Full TrueHD Quality without HDMI?

[cmw]

Ok, I'm posting for a friend of mine here who has a rather specific question about a topic I know nothing about, but I hope you guys can help.

He's considering buying a Bluray Drive for his PC but has reservations about his potential Audio Quality: His problem is that according to AACS specifications, when not using HDMI the software player (like PowerDVD) HAS TO downsample the multimbit++ 192khz track to something around 640kbit/s, 48khz, obviously decreasing quality in a kind of extreme way. Now the simple question is: Is there any available player that doesn't necesserily follow the specifications and well, just plays the original stream without downsampling, when no HDMI is available?

Best regards

[Doom9]

His problem is that according to AACS specifications...Could you point me to the specific section in the specs that says that? Mandatory downsampling is new to me.. I'm only aware of ICT but that only applies to video and the ICT isn't widely used.
Also, your friend is definitely mistaken about HDMI... the way display and audio playback devices are connected is not specified. When using a digital link, some sort of copy protection has to be used... either HDCP or Microsoft's DRM. HDMI is just one of the physical standards for connectivity that happens to implement HDCP. DVI is another (has no audio though), DisplayPort is another (I haven't seen an implementation that also uses audio but the specs would allow it).

I think your friend misunderstood the physical constraints of audio output over non HDMI: S/PDIF simply doesn't provide enough bandwidth to transport the high bitrate audio streams commonly found on high def discs. Hence, audio has to be downsampled if you use S/PDIF to connect your Blu-ray player (for the matter of this discourse a PC with Blu-ray equipment is equal to any Blu-ray standalone player) to your receiver. That has nothing to do with DRM though. Since at some point you have to go analog (the latest possible point being the receiver), I'd see very little sense in enforcing downsampling in case when audio is being decoded by the player (=by your software player in this case)..

There are further constraints that concern HDMI but that also don't have anything to do with DRM: only HDMI 1.3 allows bitstreaming of TrueHD and DTS MA audio.. if your player or receiver has a lower version of HDMI, then your player will have to decode the audio and the decoded PCM stream will be transmitted over HDMI, however, it seems HDMI is capable of transmitting 8 channels of 24bit 192KHz audio so that shouldn't be an issue (although iirc the PS3 has some limitations in that mode but I could be mistaken).

[rica]

I have a Creative SB-X Fi sound card and an SR503E Onkyo receiver. The player is Arcsoft TMT and OS is Vista 32 SP1.
I use the analog outputs.
In theory, i should have sent decoded analog signals (pcm/digital decoded by TMT and analog signals converted via X-Fi DAC to receiver over analog cables)
But the question i have to adjust receiver to DVD Direct/Multichannel mode which means analog signals reconverted analog to digital in receiver and go to DAC of the receiver and reconverted to analog again.
So i would never understand whether 24 bit is going directly or not, unless giving it a go; sending the direct analog signals to a multichannel analog amplifier. (which i don't have)
But btw, it sounds good to my ears; that's all. No evidence...

[madshi]

It is true that e.g. PowerDVD does downgrade decoded audio to a max of 48khz and 16bit. That is far from "decreasing quality in a kind of extreme way", though. It will be barely noticable, if done a really good way (using proper resampling/dithering etc). However, who knows if PowerDVD does use proper algorithms for the downconversion? Also it's hurting to know that PowerDVD does downgrade audio at all.

I'm not sure if ArcSoft also downgrades audio.

AFAIK there is a rule that you have to downgrade audio, if you want to send it digitally and if it's not really really well protected. PowerDVD might someday enable full quality, but first they need to get the Microsoft's PAP (protected audio path) pipeline working. The problem is that PAP is far from finished. And it will probably never work in XP, maybe not even in Vista. See also this:

http://amplioaudio.blogspot.com/2008/12/its-been-awhile-problems-playing-blyu.html

The proper solution to this problem is to either bitstream the audio through HDMI to your receiver. Unfortunately AFAIK current HTPC HDMI ports don't support bitstreaming yet.

Or alternatively you can transcode the audio data to an open format by using proper decoders (which of course shouldn't downconvert by themselves). That is one of the main purposes of my tool "eac3to", which will take any audio format used by HD DVD and Blu-Ray and transcode it to an open format without downgrading audio one bit. E.g. LPCM, TrueHD and DTS-HD Master Audio tracks are transcoded to FLAC. When later playing back these FLAC files with an open source media player like MPC HC, audio is played back and passed to the receiver in full quality. Of course this solution works only if you transcode the audio data to something else and if you stop using PowerDVD/ArcSoft etc for playback...

[cmw]

Thanks for your input everyone, my friend will resort to the transcode to FLAC method. It's sad to know that you basically have to pirate/rip the disc to get full quality :/

[rica]

I am still unsure that TMT downconverts audio while i'm sure Power DVD does...

[Doom9]

Hmm.. forgot about PAP. However, doesn't that essentially apply to video, too? Do we have a protected video path through the system (in XP) or did they simply not follow the requirements there? And wouldn't PAP be tied to AACS (thus meaning if you have AnyDVD HD running no player should downconvert)?
If you don't need navigation, I doubt the open source audio decoders care about PAP.. so perhaps mplayer or vlc would suit you unless it's DTS HD MA audio.

[madshi]

Hmm.. forgot about PAP. However, doesn't that essentially apply to video, too? Do we have a protected video path through the system (in XP) or did they simply not follow the requirements there?
It seems that video transport is strict enough, so there's no downgrading necessary.

And wouldn't PAP be tied to AACS (thus meaning if you have AnyDVD HD running no player should downconvert)?
In theory, yes. In practical life PowerDVD does downconvert regardless of whether the content is AACS protected or not.

If you don't need navigation, I doubt the open source audio decoders care about PAP.. so perhaps mplayer or vlc would suit you unless it's DTS HD MA audio.
Correct, open source decoders don't care about such stuff. There's no open source decoder available for DTS-HD, though, and I don't know how stable the ffdshow TrueHD decoding support is. Also I don't know if the ffdshow TrueHD decoding supports more than 16bit. You know, libav's audio processing was once limited to 16bit, and it might still be (I'm not up to date on that). The safest way right now is to transcode lossless audio to FLAC by using eac3to and then playing that back by using madFlac. That gives you 100% quality.

[lexor]

His problem is that according to AACS specifications, when not using HDMI the software player (like PowerDVD) HAS TO downsample the multimbit++ 192khz track to something around 640kbit/s, 48khz, obviously decreasing quality in a kind of extreme way.

That doesn't sound like a requirement to downsample, sounds more like the requirement to fall back to AC3 stream (embedded in TrueHD track in Blu-ray and optionally for HDDVD) for situations where HDMI is not available. For those people who still only have an A/V receiver with only Dolby AC3 support, not even DTS. (yes people like that own blu-ray, I had to help some of them out converting stuff for their receiver).

Without that requirement, such users will get no sound.

Alternatively, it could be talking about plugging the "analog hole" in **AA's butt, meaning you can't transport the new fancy formats over analog components. (and SPDIF components don't have the bandwidth, thus leaving you with HDMI only).

[rica]

I just gave it a go again:

First trial) I extracted dtshd (DTS-HD MA) as is with eac3to (v.2.85),
remuxed with video via TSMuxer. (m2ts)
Second Trial) This time transcoded to flac directly from the original with eac3to.
[a03] Extracting audio track number 3...
Decoding with ArcSoft DTS Decoder...
Encoding FLAC with libFlac...
Creating file "G:\CETK\new\audio.flac"...
The last DTS frame is incomplete and thus gets skipped.
The original audio track has a constant bit depth of 24 bits.
Video track 1 contains 20937 frames.
Remuxed with video via MkvMergeGui. (mkv)

Later i played both of them on MPC with these chains:

DTS-HD:

FileSource(Async) > ArcsoftMpegDemux > ArcsoftVideoDecoder > EVR Custom
>
Arcsoft AudioDecoder HD > DefaultDirectSound Device

FLAC:

FileSource(Async) > ArcsoftMatroskaSplitter > MPCVideo Decoder > EVR Custom
>
MadflacDecoder > DefaultDirectSound Device

(Important Note: If you use Arcsoft Audio Decoder HD; everytime you have to correct to 5.1 on filter properties page.)

I/ or my ears have never found out any sound difference between them.

So my question is:

What makes this downconverting? -if there is...

If it is commercial decoders, how Arcsoft allows Libav to encode to 24bit if it doesn't decode as is? (24bit)

If it decodes as is how this downsampling occurs?

_ _ _ _

[madshi]

I don't know if ArcSoft downconverts or not. If it does, it might be hidden somewhere in the DirectShow decoder or maybe in the ArcSoft player software itself. Can't say...

[rica]

I don't know if ArcSoft downconverts or not. If it does, it might be hidden somewhere in the DirectShow decoder or maybe in the ArcSoft player software itself. Can't say...

You don't know??

MadFlac pininfo shows the right info while Arcsoft's doesn't:

http://img120.imageshack.us/img120/1184/madflacpx3.th.png (http://img120.imageshack.us/my.php?image=madflacpx3.png)

Do you think it is up to your splitter's success? :)

When are we meeting your madsplitter.ax?

_ _ _ _

[madshi]

MadFlac pininfo shows the right info while Arcsoft's doesn't
So ArcSoft shows 16bit in the pin info? In that case obviously ArcSoft downgrades audio, too (except when being used by eac3to).

Do you think it is up to your splitter's success? :)
It doesn't have anything to do with the splitter. It's probably the way the decoder is called. eac3to calls the ArcSoft DTS decoder directly and partially bypasses DirectShow. While in GraphEdit you have no other choice than to go the usual DirectShow route, which might include downgrading...

[rica]

So ArcSoft shows 16bit in the pin info? In that case obviously ArcSoft downgrades audio, too (except when being used by eac3to).


Yes. (tried with 128 which Arcsoft himself anxious about 24bit in this version. I'll give it ago with 126 someday.)



It doesn't have anything to do with the splitter. It's probably the way the decoder is called. eac3to calls the ArcSoft DTS decoder directly and partially bypasses DirectShow. While in GraphEdit you have no other choice than to go the usual DirectShow route, which might include downgrading...

Thanks for the exlanation.

_ _ __

[Coolpplse]

The safest way right now is to transcode lossless audio to FLAC by using eac3to and then playing that back by using madFlac. That gives you 100% quality.

I personally found that even if we use madFlac that it still follows Vista's shared mixer where if u give madFlac 24bit 96khz 5.1 material, if ur shared mixer is set at 16 bit 48khz or 24 bit 48khz Vista will downsample the audio.... and it does show up when I use LPCM 7.1 output via HDMI from the laptop's HDMI port to the A/V Receiver...

Unless this is an issue that just revolves around my setup, the "purest" form of output that would ever come out of a pc in LPCM form would be the converted FLAC played out on foobar2000 with the Vista Exclusive Mode plugin.... Essentially this would function like "Pure Direct" modes for many Digital A/V Receivers dealing with Digital inputs :)

I did not update to the latest version of madFlac, but unless theres code in the latest version of madFlac that takes advantage of the Exclusive Mode found in Windows Vista... the Vista mixer "may" downsample the audio depending on the chosen setting and content

[madshi]

Bypassing the Windows built in mixer is not the task of a DirectShow decoder filter. It is the task of the audio renderer. You can try using ReClock which is an audio renderer which features Kernel Streaming support. That should bypass the Windows mixer...

[rica]

..try using ReClock which is an audio renderer which features Kernel Streaming support. That should bypass the Windows mixer...

Yes, that is what i do as well.

[rica]

Hi madshi, happy new year.

I'm a little bit confused.

Today i make a mkv following this way: (what you suggest)
1)Demux/remux to mkv video and demux audio/transcode to flac with eac3to at the same command line.
2)And remux to mkv container with MkvMerge Gui.

Used MPC-HC to watch it with my config.
(I have a Creative SB-X Fi sound card and an SR503E Onkyo receiver. OS is Vista 32 SP1.
I use the analog outputs.)

Used reclock to bypass Windows' mixer; here is the graph behind the MPC-HC:

http://img231.imageshack.us/img231/3416/madflaclatestsp7.th.png (http://img231.imageshack.us/my.php?image=madflaclatestsp7.png)

While watching it i tried to listen System Sounds like "Windows Logon" to understand whether the mixer is interfering or not. In theory i must not hear the sounds but i do.

Madflac pin info gives 24bit but does mixer interfere and downscale it to 16?

Or?

[yesgrey]

Used reclock to bypass Windows' mixer

Have you set reclock to use kernel streaming with PCM sound?
Is the volume slider working? If it is, you are not bypassing kmixer...

[rica]

Have you set reclock to use kernel streaming with PCM sound?
Is the volume slider working? If it is, you are not bypassing kmixer...

Yes i have.
Even main mkv gives no sound when kernel streaming has been selected, kmixer is still working; i still hear windows log on sound.
Tried with onboard audio driver as well. Nothing has changed.

[rica]

There is no other choice when i select kernel streaming but "default device" while direct sound and wave out recognize the SB.
So i suppose kernel doesn't recognize the audio card?

http://img71.imageshack.us/img71/6083/kernelli5.th.png (http://img71.imageshack.us/my.php?image=kernelli5.png)

[The_Keymaker]

Have you set reclock to use kernel streaming with PCM sound?
Is the volume slider working? If it is, you are not bypassing kmixer...

His OS is Vista 32 SP1 and there is NO Kmixer in Vista. Vista has a MUCH more effective and elegant mixer than XP's Kmixer.

You can bypass Vistas mixer by having a player or renderer capable of operating in Exclusive mode via WASAPI output.

The_Keymaker

[rica]

His OS is Vista 32 SP1 and there is NO Kmixer in Vista. Vista has a MUCH more effective and elegant mixer than XP's Kmixer.

You can bypass Vistas mixer by having a player or renderer capable of operating in Exclusive mode via WASAPI output.

The_Keymaker

How? .......

[Coolpplse]

His OS is Vista 32 SP1 and there is NO Kmixer in Vista. Vista has a MUCH more effective and elegant mixer than XP's Kmixer.

You can bypass Vistas mixer by having a player or renderer capable of operating in Exclusive mode via WASAPI output.

The_Keymaker

Is this possible with Media Player Classic HC and madFlac Decoder? Based on how the renderers are connected, they dont seem to bypass Vista's mixer as of right now...

[rica]

Yes i have.
Even main mkv gives no sound when kernel streaming has been selected, kmixer is still working; i still hear windows log on sound.
Tried with onboard audio driver as well. Nothing has changed.

Hey guys,
I've been still wondering the answer?

[mrcorbo]

A request has been put in to add WASAPI exclusive mode output support to Reclock. If this is implemented than it will allow any DirectShow player to output bit-perfect audio in Vista, providing the sound drivers support this mode of operation.

[rica]

A request has been put in to add WASAPI exclusive mode output support to Reclock. If this is implemented than it will allow any DirectShow player to output bit-perfect audio in Vista, providing the sound drivers support this mode of operation.

Thanks; good news.

[rica]

BTW, i did my homework today.

Here is how to bypass Vista's mixer:

http://wiki.hydrogenaudio.org/index.php?title=Bypassing_Windows_Mixer

I used foobar2000 with its WASAPI plugin :

http://wiki.hydrogenaudio.org/index.php?title=Foobar2000:Components_0.9/WASAPI_output_support_%28foo_out_wasapi%29

And got undownconverted audio for the first time:

http://img207.imageshack.us/img207/9693/wasapiww0.th.png (http://img207.imageshack.us/my.php?image=wasapiww0.png)

BTW, there was an interestig note:

Alternate solutions
Windows Vista lets you control what data format gets sent to your soundcard so you can get rid of the resampling step without bypassing the mixer by setting mixer's output sample rate matching the sample rate of what you play (44100Hz for CD-sourced material).
Retrieved from "http://wiki.hydrogenaudio.org/index.php?title=Bypassing_Windows_Mixer"

Dunno it works?

http://img105.imageshack.us/img105/9536/vistamixertm4.th.png (http://img105.imageshack.us/my.php?image=vistamixertm4.png)

(I got a flac via eac3to and gave it a go with Foobar2000.)

Hope reclock makes it in the near feature.


_ _ _ _ _

[The_Keymaker]

A request has been put in to add WASAPI exclusive mode output support to Reclock. If this is implemented than it will allow any DirectShow player to output bit-perfect audio in Vista, providing the sound drivers support this mode of operation.

Slysoft has now added WASPAI output to reclock ;)

http://forum.slysoft.com/showthread.php?t=19931

The_Keymaker

[Socio]

I am still unsure that TMT downconverts audio while i'm sure Power DVD does...

TMT does downconvert, some earlier builds donconverted then up converted however.

*There is one exception is the special .125 version that comes with the ASUS Xonar audio card which does not downconvert.

[rica]

TMT does downconvert, some earlier builds donconverted then up converted however.

*There is one exception is the special .125 version that comes with the ASUS Xonar audio card which does not downconvert.

Thanks but already have found the answer i think :)

http://www.avsforum.com/avs-vb/showthread.php?p=16057058#post16057058