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Diffstat (limited to 'src/pcm/Volume.hxx')
-rw-r--r-- | src/pcm/Volume.hxx | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/src/pcm/Volume.hxx b/src/pcm/Volume.hxx new file mode 100644 index 000000000..6a6f6196d --- /dev/null +++ b/src/pcm/Volume.hxx @@ -0,0 +1,130 @@ +/* + * Copyright (C) 2003-2013 The Music Player Daemon Project + * http://www.musicpd.org + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program 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 General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ + +#ifndef MPD_PCM_VOLUME_HXX +#define MPD_PCM_VOLUME_HXX + +#include "AudioFormat.hxx" +#include "PcmBuffer.hxx" +#include "PcmDither.hxx" + +#include <stdint.h> +#include <stddef.h> + +#ifndef NDEBUG +#include <assert.h> +#endif + +class Error; +template<typename T> struct ConstBuffer; + +/** + * Number of fractional bits for a fixed-point volume value. + */ +static constexpr unsigned PCM_VOLUME_BITS = 10; + +/** + * This value means "100% volume". + */ +static constexpr unsigned PCM_VOLUME_1 = 1024; +static constexpr int PCM_VOLUME_1S = PCM_VOLUME_1; + +struct AudioFormat; + +/** + * Converts a float value (0.0 = silence, 1.0 = 100% volume) to an + * integer volume value (1000 = 100%). + */ +static inline int +pcm_float_to_volume(float volume) +{ + return volume * PCM_VOLUME_1 + 0.5; +} + +static inline float +pcm_volume_to_float(int volume) +{ + return (float)volume / (float)PCM_VOLUME_1; +} + +/** + * A class that converts samples from one format to another. + */ +class PcmVolume { + SampleFormat format; + + unsigned volume; + + PcmBuffer buffer; + PcmDither dither; + +public: + PcmVolume() + :volume(PCM_VOLUME_1) { +#ifndef NDEBUG + format = SampleFormat::UNDEFINED; +#endif + } + +#ifndef NDEBUG + ~PcmVolume() { + assert(format == SampleFormat::UNDEFINED); + } +#endif + + unsigned GetVolume() const { + return volume; + } + + /** + * @param _volume the volume level in the range + * [0..#PCM_VOLUME_1]; may be bigger than #PCM_VOLUME_1, but + * then it will most likely clip a lot + */ + void SetVolume(unsigned _volume) { + volume = _volume; + } + + /** + * Opens the object, prepare for Apply(). + * + * @param format the sample format + * @param error location to store the error + * @return true on success + */ + bool Open(SampleFormat format, Error &error); + + /** + * Closes the object. After that, you may call Open() again. + */ + void Close() { +#ifndef NDEBUG + assert(format != SampleFormat::UNDEFINED); + format = SampleFormat::UNDEFINED; +#endif + } + + /** + * Apply the volume level. + */ + gcc_pure + ConstBuffer<void> Apply(ConstBuffer<void> src); +}; + +#endif |