1 Streaming Audio Over SSH
2 ========================
3 :author: Aaron Ball
4 :email: nullspoon@iohq.net
5
6
7 == {doctitle}
8
9 At home, I have a server/desktop running nearly 24/7
10 (https://archlinux.org[Arch Linux] if anyone is wondering). I use this server
11 for all kinds of experiments. My backups are there (well, it's one of my backup
12 locations). My home dlna server is there. It's also hooked up to my sound
13 system for http://musicpd.org[mpd] so I can have it play my music, controllable
14 by any device on my home wifi. Recently however, I wanted to be able to stream
15 my laptop's audio over my sound system, without having to plug it in directly.
16 The reason being I wanted to stream Spotify over said sound system, but didn't
17 want to go to the hassle of plugging in a keyboard and mouse, and installing a
18 GUI and plugging my server in to a monitor, just so I can occasionally listen
19 to music through not-so-bad speakers. Then I wondered, you can do just about
20 anything with SSH, why not try to stream audio over it. Here's how I do it
21 (there are many other ways).
22
23 [[requirements]]
24 == Requirements
25
26 The server (the computer hooked up to the sound system) needs *mplayer*
27 installed so it'll have something to play the audio with.
28
29 The audio source system (my laptop in this case) needs alsa-utils installed,
30 specifically for the *arecord* application.
31
32 Obviously both the server and the audio source system need ssh installed (and
33 the daemon running on the server).
34
35
36 [[command]]
37 == Command
38
39 Not too much to say here.
40
41 ----
42 arecord -c 1 -r 32000 | ssh <user>@<server> 'mplayer -demuxer rawaudio -rawaudio channels=1:rate=32000:samplesize=1 -nocache -'
43 ----
44
45 So what that command does is...
46
47 arecord::
48 Is a command line program for recording from audio devices. If no output file
49 is specified (like in this case), it writes what it records to stdout. For
50 our purposes, we pipe stdout to ssh in the next command.
51
52 ssh...mplayer::
53 Here we send stdout from the previous command (hence the pipe) straight to
54 the server over ssh. Mplayer on the server plays what it receives from stdin
55 (the final - ). The rest of the mplayer flags are just for audio quality
56 control (same for the flags on arecord). The -nocache reduces delay a bit,
57 but in some cases can cause skipping, so you might want to remove that
58 switch.
59
60
61 There is one caveat to this. While it works fine for streaming internet radio
62 or any other audio you want really, streaming audio for a video source doesn't
63 work nearly as well. On my setup, there is about a .75 second delay, so YouTube
64 videos don't sync up. Otherwise though this works swimmingly.
65
66
67 Category:Linux
68 Category:SSH
69
70
71 // vim: set syntax=asciidoc:
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