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authorTakashi Iwai <tiwai@suse.de>2012-09-12 16:06:54 (GMT)
committerTakashi Iwai <tiwai@suse.de>2012-09-12 16:13:03 (GMT)
commit7b31d0095e87221dc32c95642a2a714ea08259aa (patch)
tree098dc2c137b0f9a0d098d6e7751ab350e027cd6e /Documentation/sound
parent0afdb8f2869610b7c2eb99d75ba8b9003b8e88d7 (diff)
ALSA: Define more channel map positions
For following the standard, define more channel map positions and shuffle the items a bit: - As both PulseAudio and gstreamer define MONO channel position explicitly, we should follow that, too. The mono streams point to this channel position unless they are explicitly assigned to certain channel positions. - Top-front-* and Top-rear-* positions are added, carried from PulseAudio's definitions. - Move NA and MONO definitions at the top of table right after UNKNOWN, since these are more abstract in comparison with other practical positions. Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'Documentation/sound')
-rw-r--r--Documentation/sound/alsa/Channel-Mapping-API.txt13
1 files changed, 10 insertions, 3 deletions
diff --git a/Documentation/sound/alsa/Channel-Mapping-API.txt b/Documentation/sound/alsa/Channel-Mapping-API.txt
index 4bbf12d..3c43d1a 100644
--- a/Documentation/sound/alsa/Channel-Mapping-API.txt
+++ b/Documentation/sound/alsa/Channel-Mapping-API.txt
@@ -76,8 +76,10 @@ here is a cut:
/* channel positions */
enum {
- /* this follows the alsa-lib mixer channel value + 1 */
SNDRV_CHMAP_UNKNOWN = 0,
+ SNDRV_CHMAP_NA, /* N/A, silent */
+ SNDRV_CHMAP_MONO, /* mono stream */
+ /* this follows the alsa-lib mixer channel value + 3 */
SNDRV_CHMAP_FL, /* front left */
SNDRV_CHMAP_FR, /* front right */
SNDRV_CHMAP_RL, /* rear left */
@@ -98,8 +100,13 @@ enum {
SNDRV_CHMAP_FCH, /* front center high */
SNDRV_CHMAP_FRH, /* front right high */
SNDRV_CHMAP_TC, /* top center */
- SNDRV_CHMAP_NA, /* N/A, silent */
- SNDRV_CHMAP_LAST = SNDRV_CHMAP_NA,
+ SNDRV_CHMAP_TFL, /* top front left */
+ SNDRV_CHMAP_TFR, /* top front right */
+ SNDRV_CHMAP_TFC, /* top front center */
+ SNDRV_CHMAP_TRL, /* top rear left */
+ SNDRV_CHMAP_TRR, /* top rear right */
+ SNDRV_CHMAP_TRC, /* top rear center */
+ SNDRV_CHMAP_LAST = SNDRV_CHMAP_TRC,
};
When a PCM stream can provide more than one channel map, you can

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