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Author Topic: Feature Request: Bitperfect playback profile  (Read 1789 times)

dmm

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Feature Request: Bitperfect playback profile
« on: September 01, 2011, 03:44:07 pm »

I have started and contributed to many a thread on getting bitperfect playback to work in MC16.  The problem is that there are many reasons for bitperfect playback to fail.  From hardware, operating system and in MC16 itself.

It would be great if jriver would implement a setting within MC that a user could select that would force all of the MC16 settings that impact bitperfect playback to the correct settings so that we could at least then just focus on the hardware and OS layer issues to getting it to work.

For instance, MC16 "bitperfect" button could set the volume to max, DSP enhancements to off, gapped playback and transitions, all audio conversions to off on server and client, etc, etc.

Often the suggestion is made to just let MC16 decode the AC3 and DTS files and forget about bitperfect playback.  That is not an ideal solution for many since the DACs in some of our receivers, transports or external DAC's exceed the performance of the DAC's in our PC sound cards.

In my personal case, I use a Class-D amplifier that keeps all of the sound in the digital domain till the last step before speaker amplification.  So I don't want to use the analog outputs of my PC because that would introduce an extra step converting the sound back to digital and then back to analog.  Causing a noticeable sound degradation.
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mojave

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Re: Feature Request: Bitperfect playback profile
« Reply #1 on: September 01, 2011, 03:56:54 pm »

Often the suggestion is made to just let MC16 decode the AC3 and DTS files and forget about bitperfect playback.  That is not an ideal solution for many since the DACs in some of our receivers, transports or external DAC's exceed the performance of the DAC's in our PC sound cards.
Decoding and where the digital to analog conversion take place are two separate issues. You can decode on the HTPC, but send it via digital PCM through an HDMI cable to the receiver. 

Quote
In my personal case, I use a Class-D amplifier that keeps all of the sound in the digital domain till the last step before speaker amplification.  So I don't want to use the analog outputs of my PC because that would introduce an extra step converting the sound back to digital and then back to analog.  Causing a noticeable sound degradation.

All of my Class D amps are analog. None of them have a digital input. They wouldn't unless they were integrated into a receiver. What amps do you have?
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Matt

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Re: Feature Request: Bitperfect playback profile
« Reply #2 on: September 01, 2011, 04:07:47 pm »

mojave is exactly right.

You can output PCM as a bit-perfect S/PDIF stream (up to 2 channels) or a bit-perfect HDMI stream (many channels).  Either of these allow using an external DAC.

Decoding is a different issue.  Media Center doesn't really support outboard decoding for audio playback (i.e. MP3 bitstreaming), and I can't think of a good argument for this.  Perhaps users with S/PDIF only that played a DTS or AC3 audio file might want it, but this is a bit of a corner case to justify the complexity in my opinion.
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Matt Ashland, JRiver Media Center

dmm

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Re: Feature Request: Bitperfect playback profile
« Reply #3 on: September 01, 2011, 04:58:43 pm »


 
All of my Class D amps are analog. None of them have a digital input. They wouldn't unless they were integrated into a receiver. What amps do you have?

I have a panasonic BX500 receiver which uses a TI chipset equibit amp.
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dmm

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Re: Feature Request: Bitperfect playback profile
« Reply #4 on: September 01, 2011, 05:04:59 pm »

mojave is exactly right.

You can output PCM as a bit-perfect S/PDIF stream (up to 2 channels) or a bit-perfect HDMI stream (many channels).  Either of these allow using an external DAC.

Decoding is a different issue.  Media Center doesn't really support outboard decoding for audio playback (i.e. MP3 bitstreaming), and I can't think of a good argument for this.  Perhaps users with S/PDIF only that played a DTS or AC3 audio file might want it, but this is a bit of a corner case to justify the complexity in my opinion.

I must be "a corner case"...because I use a firestone audio bravo digital transport which brings SPDIF jitter down to an ultra low 50ps and is based on the following chipsets: USB Chip : TENOR - TE0722, Receiver Chip : TI - DIR9001, Transmitter Chip : Wolfson - WM8804.  The sound is far more pleasing then what I get out of my HDMI of my HTPC.  I routinely play CD DTS files and prefer to keep all of my files outputting bitperfect so that my Panasonic BX500 digital receiver can do all of the decoding.

I accept that I may have misspoken about my desire for bitperfect in my original post and accept that what I am really asking for is for MC16 to not "decode" the audio stream but instead pass it unmolested to my receiver for decoding.  I would still like some sort of button that would allow me to thru MC into a bitperfect mode.
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Matt

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Re: Feature Request: Bitperfect playback profile
« Reply #5 on: September 01, 2011, 05:39:17 pm »

I must be "a corner case"...because I use a firestone audio bravo digital transport which brings SPDIF jitter down to an ultra low 50ps and is based on the following chipsets: USB Chip : TENOR - TE0722, Receiver Chip : TI - DIR9001, Transmitter Chip : Wolfson - WM8804.  The sound is far more pleasing then what I get out of my HDMI of my HTPC.  I routinely play CD DTS files and prefer to keep all of my files outputting bitperfect so that my Panasonic BX500 digital receiver can do all of the decoding.

I accept that I may have misspoken about my desire for bitperfect in my original post and accept that what I am really asking for is for MC16 to not "decode" the audio stream but instead pass it unmolested to my receiver for decoding.  I would still like some sort of button that would allow me to thru MC into a bitperfect mode.

I think we have two ideas in play here.

One is the ability to bitstream audio, like is possible for video.  This could be useful for S/PDIF users that play DTS audio with more than 2 channels (PCM over S/PDIF would be bit perfect for 2.0 DTS) and use an outboard decoder.  This might be a nice enhancement for a future version if enough users want it.

The other is some sort of switch that disables any audio processing, like volume, cross-fades, etc.  I'm less clear on what this would be used for, although I'm not opposed to it.  You could probably achieve mostly the same thing today by creating two (or more) zones and configuring them independently.
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Matt Ashland, JRiver Media Center
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