ALSA: PCM: channel mapping API implementation
This patch implements the basic data types for the standard channel
mapping API handling.
- The definitions of the channel positions and the new TLV types are
added in sound/asound.h and sound/tlv.h, so that they can be
referred from user-space.
- Introduced a new helper function snd_pcm_add_chmap_ctls() to create
control elements representing the channel maps for each PCM
(sub)stream.
- Some standard pre-defined channel maps are provided for
convenience.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index cdca2ab..669c85a 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -437,6 +437,7 @@
struct snd_info_entry *proc_xrun_debug_entry;
#endif
#endif
+ struct snd_kcontrol *chmap_kctl; /* channel-mapping controls */
};
struct snd_pcm {
@@ -1086,4 +1087,51 @@
return "Capture";
}
+/*
+ * PCM channel-mapping control API
+ */
+/* array element of channel maps */
+struct snd_pcm_chmap_elem {
+ unsigned char channels;
+ unsigned char map[15];
+};
+
+/* channel map information; retrieved via snd_kcontrol_chip() */
+struct snd_pcm_chmap {
+ struct snd_pcm *pcm; /* assigned PCM instance */
+ int stream; /* PLAYBACK or CAPTURE */
+ struct snd_kcontrol *kctl;
+ const struct snd_pcm_chmap_elem *chmap;
+ unsigned int max_channels;
+ unsigned int channel_mask; /* optional: active channels bitmask */
+ void *private_data; /* optional: private data pointer */
+};
+
+/* get the PCM substream assigned to the given chmap info */
+static inline struct snd_pcm_substream *
+snd_pcm_chmap_substream(struct snd_pcm_chmap *info, unsigned int idx)
+{
+ struct snd_pcm_substream *s;
+ for (s = info->pcm->streams[info->stream].substream; s; s = s->next)
+ if (s->number == idx)
+ return s;
+ return NULL;
+}
+
+/* ALSA-standard channel maps (RL/RR prior to C/LFE) */
+extern const struct snd_pcm_chmap_elem snd_pcm_std_chmaps[];
+/* Other world's standard channel maps (C/LFE prior to RL/RR) */
+extern const struct snd_pcm_chmap_elem snd_pcm_alt_chmaps[];
+
+/* bit masks to be passed to snd_pcm_chmap.channel_mask field */
+#define SND_PCM_CHMAP_MASK_24 ((1U << 2) | (1U << 4))
+#define SND_PCM_CHMAP_MASK_246 (SND_PCM_CHMAP_MASK_24 | (1U << 6))
+#define SND_PCM_CHMAP_MASK_2468 (SND_PCM_CHMAP_MASK_246 | (1U << 8))
+
+int snd_pcm_add_chmap_ctls(struct snd_pcm *pcm, int stream,
+ const struct snd_pcm_chmap_elem *chmap,
+ int max_channels,
+ unsigned long private_value,
+ struct snd_pcm_chmap **info_ret);
+
#endif /* __SOUND_PCM_H */