu-ray discs rather than backups from folders/ISOs -- I'm personally quite keen on the latter so am hoping the C-200 will come to the party.

[noggin]

Just to confuse matters - doesn't DTS now have a DTS Express standard that allows you to bitstream both the DTS HD MA/HR main audio AND a DTS Express secondary audio, all bitstreamed over HDMI, decoded and mixed in the amp...

[Daminite]

well i wouldnt mind iso/folder for blu-ray but i wouldnt even consider doing it till the 2TB hdd's cost what the 1TD do now.

my long term plan is to have a popcorn hour in every room with a tv and an nas set up with all of our dvd and blu-ray iso/foldered. but this is with the intent of hooking some of them up for 7.1.

and depending on how the 3d revolution goes i i'll probably end up with a 3d enabled blu-ray player anyway