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My pi is plugged to my tv and I have installed mopidy.
Everything is ok, the sound is played through my tv, except that the sound quality is terrible. I mean, it is not listenable at all.
When I play movie the sound is ok.
I have the default settings (alsa, ...) and I don't use a X server, only command lines.
From the Mopidy website:
The Raspberry Pi’s audio quality can be sub-par through the analog output. This is known and unlikely to be fixed as including any higher-quality hardware would increase the cost of the board. If you experience crackling/hissing or skipping audio, you may want to try a USB sound card. Additionally, you could lower your default ALSA sampling rate to 22KHz, though this will lead to a substantial decrease in sound quality.
Many companies have recognized this issue though, and here is one that works quite well. The official forums have had a running discussion on the topic, and here is a link to one of the setup tutorials.
The instructions are below (Note: they were tested with the sound card linked in my answer):
Make the USB card the primary device. Type this in terminal.
sudo nano/etc/modprobe.d/alsa-base.conf
Made the following entries in the file
#options snd-usb-audio index=-2
options snd_bcm2835=-2
exit
reboot
Then, add the following line to the /boot/cmdline.txt
dwc_otg.speed=1
In your home directory create a ~/.libao file in your home directory and enter the following:
driver=alsa
dev=default
Lastly create a ~/.asoundrc in your home directory and enter the following:
Line here to make it so that I don't have to enter tons of code.
pcm.!default {
type asym
playback.pcm "defaultplayback"
capture.pcm "defaultrec"
hint{ show on
description "default play and rec koko"
}
}
pcm.defaultrec {
type plug
slave {
pcm "hw:0,0"
rate 48000
channels 2
format S16_LE
}
hint{ show on
description "default rec koko"
}
}
pcm.defaultplayback{
type rate
slave.pcm mix1
slave.rate 48000
#Intel(R) Core(TM)2 Duo CPU E7500 @ 2.93GHz:
#converter "samplerate_best" # perfect: 16%cpu, maybe overkill
#converter "samplerate_medium" # almost perfect: 6%cpu
#converter "samplerate" # good: 4%cpu, definitely usable
#converter "samplerate_linear" # bad: 2%cpu, way better than default wine resampler
#converter "samplerate_order" # very bad: 2%cpu, like the default wine resampler
converter "samplerate"
hint{ show on
description "default play koko"
}
}
pcm.mix1 {
type dmix
ipc_key 1024
slave {
pcm "hw:0,0"
rate 48000
periods 128
period_time 0
period_size 1024 # must be power of 2
buffer_size 65536
}
}
I had the same problem with Pi MusicBox. I reinstalled everything and the problem was gond. I really don't know what fixed it. It just was gone. You could try to look at the files I changed for musicbox: https://github.com/woutervanwijk/Pi-MusicBox/tree/master/filechanges/etc
The pulseaudio workaround shouldn't be needed if you follow the instructions in http://docs.mopidy.com/en/latest/installation/raspberrypi/#fixing-audio-quality-issues At the time of writing that answer was correct, but with a newer raspi firmware and the right asound settings as mentioned above you should get working sound without pulseaudio.
The only work around I have found is to install pulseaudio and to configure mopidy to use pulseaudio. Now everything works perfectly but I still have no idea about the cause of the problem nor how to fix it using alsa... Linux and the sound, a long sad story...
I've had success using the analogue output by updating the firmware with rpi-update to the latest version and putting the following in ~/.asoundrc:
pcm.!default {
type hw
card 0
}
ctl.!default {
type hw
card 0
}
(Taken from http://www.raspberrypi.org/phpBB3/viewtopic.php?f=66&t=7107)
However, I found that when using HDMI output with this, the first quarter-ish second of each song was skipped. Sometimes it's quite noticeable but it entirely depends on the song.
