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Thread: dts/ac3 passthrough broken?

  1. #1
    Join Date
    Jul 2008
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    Default dts/ac3 passthrough broken?

    My config is an LCD TV connected over HDMI to Gentoo box and Logitech z-5500 ac3/dts decoder connected to TV over optical. Never had problems playing any movies in WinXP.

    Code:
    mplayer dtsmovie.mkv -ao alsa:device=plughw=1.3
    This plays. Only 2 channels and software decoding, right?

    Code:
    mplayer dtsmovie.mkv -ac hwdts -ao alsa:device=plughw=1.3
    This doesn't. What I hear is just varying noise out of speakers.

    Could anyone with working sound-over-hdmi verify this? Could it be that there's something broken inside fglrx?

    TIA.

  2. #2
    Join Date
    Apr 2007
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    Default

    You don't need to specify the device when using -ac hwdts

    I.e. this should work:
    Code:
    mplayer dtsmovie.mkv -ac hwdts
    Last but not least, fglrx code is not involved in sending sound to optical SPDIF. Only mplayer and alsa

    All the best

  3. #3
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    Jul 2008
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    Default

    domi
    The audio is channeled through hdmi, not optical.

  4. #4
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    Apr 2007
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    Default

    Quote Originally Posted by gsmd View Post
    domi
    The audio is channeled through hdmi, not optical.
    Oops, sorry.

    Still, specifying the alsa device when using hwdts (or hwac3) is tricky. For instance, I don't think you can use plughw. Try with just -ao alsa:device=hw=1.3

    HTH

  5. #5
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    Aug 2007
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    Default

    I thought HDMI paththrough never existed?

  6. #6
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    Default

    Quote Originally Posted by Kano View Post
    I thought HDMI paththrough never existed?
    This may depend on HDMI version. I know that HDMI 1.3 is able to carry encoded audio stream (i.e. HD DTS, Dolby true HD ...)

    The answer I gave before are based on my knowledge of mplayer and alsa, but I have no experience with HDMI on Linux (I only have DVI output on my graphical card). So what I say must be taken with a grain of salt.

    HTH

  7. #7
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    Default

    And which HDMI version is supported by the card?

  8. #8
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    domi
    Hey, thanks for your replies. I'll try what you've suggested to see if it makes any difference. But, to tell the truth, I care little about mplayer at the moment, just that it it behaves exactly the way XBMC does: with 'hardware decoding' option set for the audio device in the UI, I get exactly the same noise I get with mplayer.

    Kano
    Gigabyte states it's 1.3.

  9. #9
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    Jul 2008
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    Default

    Well, I know what the problem is: what I'm trying to do is a dumbshit .
    Sending DTS to any TV over HDMI makes no sense at all as TV can't decode it. The DTS receiver connected to TV via optical would receive stereo only. Unfortunately, there's no such thing as digital sound passthrough for TVs (which would definitely make sense).

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