Add support for mono (microphone/speech) recording

[linas]

Most microphones are (still?) mono, so it would be nice to save some disk space, and offer mono (voice) recording at e.g. 22K samples, (or even less) for ordinary voice recording.

Adding this seems almost trivial: just adding to src/media-profiles.c and adding some more pipelines.

On a related note: http://www.speex.org/ says that "The Speex codec has been obsoleted by Opus. It will continue to be available, but since Opus is better than Speex in all aspects, users are encouraged to switch"

http://opus-codec.org/

however, I note that src/media-profiles.c still says "speex" in it, not opus. (oh, and its stereo, which seems like an unlikely choice for voice recording!)

[linas (linasvepstas)]

p.s. the below diff seems to be sufficient for Ubuntu 14.04 (trusty) support:

--- a/src/media-profiles.c
+++ b/src/media-profiles.c
@@ -34,6 +34,8 @@ ProfileRec DefaultProfiles[] = {
  {"voicelossless44","Lossless 44KHz", "wav", "audio/x-raw,rate=44100,chann

  {"voicelossy", "Lossy 32KHz", "spx", "audio/x-raw,rate=32000,chann
+ {"voicelossymono", "Speex Mono Lossy 16KHz", "spx", "audio/x-raw,rate=16000,
+ {"opuslossymono", "Opus Mono Lossy 16KHz", "opus", "audio/x-raw,rate=16000,
 };

 // ! audio/x-raw,rate=44100 ! vorbisenc ! queue ! mux.audio_0