Unable to configure a mixer_control with a whitespace at it send

[mimmus]

Bug report

Describe the bug

Unfortunately, my DAC has these controls:

$ amixer --card 3 scontents
Simple mixer control 'MISSION USB Audio 2.0 ',0
  Capabilities: pvolume pswitch
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 127
  Mono:
  Front Left: Playback 127 [100%] [0.00dB] [on]
  Front Right: Playback 127 [100%] [0.00dB] [on]
Simple mixer control 'MISSION USB Audio 2.0 ',1
  Capabilities: pvolume pvolume-joined pswitch pswitch-joined
  Playback channels: Mono
  Limits: Playback 0 - 127
  Mono: Playback 127 [100%] [0.00dB] [on]

As you can see, there is an extra whitespace at the end of control name. Specifying: mixer_control "MISSION USB Audio 2.0 " in mpd.conf dosn't work, neither mixer_control "MISSION USB Audio 2.0\ " or any other trick.

Expected Behavior

A mixer-control with whitespace at its end should be supported as it's quite common, probably due to ALSA pitfalls.

Actual Behavior

mixer_control not recognized

Version

 $ mpd --version
Music Player Daemon 0.23.12 (0.23.12)
Copyright 2003-2007 Warren Dukes <warren.dukes@gmail.com>
Copyright 2008-2021 Max Kellermann <max.kellermann@gmail.com>
This is free software; see the source for copying conditions.  There is NO
warranty; not even MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Database plugins:
 simple proxy upnp

Storage plugins:
 local smbclient udisks nfs curl

Neighbor plugins:
 smbclient upnp udisks

Decoders plugins:
 [mad] mp3 mp2
 [mpg123] mp3
 [vorbis] ogg oga
 [oggflac] ogg oga
 [flac] flac
 [opus] opus ogg oga
 [sndfile] wav aiff aif au snd paf iff svx sf voc w64 pvf xi htk caf sd2
 [dsdiff] dff
 [dsf] dsf
 [hybrid_dsd] m4a
 [faad] aac
 [mpcdec] mpc
 [wavpack] wv
 [openmpt] mptm mod s3m xm it 669 amf ams c67 dbm digi dmf dsm dtm far imf ice j2b m15 mdl med mms mt2 mtm nst okt plm psm pt36 ptm sfx sfx2 st26 stk stm stp ult wow gdm mo3 oxm umx xpk ppm mmcmp
 [modplug] 669 amf ams dbm dfm dsm far it med mdl mod mtm mt2 okt s3m stm ult umx xm
 [mikmod] amf dsm far gdm imf it med mod mtm s3m stm stx ult uni xm
 [sidplay] sid mus str prg P00
 [wildmidi] mid
 [fluidsynth] mid
 [adplug] amd d00 hsc laa rad raw sa2
 [ffmpeg] 16sv 3g2 3gp 4xm 8svx aa3 aac ac3 adx afc aif aifc aiff al alaw amr anim apc ape asf atrac au aud avi avm2 avs bap bfi c93 cak cin cmv cpk daud dct divx dts dv dvd dxa eac3 film flac flc fli fll flx flv g726 gsm gxf iss m1v m2v m2t m2ts m4a m4b m4v mad mj2 mjpeg mjpg mka mkv mlp mm mmf mov mp+ mp1 mp2 mp3 mp4 mpc mpeg mpg mpga mpp mpu mve mvi mxf nc nsv nut nuv oga ogm ogv ogx oma ogg omg opus psp pva qcp qt r3d ra ram rl2 rm rmvb roq rpl rvc shn smk snd sol son spx str swf tak tgi tgq tgv thp ts tsp tta xa xvid uv uv2 vb vid vob voc vp6 vmd wav webm wma wmv wsaud wsvga wv wve rtp:// rtsp:// rtsps://
 [gme] ay gbs gym hes kss nsf nsfe rsn sap spc vgm vgz
 [pcm]

Filters:
 libsamplerate soxr

Tag plugins:
 id3tag

Output plugins:
 shout null fifo sndio pipe alsa ao oss openal pipewire pulse jack httpd snapcast recorder

Encoder plugins:
 null vorbis opus lame wave flac

Archive plugins:
 [bz2] bz2
 [zzip] zip
 [iso] iso

Input plugins:
 file io_uring archive alsa curl ffmpeg smbclient nfs mms cdio_paranoia

Playlist plugins:
 extm3u m3u pls xspf asx rss soundcloud flac cue embcue

Protocols:
 file:// alsa:// cdda:// ftp:// ftps:// gopher:// hls+http:// hls+https:// http:// https:// mms:// mmsh:// mmst:// mmsu:// nfs:// rtmp:// rtmpe:// rtmps:// rtmpt:// rtmpte:// rtmpts:// rtp:// rtsp:// rtsps:// scp:// sftp:// smb:// srtp://

Other features:
 avahi dbus udisks epoll icu inotify ipv6 systemd tcp un

Configuration

...
audio_output {
        type "alsa"
        name "MISSION USB Audio 2.0"
        device "hw:3,0" # customize for your DAC; run aplay -l to find yours
        # DoP
        dsd_usb "no"
        dop "no"
        buffer_time "200000"
        period_time "5084"
        auto_resample "no" # otherwise, ALSA will convert everything to PCM
        auto_channels "no"
        auto_format "no"
        # Don't enable DoP unless you know you need it. Look in your DAC's manual.
        # dop "yes"
        replay_gain_handler "none"
        mixer_type "hardware"
        mixer_control "MISSION USB Audio 2.0 "
        mixer_index "0"
}
...

Log

mixer: Failed to read mixer for "MISSION USB Audio 2.0": no such mixer control: MISSION USB Audio 2.0

[borine]

:sigh: this is a repeat of https://github.com/MusicPlayerDaemon/MPD/issues/374#issuecomment-2208380566

In reply to that I said:

you need to make sure you use the correct mixer_device parameter

Now it is clear that you have not set that parameter at all.

So this issue has nothing to do with "white space". You just need to include

mixer_device "hw:3"

[mimmus]

Sorry to bother you with cross-posting. I’m trying to set up native DSD with this integrated amplifier without vendor support, starting from needed USB quirks in the Linux kernel… Actually, I was able to see it as DSD-capable DAC but DSD file plays with a strange noise in background and I’m investigating volume settings.

I will re-try when at pc again. Thanks.

[mimmus]

I missed: mixer_device "hw:3" Unfortunately, HW volume control doesn't help with my original issue (noise in the background of DSD files) but this is another issue.

Sorry and thanks for support.