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Author Topic: Bluetooth speaker behavior wonkiness  (Read 1994 times)

steven.porteus

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Bluetooth speaker behavior wonkiness
« on: December 22, 2013, 10:12:33 am »

So, somethings is not making sense to me and maybe I'm missing something on the MacBook/OS X architecture here.  Or maybe this is a Media Center nuance that I'm not getting.

I have a MacBook Pro Retina (2013).  Most of my music is FLAC and some high def (192/24).  So, I've got the DSP in Media Center set to downsample anything over 96K down to 96K because that's all the MacBook Pro DAC can handle (very disappointed in Apple for this by the way.).  Anyhow, all is well and good when I play through internal speakers.  But, I connected my SoundFreaq Sound Kick this morning and started getting output warnings that it could play because of the output capability. Low res files would plan OK, but not the higher res files. I tried disabling the DSP and changing the output from core audio to the bluetooth speaker and neither actions seems to be making a difference.  If I downsample everything to 44.1, it works.  Now, I'm pretty certain this was working as expected when I was running the Media Center trial previously.  I am on the current build of Media Center (19.0.100).

So, here's my puzzlement.  Isn't the sampling rate restricted by the DAC capability and really have nothing to do with the speakers that output is going to?  Doesn't the file move through the internal sound chip DAC and then get redirect to either the internal speakers, plugged in speakers/headphones, or bluetooth for analog output??  What would Media Center or OS X care about what the speaker is that is handling the analog audio?  Why would that be considered "the output" when it should be routing through the core audio default?

I know there is a logical answer to this that I'm missing, but apparently critical thinking on the weekend is beyond me!

Thank you.




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6233638

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Re: Bluetooth speaker behavior wonkiness
« Reply #1 on: December 22, 2013, 10:42:49 am »

There are two main ways that you can handle output from a media player like Media Center:
 
1. You can send the audio to the system audio mixer, which will generally accept anything you throw at it, and let it figure out what formats are supported by the connected hardware and resample to whatever it deems best.
2. You can have the player bypass the system audio mixer (also known as "bit-perfect" output) and take control over the playback device directly.
 
In scenario #1, the system might see that the hardware is capable of up to 96kHz and decide that it will resample everything to that, no matter what the input is.
In scenario #2, the player will take control over the hardware so that when you send it a 44.1kHz file, the hardware is outputting 44.1kHz rather than resampling it.
 
The issue is that most hardware does not accept all input formats, so if you were to send 96kHz hardware a 192kHz file, playback will fail with an error in scenario #2.
This is why Media Center offers controls to let you resample any input rate to whatever output rates suit you.
 
Some hardware might accept up to 96kHz but lack support for 88.2kHz for example, so you might want to resample that to 44.1kHz rather than 96kHz.
 
 
In your case, the best solution would probably be to set up separate zones for your MacBook's internal speakers, and another zone for your Bluetooth speaker, with separate output formats selected for each.
 
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