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alex.ba · 2011-05-31, 21:10

Hi,

a few information and questions regarding bit perfect AUdio in XBMC.

In General my undersatnding was that using a kernel bypassing mode like WASAPI, Kernel Streaming or Asio should be used for bit perfect Audio. That means all filters etc. that are used by the windows Kernel Mixer are passed by and so the Audio stream can be directly hand overed to the sound card driver.

With this understanding I made some tests and had to leard that the sound that is output via wasapi from XBMC sounds different than this coming out e.g. by foobar and wasapi. The sound of XBMC was liked a bit compressed (can hear that in dynamically themes).

So just to come to the road again. Is there any internal compressing or mixing done by XBMC Audio Engine? If so, it possible to disable this?

Is there any other prerequisite than the WASAPI Methode (e.g. does it work only with certain hardware etc.)

I'm really confues and want to use this great Media Center also for my Audio files.

Can soneone help?

Regards,

Alex

goran__ · 2011-06-03, 19:28

alex.ba Wrote:With this understanding I made some tests and had to leard that the sound that is output via wasapi from XBMC sounds different than this coming out e.g. by foobar and wasapi. The sound of XBMC was liked a bit compressed (can hear that in dynamically themes).

I've noticed a similar problem when playing back DVD's. There is very strong compression in the audio that's coming from XBMC when compared to the sound from mediaplayerclassic -> reclock -> ati hdmi via wasapi. In XBMC I'm outputting to ati hdmi via wasapi and using the resample audio option. The ac3/dts capable options are also off.

Interestingly, it appears that all audio tracks (such as truehd/dtshd) don't suffer from this problem or at least the compression doesn't appear as obvious. Perhaps the audio decoding in XBMC does the compression?

goran__ · 2011-06-05, 21:15

goran__ Wrote:I've noticed a similar problem when playing back DVD's. There is very strong compression in the audio that's coming from XBMC when compared to the sound from mediaplayerclassic -> reclock -> ati hdmi via wasapi. In XBMC I'm outputting to ati hdmi via wasapi and using the resample audio option. The ac3/dts capable options are also off.

Interestingly, it appears that all audio tracks (such as truehd/dtshd) don't suffer from this problem or at least the compression doesn't appear as obvious. Perhaps the audio decoding in XBMC does the compression?

Soo, I've done some testing and it seems that adding <applydrc>false</applydrc> to advancedsettings.xml seems to alter the decoded sound. The audio is still not equal to AC3 passthrough or decoded by whatever the mediaplayerclassic used (probably ffdshow) as the overall level is a bit higher on XBMC. The compression however appears to be disabled.

alex.ba · 2011-06-06, 01:43

Hi,

thank you very much for the Information. I had the chance for testing today and also tried the advanced tweak. I´did not try bitstream Audio (like AC3 or DTS) but flac and a few wav files.

Reference at the moment is foobar with Kernel Streaming. It has a solid and wide basement with absolut neutral and linear middle and high.

The default Player in XBMC (PAPPlayer) in combination with Wasapi unfortuinatelly produces some distortions and sometimes have the impression that the sound is compressed. It is better with the DVDPlayer but has not the Kernel Streaming level of Foobar.

Does anybody here made some test. I tried also the new DSCodec Release but unfortunatelly I did not manage to use the WASAPI Output. The realease of 30th April have some bugs in that and a newer release is not available. Tried to compile it on mys own but got some strange dll errors. Anyway I asked in the thread if someone could compile a newer build.

http://forum.xbmc.org/showthread.php?tid=94645&page=19

I read a topic here in Forum that in combination with Reclock and DSCodec it should be close to the Foobar quality but I have not manged bto get it to work. Will see :-)

Regards

A

PedroSoares · 2012-12-05, 23:49

Even with the new XBMC version 12.0 Frodo, with AudioEngine, the problem persists.
foobar sounds much better.
did you manage to improve sound quality in XBMC using reclock?

DDDamian · (This post was last modified: 2012-12-06, 05:42 by DDDamian.)

(2011-06-06, 01:43)alex.ba Wrote: Reference at the moment is foobar with Kernel Streaming. It has a solid and wide basement with absolut neutral and linear middle and high.

Implying that it changes the data somehow? If so, that's not bit-perfect. If not, that statement is meaningless as bit-perfect players have *no* influence on the audio content or sound.

(2011-06-06, 01:43)alex.ba Wrote: The default Player in XBMC (PAPPlayer) in combination with Wasapi unfortuinatelly produces some distortions and sometimes have the impression that the sound is compressed. It is better with the DVDPlayer but has not the Kernel Streaming level of Foobar.

You do realize that PAPlayer, DVDPlayer and indeed Foobar output exactly the same data??

DDDamian · 2012-12-06, 05:39

(2011-06-03, 19:28)goran__ Wrote: In XBMC I'm outputting to ati hdmi via wasapi and using the resample audio option.

Interestingly, it appears that all audio tracks (such as truehd/dtshd) don't suffer from this problem or at least the compression doesn't appear as obvious. Perhaps the audio decoding in XBMC does the compression?

Why would you use the resampling option? While we do allow resampling to almost any sample rate it will add artifacts. It is only there so people can downsample for certain hardware.

Do you mean decoding? If so the mp3 decoder is widely-regarded as one of the best (libMad), the FLAC is bit-perfect, and the AC3/DTS decoders are ffmpeg...

Musicmaya · 2012-12-06, 09:59

Greetings,

on my quest for bit perfect audio only for 2 channel stereo, have done lot rigorous listening tests, from mid end DAC to hi end DAC.

my observations are as follows.

windows foobar ASIO or WASAPI cant even come near XBMC WASAPI combo...the sound from XBMC WASAPI is more open & spot on,, well in this testing process i have used some very high quality equipment.

well from past few months, i got exposed to OPENELEC 2.0,

should i say by far this openelec configured with alsa just dumps any WINDOWS combo..

off late i am testing the new build of XBMC FRODO and openelec 3.0 beta....still to say the new AUDIO ENGINE is buggy.

when we say bit perfect, it is to single stream of audio which comes from either windows or Linux..

most important in XBMC either Linux or windows

switch off replay gain
switch off cross fade
switch of menu sounds

the final delivery is bit perfect as reported by my DEQX, which is industry standard processor.

my conclusion

XBMC with Linux alsa config rocks

my preference is OPENELEC , which will put foobar to shame. its a pity why people blind folded say foobar is the best for bit perfect.

thanks

**jjd-uk** · 2012-12-06, 12:08

Damain,

I know you're probably busy but if you've time can you take a look at

http://forum.xbmc.org/showthread.php?tid=146361

http://forum.xbmc.org/showthread.php?tid=143255

Both suggest XBMC is not sending audio bit perfect and I'm not qualified enough to argue the toss.

Musicmaya · 2012-12-06, 12:31

(2012-12-06, 12:08)jjd-uk Wrote: Damain,

I know you're probably busy but if you've time can you take a look at

http://forum.xbmc.org/showthread.php?tid=146361

http://forum.xbmc.org/showthread.php?tid=143255

Both suggest XBMC is not sending audio bit perfect and I'm not qualified enough to argue the toss.

indeed XBMC Frodo is sending bitperfect

all the dac's which i have tested report correct frequency lock for 44.1, 96 and 192 kHz ( 16 and 24 bits)

the only problem still i am facing is 48 kHz, all my movies rip and dvd play in 44.1 instead of 48 kHz.also i get crackling noise when i play movies.

DDDamian · 2012-12-06, 16:47

@jjd-uk

I am following some of these threads with amusement Smile

There is a great deal of misinformation, mis-use of terms and just plain speculation in most of the posts.

When I look at them as a whole I think of only one thing: for the first time XBMC is being debated among the audiophile-grade players, something that clearly didn't and could not happen before the AudioEngine code merge when it was stuck in the 16-bit world of the original XBox. That alone makes me pretty happy.

I was one of those who fell in love with XBMC from every aspect except the audio quality. I didn't win many friends on the team with some of my early posts on the subject (waa-waa listen to the whining audiophile lol). Just seeing the debate rolling along from critical audio users is nice to see.

AudioEngine introduced a quantum leap in terms of audio quality and capabilites to XBMC, along with more than a fair share of bugs. There are many features to come, as well as many bug-fixes and behind-the-scenes code changes that end-users will never notice such as performance fixes. It will improve with age as these things do. I do the community more good working on that than debating right now.

As to some of the inner workings: When the time is right I'll put something definitive up on the Wiki as a reference document - so much easier than keeping up with many threads and wading into what will invariably be long debates. I do consider myself strongly-versed in the world of digital audio as well as AudioEngine, and can speak with some authority on both, but not to the point of distraction. When I'm ready I'll put out something based on facts.

In the meantime debate away! Features, bug-reports, or rampant speculation - it's all good.

From a purely audiophile perspective I'll say this: I love the output quality we've achieved - it's night-and-day over the previous code, and we're not even done yet Smile

fat-tony · 2012-12-06, 17:46

Hi DDDamian - glad to see you in a non-Windows specific thread! I've finally made the move back to linux (openelec) from Windows and had to change to an ION2 motherboard with nVidia graphics to get proper multichannel sound from my SACD rips. However I'm having an issue which I think is non platform specific as I had it with the earlier AE build on xbmc. Could you have a look at the attached and see if it looks like an AE bug? Sorry for cross posting, but I'm not getting any traction in the general help thread...

--------------------------------------------------------------------------

I'm running an openelec nightly build of Frodo (built 24/11/2012) on my ION2 system. Since I replaced my old AMD Fusion motherboard (which doesn't support HD audio on linux) with the ION2/ Nvidia board I have been able to play my multichannel FLAC rips of my SACDs in all their surround glory!

However, I am experiencing an issue if I try to skip between tracks rather than letting them play through in sequence. xbmc seems to think there is an audio format change and briefly switches back to the default 44.1kHz stereo format and then back to the correct multichannel format. This causes my receiver to "click" and I lose the initial second or two of audio in the next track.

This issue is not specific to openelec as I had the same problem on Windows (where the Fusion motherboard supported multichannel HD audio).

In the attached log, please look at time 16:20:41 where the 88.2kHz, six channel audio starts. Then at 16:20:56, when I skip to the next track which has the exact same audio format, but xbmc briefly switches to 44.1kHz two channels and then back to 88.2kHz six channels. I let the next track play all the way through and xbmc handles the track transition correctly at 16:23:47. I then skip to the next track at 16:23:47 and the problem recurs.

http://pastebin.com/BSetPYmy

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waltermalter · 2012-12-06, 21:26

@fat-tony: Wrote you also a PMabout SACD, but forgot to ask you play the multichannel files in XBMC. Do you chose DVDPlayer for those files?

Cheers,
Walter

DDDamian · 2012-12-07, 07:09

@fat-tony - hey mate Smile

yep that needs fixing. I'm revamping some the the OpenSink() code to address this, along with a related glitch 5 seconds before a track change where the channel count or sample rate changes. This one annoys the hell out of me Tongue

PS - my private builds now play SACD Smile

@waltermalter - they should play in either player.

fat-tony · 2012-12-07, 14:04

@DDDamian - thanks for the info, thought it might have been a bug all right as it was happening both on Windows and linux platforms. The openelec ION builds are damn near perfect at this stage, supporting HD audio and PVR so I have everything working on one box. It's a pity that the AMD/ATI drivers on the Fusion platform still don't support HD audio over HDMI (on linux), so the ION2 and Intel mobos are the only choice for audiophiles.

@waltermalter - I've replied to your PM, giving you details of my struggle with PS3 SACD extraction.