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Bit Perfect playback with Windows 7 x64 iTunes and Lynx AES16 possible?


epiekarc
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Hello All,

 

I am setting up my HTPC to be able to output bit perfect to my ARC DAC7. I'm using my AES16 sound card over XLR to feed my DAC7, although just so you know, I also have a Xonar HDAV1.3 sound card for Master Audio BD playback. I'm currently using TMT3 for BD play back, which allows me to select audio output to my xonar card that is pass-through. I'm looking for a similar way to output audio to my DAC. Like I said in the subject I'm using Windows 7 64 bit OS and I would really like to use iTunes. I currently own J. River Media Center and MediaMonkey Gold along with the iPhone remotes; in my opinion they have terrible user interfaces. I will only be using my iPhone to control the system and the iTunes remote works a lot better. How can I get bit perfect playback out of iTunes? I've already spent a lot of time and money setting up this system, so I am really looking for the easiest and best solution. Thanks for all the help.

 

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Hi epiekarc - Unfortunately you're in for an uphill battle. Since iTunes does not allow one to select the audio output or configure anything that has to do with the audio output, it can be tough and sometimes impossible to get bit perfect with iTunes on Windows. I haven't tried iTunes on Windows 7 64 bit yet. I do have it here and running with a Lynx AES16e card, so I'll give it a spin when I have a bit of time.

 

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Hello Chris,

 

Thanks for the quick reply. I'm wondering if this thread here http://www.head-fi.org/forums/f46/itunes-9-has-wasapi-updated-zune-4-also-has-bitperfect-out-444468/ which talks about some QuickTime adjustments means bit perfect playback is coming. I won't be able to try this for a couple days, but I am very hopeful that there may actually be a solution coming. Also, if iTunes is a no go, do you have any player suggestions? Thanks again for the help.

 

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I have explained on some other threats here, why the DTS or Dolby or HDCD test is no test for measuring Bit-True or not Bit True.

 

And especially with iTunes under Windows Vista or 7, you have two audio systems in series. Under Vista and 7 you can have the case, that you play back a 44.1 K Audio CD file and have set your Vista and 7 to 44.1 kHz output, but on the way from the HDD to the Output, the signal goes through QuickTime, that can be set to upsample to 96 kHz and then afterwards Windows Mixer downsampled back to 44.1 kHz. So is this Bit True? I guess not.

 

If you like the UI of iTunes a lot, then you have to use it on a Mac with Amarra. Under Windows there is not way to get Bit Perfect Data (and good sound) with iTunes.

 

But if you want to use a Windows System (Vista or 7), I would suggest using J.River MC 14 (or Foobar2000) in order to get Bit Perfect Out and good sound.

 

Juergen

 

 

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Well, if I'm forced to use something besides iTunes, my next choice would be J. River, I just wish they would design a better iPhone remote app. So, I'm sure this has been covered but after several Google searches I still can't find it, where can I find instructions for setting up J. River for bit perfect playback? Like I said earlier, I'm using a Lynx AES16 for audio out with a custom cable I bought from Redco that has only one XLR connection. Thanks again for all the help.

 

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On Vista, anyway ( and I would assume 7 is the same ) providing all your material is at the same sample rate.

You have to: Set the Windows output ( properties->Advanced ) to be the sample rate you want ( normally 44.1k ), and then set the audio output rate in the Quicktime control panel to be the same. Start up iTunes, and all should be good...

 

 

your friendly neighbourhood idiot

 

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Setup up iTunes / QuickTime in Vista and Win 7 with the same sample rate as the source and as the Windows Output prevents you from sample rate conversion, that’s right, and does fulfill the DTS Test, that’s also right; bit is still not bit true.

 

If you follow the advice from J.River to setup the DSP Out to 24 Bit, and de-select padding 24 bit to 32 bit, then using the exclusive WASAPI Mode will deliver your Bit Perfect Out on Vista and Win 7, with automatic sample rate change.

 

Juergen

 

 

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I measured iTunes on Vista using these steps, and the bits coming out matched the bits in the files. I should have mentioned you need all the volume controls at full scale...

 

You are correct - any changes in sample rate will cause this not to be true,

 

your friendly neighbourhood idiot

 

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http://www.designwsound.com/dwsblog/?p=1718

 

Here's Kent Poon's article on bit-perfect with iTunes on a PC,

He had earlier reported that it was only possible at RBCD, and failed on higher resolutions.

 

IN this article he is explaining that you need to switch sound properties & Quicktime settings for sample rates higher than 44.1 in order to retain bit perfect.

 

Sounds like a PITA, but does NOT sound like it's impossible. If the comment by Hercules is correct, it sounds like it's more difficult with Windows 7, due to need to also sync the sample rate of QUicktime.

 

Clay

 

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I am extremely busy, because I have to finish an issue until Wednesday. But I will recheck this on Thursday. I have measured over 20 playback programs in Windows for native bit true playback and none of the programs, that could not bring out ASIO, ASIO4ALL or Exclusive WASAPI (or KS) could deliver bit true results.

 

With WASAPI and also with ASIO4ALL it is possible to put out 88.2 kHz Bit True, so does iTunes in Windows Vista or Win 7 bring out this sample frequency? Any feedback?

 

Juergen

 

 

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So I can't comment.

 

I do know that 88.2k in Vista is problematic, but 44.1,48 & 96 all seem OK using iTunes, assuming all the sound enhancers are off, volume is full, and the Quicktime control panel, Windows control panel match the rate of the source files.

 

NB This is NOT true for XP

 

your friendly neighbourhood idiot

 

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The 88.2 “problem” exists in every Vista revisions and I thought (or have read) that this should be solved in Windows 7 but it isn't. Without WASAPI you still can't play back natively 88.2 on Windows 7 nor on Vista. In XP could play back every Sample Rate.

 

I guess I will re-check the actual iTunes 9.02 with Windows 7 native playback on Thursday and will post the results here.

 

But in the case (what I do not think, but I will recheck) that iTunes with correct settings in QuickTime and Windows Sound System could deliver Bit True out, besides playing back CD Audio Data it will be absolutely unconformable to uses this as an audio server with different sample rates, because than you have to change on two locations the settings in order to avoid SRC.

 

Anyway, I will recheck when I have finished my actual project and will post it here.

 

Juergen

 

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I am sorry, that I can write only text here at this post; otherwise it would be much easier to not only read, but also see my measurement results.

 

I have done a lot of Bit True Tests with a lot of playback software on a lot of operating system. For the reason of this post in Computer Audiophile, that iTunes should be able to play Bit True under Windows 7 or Vista when set up QuickTime and Windows Output correctly, I have repeated this one test for one more time and came to the same result as with all other tests that I made before.

 

Under Windows 7 and Windows Vista it is only possible to get native Bit True Out when the playback program supports the Exclusive WASAPI Mode (or via ASIO4ALL wrapper, if the program supports ASIO out, or via Kernel Streaming (very rare these days)). There seems (or is) no other way to have native Bit True Out.

 

Measuring iTunes under Windows 7

 

For this test I was using:

Windows 7 Home Premium 32 Bit (but tested also on a 64 Bit machine).

The latest iTunes 9.0.2.25 with the latest QuickTime 7.6.4 (1327.73)

 

Settings in Windows:

 

I have set the level of the Windows Audio Out to 100.

I have disabled all Audio Features

I have set the Audio Out in Windows to 24 Bit 44100 Hz

 

Settings in QuickTime

 

I have set the Output Sample Rate and Bit Depth to the same as in Windows, so 44.1 kHz and 24 Bit. I have tried all three different Output Modes: Wave Out, Direct Sound and WASAPI Out but the different output modes doesn’t change the result under iTunes (see Windows Mixer result).

 

Results of the Bit True Test

 

It is clear, that I have set up the volume in iTunes to 100 and left all audio features disabled.

 

Then you can see that neither the 16Bit DC Signal on the left channel is correct, nor the 24 Bit walking zero signals on the right channel is correct.

 

It is also important to note, that with this setup, playback program that the sample rate at the output doesn’t automatically change with different sample rates of the source signal.

 

Look at the Windows Mixer

 

While I play back the signal, I opened the Windows Audio Mixer and there you can see, that in Windows 7 and Windows Vista, every device has his own Audio Path so when playing back via iTunes, you see that on iTunes Out there is a audio signal and also on the summing point at the output of the sound device, so definitely, the Windows Mixer is working and does corrupt the data.

 

Result without WASAPI

 

I have also absolutely the same result, when I use the Microsoft Media Player in Windows 7 or Vista. Natively, there is no Bit True output and also no automatic sample rate change with those programs.

 

Measuring Exclusive WASAPI under Windows 7

 

When I am using J.River MC14 or Foobar2000 (with the WASAPI out Plug-In), I get 100 % Bit True out under Vista and Windows 7 and also automatic sample rate change.

 

Results of the Bit True Test

 

Here you can see that the 16Bit DC Signal on the left channel is correct (Bit 2 till 16 are all One and the MSB is Zero), and the 24 Bit walking zero signals on the right channel is correct (Bit 1 till 24 are all One except one Bit, that is Zero and is walking integer synchronous with the sample rate).

 

Look at the Windows Mixer

 

While I play back the signal, I opened the Windows Audio Mixer and there you can see that neither the J.River Media Center Out, not the Summing Out does show any action. That means that the signal does not go over the Windows Mixer System, it goes straight from the application to the hardware. Absolutely 100 % Bit True and not corruption of the data.

 

I have made some explanations easier and not so detailed and technically correct, because I do not want to dip to deep into this point and do not want to make this explanation to long.

 

Final Words

 

Under Vista and Win 7 go with Exclusive WASAPI Mode and you will have 100 % Bit True out, with automatically sample rate change and a very good sound and not other windows signal will ever disturb your listening experience.

 

Juergen

 

PS: On the article of Kent Poon, it looks like that he has used an relatively old Windows Operating System (I have found no word witch version) and an older version of QuickTime. So definitely this result from him does not belong to Vista or Win 7.

 

 

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I have hooked up some other PCs and repeated some tests that I have done before. I have measured the native output at the USB Port at 24 Bit 44.1 kHz with my AP Measurement System.

 

In every setup, I have all volume controls to the max (100) and all additional audio features disabled, have set the output in every program to 24 Bit and 44.1 kHz. Here are some results:

 

Windows Media Player 12.0.7600.16415 under Windows 7: not Bit True.

 

Windows Media Player 11.0.6002.18111 under Vista SP2: not Bit True.

 

iTunes 9.0.1.8 with QuickTime 7.6.4 (1327.73) under Vista SP2: not Bit True

 

iTunes 8.2.0.23 with QuickTime 7.6.2 (1324) under Vista SP2: not Bit True

 

Juergen

 

PS: What do you mean with post some files, do you mean the test signal? Do you have an Audio Precision Measurement System for testing (or something similar), so these systems do create by them self test signals for Bit True testing.

 

 

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I have made a lot of investigations to find out a method to be absolute sure, whether a digital system is Bit True or not.

 

I also tried the comparing Wave method, but found out, that I can cheat it. With comparing an digitally kept files of an output and compared it to the file itself, you are have two “imperfections” in your comparison and that is the digital out path and the digital in path. And if both paths, share the same “error”, but only inverse, than your comparing wave test will indicate do difference and you would believe, that it is bit true, but this is not a 100 % proof indication.

 

Just one easy example. In real live, it isn't that easy with different sound drivers, but I just want to explain it easy, why this is not a safe test for testing Bit True. If your audio architecture has the same behavior on the output and the inversely behavior on the input, than your difference of both signals would be Zero and you would think, this is Bit True, but isn't.

 

So the test signal in the Audio Precision is absolutely known by the system and you can describe this mathematically. The digital out in put of the AP is pure hardware, so not driver is involved and the wave files are also available on a data cd rom. So when I play back this test signal with my computer feeding the audio precision, then I can clearly see, whether the signal is corrupted or not.

 

In Vista and in Windows 7 you can have with direct sound out very good measurement results. For example THD products all below – 175 dBFS, or digital black between the bins of the J-Test, so you would think, this must be Bit True with this high performance, but still it isn't.

 

I hope that it is clear what I wanted to describe, that comparing files is a good idea, but if you have inverse behavior on the output to the input, which is not so unusual with the same audio architecture, that it is no indication whether your output is bit true or not.

 

Juergen

 

 

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I'm generating a WAV file, of known audio ( counter, walking one, impulse, sometimes audio ).

I play that back.

I capture the data.

I then compare (not inverse) what I know was in the original file with the output from the computer.

If all the bits I read are the same as the one I wrote into the WAV file, then that is good. Otherwise, it is bad.

 

I don't have the kit available at the moment, but I'll try again when I do.

 

What I meant was: When the AP says "not true", does it tell you any more? In my case, because I have the two files, I can normally work out the processing going on.

 

your friendly neighbourhood idiot

 

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Juergen ....

 

How are you getting bit perfect output with automatic sample rate conversion in J River MC14 with WASAPI and Win7?

 

In the Win7 Audio devices you have to set an output sample rate, either 44.1 or 44 or 96 ...

 

If I set 44.1 and send via J River a 96k signal I get an error. If I set 96 and send via J River a 44.1 signal I get an error. Only when I set J River and Win7 to match do I get no errors.

 

Thus, I can get bit perfect for 44.1 or 96 sources, but I can't seem to get automatic sample rate conversion.

 

What am I missing?

 

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  • 2 months later...

Hi everyone,

 

OK, so bit-perfect from itunes in any PC is always hard if not impossible to acheive (not discussing who's right), but for 90$ there's very simple way: Apple's Airport Express! It's a Wifi audio streamer (works via ethernet too) with an optical out that has been declared by stereophile as bit-perfect. Just select the device as your output in itunes and that's it. I have never heard this not to be true in PC. Maybe you guys care to test it?

 

Now the sad part for me is that I tried it and the digital out did not work properly: with itunes9 (and you do need 9 for any sync with ipod) there was an incompatibility with my DAC so I gave up. But that is my case, the device works OK for many others. Just get it in a place where they take returns.

 

Hope this helps someone...

 

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The major problem with the airport express, the way I see it, is that it still won't allow me to use my Lynx AES16 card. There is more to bit perfect playback than just getting it out bit perfect. The other concern, for many of us is clocking and asynchronous is really the only way to go. That's why we pay quite a bit for a card like the AES16, it allows us to get a very consistent and clean output. If I've said anything wrong, I'm sure I'll be corrected, but to the best of my knowledge that would be some major (IMO) hold backs.

 

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I have forgotten to send you an answer to your question, so here it is.

 

Under Windows 7 and Vista, if you have set the app (either J.River or Foobar) not correctly, you will not have an automatic sample rate change. So so watch if the sample rate of the system changes with different files is a good indication, whether you have set the playback app correctly or not.

 

In J.River you only have to set in the DSP field, to limit the output word length to 24 Bit and in the WASAPI setting you have to try the function “play 24 bit as 32 bit” with your soundcard. Some need this point to be set, some need this to be disabled. So try both until you get a play back.

 

If you set this two points correctly, it doesn't matter what sample rate you have set in the Audio Setup of Windows. You will even recognise, that you will be able to play back 88.2 kHz with exclusive WASAPI, even if you can't select it in the Audio Setup of Windows.

 

Good luck, that should not be too difficult.

 

Juergen

 

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