Only getting noise output

[m-hearn]

client and server are connected, tested with /dev/urandom.

mopidy config is writing to /tmp/snapfifo, but only delivering noise.

starting and stopping the server audio in mopidy does start/stop noise at client end.

local client (on same server as mopidy) also produces the same issue.

[running on Pi2 server and PiB on client]

• tried upgrading to dev instance of mopidy - from 1.1.1 - no improvement

[badaix]

Hi,
what version of snapcast are you using? Any specific release? Master or develop branch?
Can you try to directly feed in a live radio station without any Mopidy or MPD:
In a root shell (sudo su) on the server Pi do:
wget -q -O - http://1live.akacast.akamaistream.net/7/706/119434/v1/gnl.akacast.akamaistream.net/1live |mpg123 -w - - > /tmp/snapfifo
You might need to install mpg123 (sudo apt-get install mpg123).

[bcm0]

Hi,
when I directly launch gst-launch-0.10 (which is used by mopidy) and pipe a musicfile to /tmp/snapfifo I only hear noise, but using gst-launch-1.0 fixes the problem.
Hopefully mopidy will switch to gstreamer-1.0 in the near future.

gst-launch-0.10 filesrc location=~/sample.mp3 ! decodebin ! audioconvert ! audioresample ! filesink location=/tmp/snapfifo

gst-launch-1.0 filesrc location=~/sample.mp3 ! decodebin ! audioconvert ! audioresample ! filesink location=/tmp/snapfifo

[maosuyun2009]

Hi,
I have a wav file, I want to know, When I Test with command like "cat 123.wav > /tmp/snapfifo", I only get noise, I think snapclient just read pcm data from snapfifo, when i try to cat 123.wav to snapfifo, why can't play it?

[Lakritzator]

@maosuyun2009 this is a different thing as the initial ticket was created for.

You are mixing up PCM, a digital representation of audio, with WAV as a file format.
A WAV file (https://en.wikipedia.org/wiki/WAV) can contain PCM, but is not necessary
PCM.

It also would be very inefficient to have uncompressed audio in a WAV file, so currently a lot of them are compressed. And PCM is not compressed audio data!

Even if you have PCM in the WAV, you still have a header and this might cause horrible noise.

In short PCM != WAV!

[maosuyun2009]

@Lakritzator Thanks, In oss architechture, i always cat wav file to /dev/oss, so I just think i can do it like oss

[badaix]

@maosuyun2009 actually for "normal" (containing PCM data) WAV-files cat will work. A requirement for the cat method is that the wave header size is a multiple of 4 (usually it's 44 bytes). Otherwise left/right and upper/lower bytes are mixed up and cause noisy audio.

[prospo]

Found a solution. Working on Ubuntu 15.10 (Wili Werewolf), mopidy 2.0.0-1 (jessie), snapcast (git-master) with standard gst-launch-1.0

From my /etc/mopidy/mopidy.conf in the audio section:
[audio]
audioresample ! audioconvert ! audio/x-raw,rate=44100,channels=2,format=S16LE ! wavenc ! filesink location=/tmp/snapfifo

edit: changed the output string, it didn't play well between 48KHz and 44.1KHz input.

[badaix]

added this to the Readme.md (3a4bfbd)