Add helpers for converting to/from normalized (perceptual) volume
These routines were taken from alsamixer and converted to fixed point for Rockbox. Change-Id: I64e8bf08da02b1e6e3ef10fdc78254bf8e87ff20
This commit is contained in:
Aidan MacDonald
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66519000f4
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3 changed files with 132 additions and 0 deletions
102
apps/misc.c
102
apps/misc.c
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@ -1664,3 +1664,105 @@ int core_load_bmp(const char * filename, struct bitmap *bm, const int bmformat,
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return handle;
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}
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#endif /* ndef __PCTOOL__ */
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/*
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* Normalized volume routines adapted from alsamixer volume_mapping.c
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*/
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/*
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* Copyright (c) 2010 Clemens Ladisch <clemens@ladisch.de>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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/*
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* "The mapping is designed so that the position in the interval is proportional
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* to the volume as a human ear would perceive it (i.e., the position is the
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* cubic root of the linear sample multiplication factor). For controls with
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* a small range (24 dB or less), the mapping is linear in the dB values so
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* that each step has the same size visually. Only for controls without dB
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* information, a linear mapping of the hardware volume register values is used
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* (this is the same algorithm as used in the old alsamixer)."
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*/
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#define NVOL_FRACBITS 16
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#define NVOL_UNITY (1L << NVOL_FRACBITS)
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#define NVOL_FACTOR (600L << NVOL_FRACBITS)
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#define NVOL_MAX_LINEAR_DB_SCALE (240L << NVOL_FRACBITS)
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#define nvol_div(x,y) fp_div((x), (y), NVOL_FRACBITS)
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#define nvol_mul(x,y) fp_mul((x), (y), NVOL_FRACBITS)
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#define nvol_exp10(x) fp_exp10((x), NVOL_FRACBITS)
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#define nvol_log10(x) fp_log10((x), NVOL_FRACBITS)
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static bool use_linear_dB_scale(long min_vol, long max_vol)
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{
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/*
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* Alsamixer uses a linear scale for small ranges.
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* Commented out so perceptual volume works as advertised on all targets.
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*/
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/*
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return max_vol - min_vol <= NVOL_MAX_LINEAR_DB_SCALE;
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*/
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(void)min_vol;
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(void)max_vol;
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return false;
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}
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long to_normalized_volume(long vol, long min_vol, long max_vol, long max_norm)
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{
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long norm, min_norm;
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vol <<= NVOL_FRACBITS;
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min_vol <<= NVOL_FRACBITS;
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max_vol <<= NVOL_FRACBITS;
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max_norm <<= NVOL_FRACBITS;
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if (use_linear_dB_scale(min_vol, max_vol))
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{
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norm = nvol_div(vol - min_vol, max_vol - min_vol);
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}
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else
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{
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min_norm = nvol_exp10(nvol_div(min_vol - max_vol, NVOL_FACTOR));
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norm = nvol_exp10(nvol_div(vol - max_vol, NVOL_FACTOR));
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norm = nvol_div(norm - min_norm, NVOL_UNITY - min_norm);
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}
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return nvol_mul(norm, max_norm) >> NVOL_FRACBITS;
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}
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long from_normalized_volume(long norm, long min_vol, long max_vol, long max_norm)
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{
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long vol, min_norm;
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norm <<= NVOL_FRACBITS;
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min_vol <<= NVOL_FRACBITS;
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max_vol <<= NVOL_FRACBITS;
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max_norm <<= NVOL_FRACBITS;
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vol = nvol_div(norm, max_norm);
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if (use_linear_dB_scale(min_vol, max_vol))
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{
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vol = nvol_mul(vol, max_vol - min_vol) + min_vol;
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}
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else
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{
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min_norm = nvol_exp10(nvol_div(min_vol - max_vol, NVOL_FACTOR));
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vol = nvol_mul(vol, NVOL_UNITY - min_norm) + min_norm;
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vol = nvol_mul(nvol_log10(vol), NVOL_FACTOR) + max_vol;
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}
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return vol >> NVOL_FRACBITS;
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}
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@ -238,4 +238,12 @@ int core_load_bmp(const char *filename, struct bitmap *bm, const int bmformat,
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ssize_t *buf_reqd, struct buflib_callbacks *ops);
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#endif
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/* Convert a volume (in tenth dB) in the range [min_vol, max_vol]
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* to a normalized linear value in the range [0, max_norm]. */
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long to_normalized_volume(long vol, long min_vol, long max_vol, long max_norm);
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/* Inverse of to_normalized_volume(), returns the volume in tenth dB
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* for the given normalized volume. */
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long from_normalized_volume(long norm, long min_vol, long max_vol, long max_norm);
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#endif /* MISC_H */
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@ -143,3 +143,25 @@ From: https://github.com/cnSchwarzer/bsdiff-win
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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*************************************************************************
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In: apps/misc.c, to_normalized_volume and from_normalized_volume
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From: https://git.alsa-project.org/?p=alsa-utils.git
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alsamixer/volume_mapping.c
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*************************************************************************
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/*
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* Copyright (c) 2010 Clemens Ladisch <clemens@ladisch.de>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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