src/pulsecore/resampler.h

#ifndef fooresamplerhfoo
#define fooresamplerhfoo

/***
  This file is part of PulseAudio.

  Copyright 2004-2006 Lennart Poettering

  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 2.1 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, see <http://www.gnu.org/licenses/>.
***/

#include <pulse/sample.h>
#include <pulse/channelmap.h>
#include <pulsecore/memblock.h>
#include <pulsecore/memchunk.h>
#include <pulsecore/sconv.h>
#include <pulsecore/remap.h>
#include <pulsecore/filter/lfe-filter.h>

typedef struct pa_resampler pa_resampler;
typedef struct pa_resampler_impl pa_resampler_impl;

struct pa_resampler_impl {
    void (*free)(pa_resampler *r);
    void (*update_rates)(pa_resampler *r);

    /* Returns the number of leftover frames in the input buffer. */
    unsigned (*resample)(pa_resampler *r, const pa_memchunk *in, unsigned in_n_frames, pa_memchunk *out, unsigned *out_n_frames);

    void (*reset)(pa_resampler *r);
    void *data;
};

typedef enum pa_resample_method {
    PA_RESAMPLER_INVALID                 = -1,
    PA_RESAMPLER_SRC_SINC_BEST_QUALITY   = 0, /* = SRC_SINC_BEST_QUALITY */
    PA_RESAMPLER_SRC_SINC_MEDIUM_QUALITY = 1, /* = SRC_SINC_MEDIUM_QUALITY */
    PA_RESAMPLER_SRC_SINC_FASTEST        = 2, /* = SRC_SINC_FASTEST */
    PA_RESAMPLER_SRC_ZERO_ORDER_HOLD     = 3, /* = SRC_ZERO_ORDER_HOLD */
    PA_RESAMPLER_SRC_LINEAR              = 4, /* = SRC_LINEAR */
    PA_RESAMPLER_TRIVIAL,
    PA_RESAMPLER_SPEEX_FLOAT_BASE,
    PA_RESAMPLER_SPEEX_FLOAT_MAX = PA_RESAMPLER_SPEEX_FLOAT_BASE + 10,
    PA_RESAMPLER_SPEEX_FIXED_BASE,
    PA_RESAMPLER_SPEEX_FIXED_MAX = PA_RESAMPLER_SPEEX_FIXED_BASE + 10,
    PA_RESAMPLER_FFMPEG,
    PA_RESAMPLER_AUTO, /* automatic select based on sample format */
    PA_RESAMPLER_COPY,
    PA_RESAMPLER_PEAKS,
    PA_RESAMPLER_SOXR_MQ,
    PA_RESAMPLER_SOXR_HQ,
    PA_RESAMPLER_SOXR_VHQ,
    PA_RESAMPLER_MAX
} pa_resample_method_t;

typedef enum pa_resample_flags {
    PA_RESAMPLER_VARIABLE_RATE = 0x0001U,
    PA_RESAMPLER_NO_REMAP      = 0x0002U,  /* implies NO_REMIX */
    PA_RESAMPLER_NO_REMIX      = 0x0004U,
    PA_RESAMPLER_NO_FILL_SINK  = 0x0010U,
    PA_RESAMPLER_PRODUCE_LFE   = 0x0020U,
    PA_RESAMPLER_CONSUME_LFE   = 0x0040U,
} pa_resample_flags_t;

/* Currently, the soxr reampler has the largest delay of all supported resamplers.
 * The maximum value below has been obtained empirically and contains a safety
 * margin of about 3ms. If the resampler configuration is changed or additional
 * resamplers are added, the constant must be re-evaluated. */
#define PA_RESAMPLER_MAX_DELAY_USEC 33000

struct pa_resampler {
    pa_resample_method_t method;
    pa_resample_flags_t flags;

    pa_sample_spec i_ss, o_ss;
    pa_channel_map i_cm, o_cm;
    size_t i_fz, o_fz, w_fz, w_sz;
    pa_mempool *mempool;

    pa_memchunk to_work_format_buf;
    pa_memchunk remap_buf;
    pa_memchunk resample_buf;
    pa_memchunk from_work_format_buf;
    size_t to_work_format_buf_size;
    size_t remap_buf_size;
    size_t resample_buf_size;
    size_t from_work_format_buf_size;

    /* points to buffer before resampling stage, remap or to_work */
    pa_memchunk *leftover_buf;
    size_t *leftover_buf_size;

    /* have_leftover points to leftover_in_remap or leftover_in_to_work */
    bool *have_leftover;
    bool leftover_in_remap;
    bool leftover_in_to_work;

    pa_sample_format_t work_format;
    uint8_t work_channels;

    pa_convert_func_t to_work_format_func;
    pa_convert_func_t from_work_format_func;

    pa_remap_t remap;
    bool map_required;

    double in_frames;
    double out_frames;
    unsigned gcd;

    pa_lfe_filter_t *lfe_filter;

    pa_resampler_impl impl;
};

pa_resampler* pa_resampler_new(
        pa_mempool *pool,
        const pa_sample_spec *a,
        const pa_channel_map *am,
        const pa_sample_spec *b,
        const pa_channel_map *bm,
	unsigned crossover_freq,
        pa_resample_method_t resample_method,
        pa_resample_flags_t flags);

void pa_resampler_free(pa_resampler *r);

/* Returns the size of an input memory block which is required to return the specified amount of output data */
size_t pa_resampler_request(pa_resampler *r, size_t out_length);

/* Inverse of pa_resampler_request() */
size_t pa_resampler_result(pa_resampler *r, size_t in_length);

/* Returns the maximum size of input blocks we can process without needing bounce buffers larger than the mempool tile size. */
size_t pa_resampler_max_block_size(pa_resampler *r);

/* Pass the specified memory chunk to the resampler and return the newly resampled data */
void pa_resampler_run(pa_resampler *r, const pa_memchunk *in, pa_memchunk *out);

/* Change the input rate of the resampler object */
void pa_resampler_set_input_rate(pa_resampler *r, uint32_t rate);

/* Change the output rate of the resampler object */
void pa_resampler_set_output_rate(pa_resampler *r, uint32_t rate);

/* Reinitialize state of the resampler, possibly due to seeking or other discontinuities */
void pa_resampler_reset(pa_resampler *r);

/* Prepare resampler for use by running some old data through it. */
size_t pa_resampler_prepare(pa_resampler *r, pa_memblockq *history_queue, size_t amount);

/* Rewind resampler */
size_t pa_resampler_rewind(pa_resampler *r, size_t out_bytes, pa_memblockq *history_queue, size_t amount);

/* Return the resampling method of the resampler object */
pa_resample_method_t pa_resampler_get_method(pa_resampler *r);

/* Try to parse the resampler method */
pa_resample_method_t pa_parse_resample_method(const char *string);

/* return a human readable string for the specified resampling method. Inverse of pa_parse_resample_method() */
const char *pa_resample_method_to_string(pa_resample_method_t m);

/* Return 1 when the specified resampling method is supported */
int pa_resample_method_supported(pa_resample_method_t m);

/* Get delay of the resampler in input frames */
double pa_resampler_get_delay(pa_resampler *r, bool allow_negative);

/* Get delay of the resampler in usec */
pa_usec_t pa_resampler_get_delay_usec(pa_resampler *r);

/* Get the GCD of input and outpu rate */
unsigned pa_resampler_get_gcd(pa_resampler *r);

/* Get maximum number of history frames */
size_t pa_resampler_get_max_history(pa_resampler *r);

const pa_channel_map* pa_resampler_input_channel_map(pa_resampler *r);
const pa_sample_spec* pa_resampler_input_sample_spec(pa_resampler *r);
const pa_channel_map* pa_resampler_output_channel_map(pa_resampler *r);
const pa_sample_spec* pa_resampler_output_sample_spec(pa_resampler *r);

/* Implementation specific init functions */
int pa_resampler_ffmpeg_init(pa_resampler *r);
int pa_resampler_libsamplerate_init(pa_resampler *r);
int pa_resampler_peaks_init(pa_resampler *r);
int pa_resampler_speex_init(pa_resampler *r);
int pa_resampler_trivial_init(pa_resampler*r);
int pa_resampler_soxr_init(pa_resampler *r);

/* Resampler-specific quirks */
bool pa_speex_is_fixed_point(void);

#endif