Add volume range setting

[chukysoria]

Add a volume range setting -- useful for the Raspberry Pi's built-in DAC

[chukysoria]

Fixes #22

[oschwede]

When I'm using --dbrange, a segfault happens when trying to access the webinterface. The funny thing is, when turning on debugging by using -d switch, the segfault does not happen anymore.

I'm running on Arch Linux, pyalsaaudio is 0.8.2. Any ideas what could cause this problem?

[maumi]

Try to comment out
Print zerovars
in connect.py

[oschwede]

Thanks for your help :) After uncommenting it runs fine.

But I'm still wondering, why this issues appears when using --dbrange option, because non of the changes in this pull request affect the zeroconf code. When I have some time, I will try to investigate that.

[Fornoth]

@chukysoria Pull request looks good, except can you change the option to represent it better, maybe something like --min-vol-range?
@oschwede if you can come to the gitter channel I can help you debug that (if you wanna get started, try running it like LD_LIBRARY_PATH=$PWD python -m trace -t --ignore-dir venv --ignore-dir /usr main.py)

[EyMaddis]

any updates?

[Fornoth]

I'll try merging this in the next week or two

[oschwede]

I tried to debug the segfault today, but I cannot reproduce it anymore. Not even with the code from beginning of march. When I checkout this particular pull request with "git fetch origin pull/34/head:test && git checkout test", everythings is fine.

Avahi has been installed on my computer a few weeks ago, maybe that makes a difference? Although uninstalling Avahi does not bring back the segfault.