big s/polyp/pulse/g

git-svn-id: file:///home/lennart/svn/public/pulseaudio/trunk@1033 fefdeb5f-60dc-0310-8127-8f9354f1896f

src/pulse/volume.h

@@ -0,0 +1,172 @@
+#ifndef foovolumehfoo
+#define foovolumehfoo
+
+/* $Id$ */
+
+/***
+  This file is part of PulseAudio.
+ 
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as published
+  by the Free Software Foundation; either version 2 of the License,
+  or (at your option) any later version.
+ 
+  PulseAudio is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  General Public License for more details.
+ 
+  You should have received a copy of the GNU Lesser General Public License
+  along with PulseAudio; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#include <inttypes.h>
+#include <pulse/cdecl.h>
+#include <pulse/sample.h>
+
+/** \page volume Volume Control
+ *
+ * \section overv_sec Overview
+ *
+ * Sinks, sources, sink inputs and samples can all have their own volumes.
+ * To deal with these, The Polypaudio libray contains a number of functions
+ * that ease handling.
+ *
+ * The basic volume type in Polypaudio is the \ref pa_volume_t type. Most of
+ * the time, applications will use the aggregated pa_cvolume structure that
+ * can store the volume of all channels at once.
+ *
+ * Volumes commonly span between muted (0%), and normal (100%). It is possible
+ * to set volumes to higher than 100%, but clipping might occur.
+ *
+ * \section calc_sec Calculations
+ *
+ * The volumes in Polypaudio are logarithmic in nature and applications
+ * shouldn't perform calculations with them directly. Instead, they should
+ * be converted to and from either dB or a linear scale:
+ *
+ * \li dB - pa_sw_volume_from_dB() / pa_sw_volume_to_dB()
+ * \li Linear - pa_sw_volume_from_linear() / pa_sw_volume_to_linear()
+ *
+ * For simple multiplication, pa_sw_volume_multiply() and
+ * pa_sw_cvolume_multiply() can be used.
+ *
+ * Calculations can only be reliably performed on software volumes
+ * as it is commonly unknown what scale hardware volumes relate to.
+ *
+ * The functions described above are only valid when used with
+ * software volumes. Hence it is usually a better idea to treat all
+ * volume values as opaque with a range from PA_VOLUME_MUTE (0%) to
+ * PA_VOLUME_NORM (100%) and to refrain from any calculations with
+ * them.
+ *
+ * \section conv_sec Convenience Functions
+ *
+ * To handle the pa_cvolume structure, the Polypaudio library provides a
+ * number of convenienc functions:
+ *
+ * \li pa_cvolume_valid() - Tests if a pa_cvolume structure is valid.
+ * \li pa_cvolume_equal() - Tests if two pa_cvolume structures are identical.
+ * \li pa_cvolume_channels_equal_to() - Tests if all channels of a pa_cvolume
+ *                             structure have a given volume.
+ * \li pa_cvolume_is_muted() - Tests if all channels of a pa_cvolume
+ *                             structure are muted.
+ * \li pa_cvolume_is_norm() - Tests if all channels of a pa_cvolume structure
+ *                            are at a normal volume.
+ * \li pa_cvolume_set() - Set all channels of a pa_cvolume structure to a
+ *                        certain volume.
+ * \li pa_cvolume_reset() - Set all channels of a pa_cvolume structure to a
+ *                          normal volume.
+ * \li pa_cvolume_mute() - Set all channels of a pa_cvolume structure to a
+ *                         muted volume.
+ * \li pa_cvolume_avg() - Return the average volume of all channels.
+ * \li pa_cvolume_snprint() - Pretty print a pa_cvolume structure.
+ */
+
+/** \file
+ * Constants and routines for volume handling */
+
+PA_C_DECL_BEGIN
+
+/** Volume specification:
+ *  PA_VOLUME_MUTED: silence;
+ * < PA_VOLUME_NORM: decreased volume;
+ *   PA_VOLUME_NORM: normal volume;
+ * > PA_VOLUME_NORM: increased volume */
+typedef uint32_t pa_volume_t;
+
+/** Normal volume (100%) */
+#define PA_VOLUME_NORM (0x10000)
+
+/** Muted volume (0%) */
+#define PA_VOLUME_MUTED (0)
+
+/** A structure encapsulating a per-channel volume */
+typedef struct pa_cvolume {
+    uint8_t channels;                     /**< Number of channels */
+    pa_volume_t values[PA_CHANNELS_MAX];  /**< Per-channel volume  */
+} pa_cvolume;
+
+/** Return non-zero when *a == *b */
+int pa_cvolume_equal(const pa_cvolume *a, const pa_cvolume *b);
+
+/** Set the volume of all channels to PA_VOLUME_NORM */
+#define pa_cvolume_reset(a, n) pa_cvolume_set((a), (n), PA_VOLUME_NORM)
+
+/** Set the volume of all channels to PA_VOLUME_MUTED */
+#define pa_cvolume_mute(a, n) pa_cvolume_set((a), (n), PA_VOLUME_MUTED)
+
+/** Set the volume of all channels to the specified parameter */
+pa_cvolume* pa_cvolume_set(pa_cvolume *a, unsigned channels, pa_volume_t v);
+
+/** Maximum length of the strings returned by pa_cvolume_snprint() */
+#define PA_CVOLUME_SNPRINT_MAX 64
+
+/** Pretty print a volume structure */
+char *pa_cvolume_snprint(char *s, size_t l, const pa_cvolume *c);
+
+/** Return the average volume of all channels */
+pa_volume_t pa_cvolume_avg(const pa_cvolume *a);
+
+/** Return TRUE when the passed cvolume structure is valid, FALSE otherwise */
+int pa_cvolume_valid(const pa_cvolume *v);
+
+/** Return non-zero if the volume of all channels is equal to the specified value */
+int pa_cvolume_channels_equal_to(const pa_cvolume *a, pa_volume_t v);
+
+/** Return 1 if the specified volume has all channels muted */
+#define pa_cvolume_is_muted(a) pa_cvolume_channels_equal_to((a), PA_VOLUME_MUTED)
+
+/** Return 1 if the specified volume has all channels on normal level */
+#define pa_cvolume_is_norm(a) pa_cvolume_channels_equal_to((a), PA_VOLUME_NORM)
+
+/** Multiply two volumes specifications, return the result. This uses PA_VOLUME_NORM as neutral element of multiplication. This is only valid for software volumes! */
+pa_volume_t pa_sw_volume_multiply(pa_volume_t a, pa_volume_t b);
+
+/** Multiply to per-channel volumes and return the result in *dest. This is only valid for software volumes! */
+pa_cvolume *pa_sw_cvolume_multiply(pa_cvolume *dest, const pa_cvolume *a, const pa_cvolume *b);
+
+/** Convert a decibel value to a volume. This is only valid for software volumes! \since 0.4 */
+pa_volume_t pa_sw_volume_from_dB(double f);
+
+/** Convert a volume to a decibel value. This is only valid for software volumes! \since 0.4 */
+double pa_sw_volume_to_dB(pa_volume_t v);
+
+/** Convert a linear factor to a volume. This is only valid for software volumes! \since 0.8 */
+pa_volume_t pa_sw_volume_from_linear(double v);
+
+/** Convert a volume to a linear factor. This is only valid for software volumes! \since 0.8 */
+double pa_sw_volume_to_linear(pa_volume_t v);
+
+#ifdef INFINITY
+#define PA_DECIBEL_MININFTY (-INFINITY)
+#else
+/** This value is used as minus infinity when using pa_volume_{to,from}_dB(). \since 0.4 */
+#define PA_DECIBEL_MININFTY (-200)
+#endif
+
+PA_C_DECL_END
+
+#endif