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2009-05-28, 05:27
In the release notes for babylon it said that the audio resampling was removed. I assumed that it means I can pass through pcm and ac3 bit streams without resampling. The ultimate test of this is supposed to be a 44.1MHz DTS or Dolby Digital ac3 stream passed through to a DTS/ Dolby Digital decoding cable receiver. I have set up my audio card and bit-perfect works exactly as it should with foobar. The 5.1 44.1MHz stream is passed through and played correctly incdicating no resampling by the K-Mixer. When I play the same ac3 stream as audio through XBMC (Babylon - 9.04) I get a stereo (down mixed?) stream at the receiver end.
Has anyone got bit-perfect audio through XBMC? Please let me know. Thanks
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I forgot to mention - I have set the Audio Device as "Envy 24 Family Audio(WDM) .." - my sound card driver. Thanks for your help
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phi2039
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XBMC does not support 44.1k IEC61937 streams (i.e. AC3/DTS over SPDIF). The resampling note was in no way related to this, as encoded ac3/dtc cannot be resampled without first being decoded. 48k streams will be passed-through un-altered.
As an aside, 44.1k AC3/DTS streams are very uncommon for video. It would appear that this content is a DTS Audio CD. Is that the case?
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Phi,
Thanks for your reply. The 44.1Mhz tracks are test tracks available on the internet. Since it is not always easy to figure out if the 44.1Mhz stereo tracks have been resampled or not, the recommended test is to try and see if you can play a 44.1Mhz ac3 (dd or dts) track. If it gets resampled it comes out garbled to the receiver. So basically I was using the 5.1 tracks as test. Are the 44.1Mhz CD tracks (and ripped files) also resampled to 48Mhz by XBMC or does it go through the windows mixer?
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The last sentence was meant for stereo tracks. Are the 44.1Mhz stereo files resampled to 48Mhz
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phi2039
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No. PCM Tracks are no longer re-sampled unless xbmc is specifically configured (via advancedsettings.xml) to do so. Also, in most cases, KMixer is bypassed in favor of hardware mixing. This changes on Vista, as all audio streams are forced to go through MediaFoundation (indirectly via DirectSound). In either case, as long as the hardware supports the stream sample-rate, to re-sampling should occur.
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Got it thanks. Appreciate the clarification phi
