LinuxQuestions.org - [SOLVED] HDMI loud and distorted. Any suggestions?

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HDMI loud and distorted. Any suggestions?

I have Slackware-Current (09/2014) on an I3 based Samsung NP350 with Panther Point chipset. Alsa is installed & configured for sound, although pulseaudio is installed (but not used) because I needed it for some compile and it seems like a major PITA to configure.

lspci & aplay-l are as follows

Code:

00:1b.0 Audio device: Intel Corporation 7 Series/C210 Series Chipset Family High Definition Audio Controller (rev 04)

bash-4.3$ aplay -l

**** List of PLAYBACK Hardware Devices ****

card 0: PCH [HDA Intel PCH], device 0: ALC269VC Analog [ALC269VC Analog]

  Subdevices: 1/1

  Subdevice #0: subdevice #0

card 0: PCH [HDA Intel PCH], device 3: HDMI 0 [HDMI 0]

  Subdevices: 1/1

  Subdevice #0: subdevice #0

Sound defaults to the speakers/earphone. As aplay shows, it's all card0, device 0 is speakers/earphone, device 3 is hdmi. My first attempt at this was simply use an ~/.asoundrc which made device 3 the default. HDMI was too loud and distorted horribly.
Second attempt was the enclosed ~/.asoundrc,

Code:

  pcm.hdmi_hw {

            type hw

            card 0

            device 3

    }

    ctl.!hdmi_hw {

            type hw

            card 0

            device 3

    }

    pcm.!default {

            type plug

            slave.pcm "softvol"

    }

    pcm.softvol {

            type softvol

            slave {

                    pcm "dmix"

            }

            control {

                    name "Pre-Amp"

                    card 0

            }

            min_dB -20.0

            max_dB 0.0

            resolution 11

    }

which google found for me and gives me a hdmi volume control in alsamixer, but still has the distortion. Here is a sample
https://onedrive.live.com/?cid=99361...4096FF2C07!208
You want the file: Voice\ 010.m4a
Sorry about the weird file type - it was recorded on a phone. mplayer handles it without issue.

Any ideas here? The sample has a low backing music and commentary. The sound reminds me of an over driven device - probably an input. I can get it down to reasonable levels at the output, but that's not good enough, it seems.

EDIT: Just noticed that muting the S/PDIF in alsamixer kills the sound in hdmi. If I could CONTROL that, then I might get somewhere. But alsamixer shows no control for that. Just some little mute box.

You almost certainly need a rate convert to take everything to 48K and you probably need to change the buffering, that has been my experience. S/PDIF is an binary thing not sure what you mean by control that.

Try this:

Code:

pcm.hdmi_hw {

  type hw

  card 0    # <--- card number

  device 3  # <--- device number

}



pcm.dmixer {

        type dmix

        ipc_key 1024

        slave {

        pcm "hdmi_hw"

        buffer_size 32768

        rate 48000

        period_time 0

        period_size 1024

        buffer_time 0

        }} 



pcm.rate_convert {

        type plug

        slave { pcm "dmixer" 

              }

}



pcm.hdmi_complete {

  type softvol

  slave { pcm "rate_convert" } 

  control.name "Master"

  control.card 0

}



pcm.null_capture {

  type null

}



pcm.!default {

  type asym

  playback.pcm {

    type plug

    slave { pcm "hdmi_complete" }

  }

  capture.pcm {

    type plug

    slave { pcm "null_capture" }

  }

}

do you really have to create a ~/.asoundrc to get the output via HDMI ?
is there no way to switch dynamically?

Quote:

Originally Posted by a4z (Post 5328717)

is there no way to switch dynamically?

I've heard of some udev rules that would help you doing that with vanilla Alsa, but I can't find it right now. :(

Either way, dynamic sound switching is one of the reasons that led Lennart to create PulseAudio.

@chemfire: That ~/.asoundrc looks a piece of genius. resampling makes sense. I will try that.

I think (repeat think) that the hdmi plug can be sensed, and so if I define it correctly, it doesn't see a hdmi output unless one is there. This whole area is so poorly defined that I'm prepared to fiddle with an asoundrc for the few times I want hdmi.

/takes hat off

@chemfire: That ~/.asoundrc does the trick - I get clear loud but undistorted hdmi sound, and I think I have a volume control for it due to the bits in my asound.state.

The one thing I lack is plug-ability on the hdmi. If I pull the hdmi, the sound still goes to the hdmi until I remove the asoundrc. I can move it out of the way, because I use hdmi rarely.

Thanks for that