AC3 decoding

Discussion in '3-D Audio' started by spellinn, Oct 14, 2003.

  1. spellinn

    spellinn New Member

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    From the latest release notes, kX now supports AC/3 decoding on 10k2-based cards. I have some questions :

    Is this a purely CPU-based decoder, or does it use any of the DSP/hardware features present on the 10k2? Is this the same method as Creative use in their implementation of AC/3 decoding?


    Can it decode AC3 passed to it over the PCI bus (ie from a software DVD player) or AC3 fed into the S/PDIF input? (or both methods?)



    Cheers,


    Neil
     
  2. FieroGT

    FieroGT New Member

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    ya, i would also like to know? i got a sblive 5.1, will it work??????? need it bad!

    thanx

    Rob
     
  3. Max M.

    Max M. h/h member-shmember

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    Lives (10k1 based cards) has following features under kX (today):

    Decoding of ac3 from software player - yes
    Decoding of ac3 from spdif input - no
    Passing ac3 from software player to spdif-out - no
    Passing ac3 from spdif-in to spdif-out - yes

    Audigy X (10k2 based cards):

    Decoding of ac3 from software player - yes
    Decoding of ac3 from spdif input - yes
    Passing ac3 from software player to spdif-out - yes
    Passing ac3 from spdif-in to spdif-out - yes

    ----
    (although some users reported they can't get "Passing ac3 from software player to spdif-out" to work properly)
     
    Last edited: Nov 2, 2003
  4. luterry24

    luterry24 New Member

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    can tell me how to connect them in dsp??
     
  5. Max M.

    Max M. h/h member-shmember

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    you cannot "connect them in dsp" since none of these functions are performed by dsp... you configure them at main kxmixer page instead.
     
  6. HunterZ

    HunterZ New Member

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    How do I configure my DVD software's sound settings and the kX Mixer to decode AC3 in software to send to my 4.1 analog speaker setup? The settings are not self-explanatory enough for me, and I'm sure others would like to know too. Thanks.
     
  7. Lucean

    Lucean New Member

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    I don't have DVD, but I have an avi with AC3 audio. I guess I need a player with 3 outputs, that would send the front stereo output to Wave 4/5, rear stereo output to Wave 6/7 and center+subwoofer to Wave8/9 ...
    I don't know if exists such a player.
    But you can test AC3 with http://www.tfm.ro/ac3/download/test_ac3.rar
     
  8. PITmaster

    PITmaster New Member

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    I do not have any problem with AC3 software decoding with my SBLive but I'm using Vigovsky Alexander's AC3Filter in fact. Every time when I'm playing *.AC3 file or DivX movie with AC3 sound track, the AC3Filter is used by Media Player. Without AC3Filter there's just no AC3 decoding.

    How to decode DD sound track with kX software with SBLive and without AC3Filter?

    PITmaster
     
  9. Eugene Gavrilov

    Eugene Gavrilov kX Project Lead Programmer and Coordinator

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    >> I do not have any problem with AC3 software decoding

    in this case I doubt you really need to test the (more or less) unstable kX code, since the decoding is performed in software, too

    /E
     
  10. HunterZ

    HunterZ New Member

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    Since we're on the topic of AC3Filter, is there a reason why the sound is all scratchy if I set it to 24-bit or 32-bit PCM instead of 16-bit? Does kX not support the higher sample sizes or is it a bug in AC3Filter?
     
  11. Eugene Gavrilov

    Eugene Gavrilov kX Project Lead Programmer and Coordinator

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    kX doesn't support 24-bit audio for regular output devices (such as 'Wave 0/1') -- but it does support 24/96 for 'Wave HQ' (for audigy2 boards)

    (well... the only exception is 24/48 format for audigy1/2 + fxbusx -- search the forum for details)

    if you select 24-bit output, windows (in most cases) will automatically convert the audio data into 16/48 or similar 'compatible' format (software resampling)

    so, in most cases don't select 24-bit (and 32-bit, of course) -- unless you know what you are doing :)
    (since FXBusX requires some additional wires and the audio format should be 'true 24/48'...)

    /Eugene
     
  12. Orestis

    Orestis New Member

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    Guys, could you please prioritize a bit the "Passing ac3 from software player to spdif-out" function on live! cards?

    ...and , when you're done with it, tell the Creative folks how to do it, because they screwed it up (at least under XP) :))
     
  13. dj_stick

    dj_stick Apple Fanboy?

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    no offence to those wanting AC-3 and 3d sound, but the drivers were primarily designed for low latency audio production, only adding on the extra features the card had to offer, so when it comes to priorities, those issues relation to audio production come first
     
  14. daPyr0x

    daPyr0x New Member

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    Okay.....so am I understanding this right?

    If I have my Audigy setup with 5.1 Dolby Digital coming in through the S/PDIF inputs on my card, the kX drivers are now able to decode that?

    I know the Audigy drivers are, but if the kX drivers are, too....all the better....

    Can they? or am I just daydreaming again?
     
  15. Eugene Gavrilov

    Eugene Gavrilov kX Project Lead Programmer and Coordinator

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    yes, kx drivers DO decode incoming spdif signal
    note that the built-in decoder is not perfect -- you may experience BSODs and reboots

    /E
     
    Last edited: Jan 27, 2004
  16. andyvisser

    andyvisser New Member

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    By the sounds of things, ac3 decoding from an external spdif source in an audigy card appears to be pretty sketchy. I was considering upgrading my Live! card to an Audigy 1 (using my current digital i/o addon card) JUST so I could decode my external source. Is the decoding that bad that I should save my money and buy an external hardware decoder (or a higher end soundcard)?
     
  17. trituref

    trituref New Member

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    is there a chance that sblive! support spdif ac3 decode one day or not ? if it's not i think i have to buy an audigy :-(
     
  18. dj_stick

    dj_stick Apple Fanboy?

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    with the AC-3 filter the Live! will decode ac-3
     
  19. daPyr0x

    daPyr0x New Member

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    Sweetness. AC-3 decoding works and it's far better than Creative's AC-3.

    That said, I do have a problem. I'm taking in dolby digital from an external source (it's a custom input from my XBox to what the card thinks is a LiveDrive optical in) and I have a problem with the drivers not getting correct sync with the signal. It was really bad with the creative drivers, because if it couldn't keep up because something ate up cpu cycles of whathaveyou it would stop playback alltogether, whereas the kX driver will continue (choppily) until the cpu is free and then it will catch back on.

    Unfortunately, every once in a while (I do'nt know exactly what is causing it yet) I'll turn on the xbox and as soon as the AC-3 kicks in it will go all choppy like that and be unable to recover. The only way I could make it recover is by shorting the signal and ground pins (Bad tape job meant I could short out the wires at will, which is what I had to do often with the Creative drivers). Is there any way for even a button to just say "re-gain sync" or something with the AC-3 input?

    Also, why is the volume so damn low on it? I see that in the 'issues' thing it says there's no volume control, but it's like really low....any way to help that?
     
  20. stevenz

    stevenz New Member

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    I've got a Soundblaster Live 5.1 (SB0100 - Kx ID's it as SB0102) - as of the current official version (3537?) am I able to input an encoded AC3 stream via an optical daughterboard and have it decode the AC3 to the analog channels with this EMU10K1 chipset? If it's still a bit flaky with the 10k1, could anyone point me towards where I might find the creative drivers that provide this functionality - I've had a hunt but have only managed to find fairly old base drivers. If it works with the AC3Filter utility, any suggestions for configurations in the Kx drivers and/or AC3Filter?

    Thanks for the great work in the Kx drivers guys - much nicer to use than the Creative ones!
     

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