Comment 16 for bug 1286021

pulseaudio assume surround21 is four channels since buffer time is half of stereo

why alsa lib surround21 did not specity any channel ?

http://git.alsa-project.org/?p=alsa-lib.git;a=commitdiff;h=48f1b308cc66152eb6db66742dd0d08d888cda8d;hp=5c4cd46810cef8850b037fca9e38ffd43b0bff22

2.1 speaker set is different from 5.1 speaker set

070| 0.000) D: [pulseaudio] alsa-util.c: Trying front:0 with SND_PCM_NO_AUTO_FORMAT ...
( 0.071| 0.000) D: [pulseaudio] alsa-util.c: Managed to open front:0
( 0.071| 0.000) D: [pulseaudio] alsa-util.c: Maximum hw buffer size is 371 ms
( 0.071| 0.000) D: [pulseaudio] alsa-util.c: Set buffer size first (to 3528 samples), period size second (to 441 samples).
( 0.071| 0.000) D: [pulseaudio] alsa-mixer.c: Profile output:analog-stereo+input:analog-stereo supported.
( 0.071| 0.000) D: [pulseaudio] alsa-mixer.c: Skipping profile output:analog-stereo+input:iec958-stereo - will not be able to open input:iec958-stereo
( 0.071| 0.000) D: [pulseaudio] alsa-mixer.c: Looking at profile output:analog-surround-21
( 0.071| 0.000) D: [pulseaudio] alsa-mixer.c: Checking for playback on Analog Surround 2.1 (analog-surround-21)
( 0.071| 0.000) D: [pulseaudio] alsa-util.c: Trying surround21:0 with SND_PCM_NO_AUTO_FORMAT ...
( 0.072| 0.000) D: [pulseaudio] alsa-util.c: Managed to open surround21:0
( 0.072| 0.000) D: [pulseaudio] alsa-util.c: Maximum hw buffer size is 185 ms
( 0.094| 0.021) D: [pulseaudio] alsa-util.c: Set buffer size first (to 3528 samples), period size second (to 441 samples).
( 0.094| 0.000) D: [pulseaudio] alsa-mixer.c: Profile output:analog-surround-21 supported.