/*****************************************************************************
 * src.c : Secret Rabbit Code (a.k.a. libsamplerate) resampler
 *****************************************************************************
 * Copyright (C) 2011 Rémi Denis-Courmont
 *
 * 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.
 *****************************************************************************/

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <vlc_common.h>
#include <vlc_plugin.h>
#include <vlc_aout.h>
#include <vlc_filter.h>
#include <samplerate.h>
#include <math.h>

#define SRC_CONV_TYPE_TEXT N_("Sample rate converter type")
#define SRC_CONV_TYPE_LONGTEXT N_( \
    "Different resampling algorithms are supported. " \
    "The best one is slower, while the fast one exhibits low quality.")
static const int conv_type_values[] = {
    SRC_SINC_BEST_QUALITY, SRC_SINC_MEDIUM_QUALITY, SRC_SINC_FASTEST,
    SRC_ZERO_ORDER_HOLD, SRC_LINEAR,
};
static const char *const conv_type_texts[] = {
    "Sinc function (best quality)", "Sinc function (medium quality)",
    "Sinc function (fast)", "Zero Order Hold (fastest)", "Linear (fastest)",
};

static int Open (vlc_object_t *);
static void Close (vlc_object_t *);

vlc_module_begin ()
    set_shortname (N_("SRC resampler"))
    set_description (N_("Secret Rabbit Code (libsamplerate) resampler") )
    set_category (CAT_AUDIO)
    set_subcategory (SUBCAT_AUDIO_MISC)
    add_integer ("src-converter-type", SRC_SINC_MEDIUM_QUALITY,
                 SRC_CONV_TYPE_TEXT, SRC_CONV_TYPE_LONGTEXT, true)
        change_integer_list (conv_type_values, conv_type_texts)
    set_capability ("audio filter", 50)
    set_callbacks (Open, Close)
vlc_module_end ()

static block_t *Resample (filter_t *, block_t *);

static int Open (vlc_object_t *obj)
{
    filter_t *filter = (filter_t *)obj;

    /* Only float->float */
    if (filter->fmt_in.audio.i_format != VLC_CODEC_FL32
     || filter->fmt_out.audio.i_format != VLC_CODEC_FL32
    /* No channels remapping */
     || filter->fmt_in.audio.i_physical_channels
                                  != filter->fmt_out.audio.i_physical_channels
     || filter->fmt_in.audio.i_original_channels
                                  != filter->fmt_out.audio.i_original_channels
    /* Different sample rate */
     || filter->fmt_in.audio.i_rate == filter->fmt_out.audio.i_rate)
        return VLC_EGENERIC;

    int type = var_InheritInteger (obj, "src-converter-type");
    int channels = aout_FormatNbChannels (&filter->fmt_in.audio);
    int err;

    SRC_STATE *s = src_new (type, channels, &err);
    if (s == NULL)
    {
        msg_Err (obj, "cannot initialize resampler: %s", src_strerror (err));
        return VLC_EGENERIC;
    }

    filter->p_sys = (filter_sys_t *)s;
    filter->pf_audio_filter = Resample;
    return VLC_SUCCESS;
}

static void Close (vlc_object_t *obj)
{
    filter_t *filter = (filter_t *)obj;
    SRC_STATE *s = (SRC_STATE *)filter->p_sys;

    src_delete (s);
}

static block_t *Resample (filter_t *filter, block_t *in)
{
    block_t *out = NULL;
    const size_t framesize = filter->fmt_out.audio.i_bytes_per_frame;

    SRC_STATE *s = (SRC_STATE *)filter->p_sys;
    SRC_DATA src;

    src.src_ratio = (double)filter->fmt_out.audio.i_rate
                  / (double)filter->fmt_in.audio.i_rate;

    int err = src_set_ratio (s, src.src_ratio);
    if (err != 0)
    {
        msg_Err (filter, "cannot update resampling ratio: %s",
                 src_strerror (err));
        goto error;
    }

    src.input_frames = in->i_nb_samples;
    src.output_frames = ceil (src.src_ratio * src.input_frames);
    src.end_of_input = 0;

    out = block_Alloc (src.output_frames * framesize);
    if (unlikely(out == NULL))
        goto error;

    src.data_in = (float *)in->p_buffer;
    src.data_out = (float *)out->p_buffer;

    err = src_process (s, &src);
    if (err != 0)
    {
        msg_Err (filter, "cannot resample: %s", src_strerror (err));
        block_Release (out);
        out = NULL;
        goto error;
    }

    if (src.input_frames_used < src.input_frames)
        msg_Err (filter, "lost %ld of %ld input frames",
                 src.input_frames - src.input_frames_used, src.input_frames);

    out->i_buffer = src.output_frames_gen * framesize;
    out->i_nb_samples = src.output_frames_gen;
    out->i_pts = in->i_pts;
    out->i_length = src.output_frames_gen * CLOCK_FREQ
                  / filter->fmt_out.audio.i_rate;
error:
    block_Release (in);
    return out;
}
