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  1. #1

    Question ALSA and JACK audio server NEED HELP


    Hello. I wish to achieve bitperfect sound play with all multimedia applications on Ubuntu Linux. To achieve that, I think of using ALSA linux sound arcitecture with JACK sound server. Cleary: I wish all application to route sound to the JACK sound server which forwards sound to ALSA and hopfully my sound card gets a bitperfect sound signal this way.

    I have experienced the same goal achieved on a special linux distro called Audiophile Linux. Every application including browsers and multimedia players gave bitperfect signal to the sound card. Only one application was allowed to the sound card by this setting at one time. I wish the same.

    I have ALSA and JACK installed on my Ubuntu Linux but have no idea how to configure them to achieve my goal described above. I have read many documentations but all are greek for me.

    Can anyone help me please with achieving the goal and configuring the system?

    Thank you very very much.
    My name is Vizkeresztpir.

  2. #2
    Linux Guru Segfault's Avatar
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    You have it backwards. ALSA is the low level sound driver. You need it unless you switch to OSS4, which is an alternative to ALSA.
    On ALSA you can run PulseAudio or Jack.
    So first configure your ALSA, make sure it works, and then fire up Jack and go from there. You may want to make sure PulseAudio is not started. Additionally, to get the most out of Jack you need RT (realtime) kernel.

  3. #3
    ALSA works surley, alsaplayer gives a nice bitperfect signal. I removed PulseAudio packages. Installed JACK. But I do not know how to set JACK to be the base sound center for all the apps .

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  6. #5
    I installed JACK 2 with synaptic.
    I created alsa config file and tried to define a new pcm wich uses jack but did not succeed. Here begins the problem.

  7. #6
    Linux Guru Segfault's Avatar
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    Well, something is wrong, then. You really don't think we could come to your place and do it for you, do you? So far you haven't provided anything to help you remotely, using these forums. You may want to click on the link in the footer of my post.

  8. #7
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    i'm not sure why any standard linux audio setup wouldn't be bitperfect?
    all the bits from your audio source make it perfectly all the way to the soundcard.
    you do not need to change anything.

    or maybe you want to clarify?
    clarify why the sound is NOT bitperfect with a standard setup? (i know that commercial OSs tend to "improve" the sound, but not linux)

  9. #8
    Linux Guru Segfault's Avatar
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    Good question. Jack is about sync and low latency, it does not mangle the digital stream any way.

  10. #9
    Quote Originally Posted by Segfault View Post
    Good question. Jack is about sync and low latency, it does not mangle the digital stream any way.
    Bitperfect audio signal means not changed. Standard linux audio system changes audio signal. Its a fact, and hearable.

    Alsaplayer leaves out sound centers, puts not changed signal to the sound card. Quality is ablsolute, and hearable.

    JACK does not change audio signal. Using JACK as sound center result unchanged audio signal. Quality improves compared to standard linux audio setting, it is hearable.

    Using JACK with ALSA results unchanged audio signal.

    It is clear as it is. No more expl. is needed.

  11. #10
    Linux Guru Segfault's Avatar
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    -->
    OK. Lets get it straight.

    When ALSA is used directly then ALSA "changes the signal".
    When ALSA is used over Jack then ALSA does not "change the signal".

    What a nonsense.

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