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FearlessSpiff
n00b
Joined: 26 Sep 2004
Posts: 69
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 Posted: Tue Oct 10, 2006 1:56 pm Post subject: [Solved] Alsa SPDIF volume control of analog sound |
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Hi
I managed to get sound output on my SPDIF for AC3 *and* normal analog sound. Now it is clear to me, that i cannot control the volume of an AC3 stream, but it should be possible with all others (i.e. mp3 sound...). At least it is in Winblows. What should i do? I tried every mixersetting in alsamixer but nothing seems to change the volume of the sound...
Thanks
Last edited by FearlessSpiff on Mon Oct 16, 2006 2:28 pm; edited 1 time in total |
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FishB8
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Joined: 17 Mar 2003
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| Posted: Tue Oct 10, 2006 10:43 pm Post subject: |
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There is SPDIF data mode (this is what AC3 uses) and there is SPDIF audio mode (what most everything else uses). Neither is analog, both are digital, and hence neither have volume control, at least not within the sound card.
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"...as we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours, and this we should do freely and generously." -Benjamin Franklin |
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FearlessSpiff
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Joined: 26 Sep 2004
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| Posted: Wed Oct 11, 2006 6:51 am Post subject: |
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Ahh, but then why when adjusting the volume in mplayer or xine or mythtv nothing happens?
And: Is the alsamixer only adjusting volumes on the card or is this software based? In fact: Why does this work in Windows? What is the difference between the mixer in Windows and in Linux?
I am sure it should be possible to somehow adjust the audio mode of SPDIF on Linux, just trying to figure out how... |
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FishB8
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| Posted: Sat Oct 14, 2006 2:45 am Post subject: |
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| Quote: | | Ahh, but then why when adjusting the volume in mplayer or xine or mythtv nothing happens? |
Uh... thats what I just said would happen.
| Quote: | And: Is the alsamixer only adjusting volumes on the card or is this software based? In fact: Why does this work in Windows? What is the difference between the mixer in Windows and in Linux?
I am sure it should be possible to somehow adjust the audio mode of SPDIF on Linux, just trying to figure out how... |
With windows, anything could be happening. It totally depends on what was programmed into the interface. Alsa only deals with hardware, except for the alsa plugins of course. So it is only adjusting volumes on the card, which in turn has no effect on digital outputs. Attenuators only work on analoge output. Yes it is possible to have volume control on digital signals, but I've never seen that on a consumer audio card. The reason is because if you have a digital output, it will be sent to an external device with a DAC somewhere and that is where you set the volume.
Some media players try to use the hardware volume control while other media players use a software volume control (VLC for instance). In the case of a digital output, only the media players using a software based volume control would have any effect.
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"...as we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours, and this we should do freely and generously." -Benjamin Franklin |
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FearlessSpiff
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| Posted: Sun Oct 15, 2006 4:50 pm Post subject: |
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I helped myself and bought an analog cable for stereo output...  So now everything is working, thanks. |
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