src/libs/decoders/flac.c

/*
 *  SPDX-License-Identifier: GPL-2.0-or-later
 *
 *  Copyright (C) 2001-2017  Ryan C. Gordon <icculus@icculus.org>
 *  Copyright (C) 2018-2019  Kevin R. Croft <krcroft@gmail.com>
 *  Copyright (C) 2020-2020  The DOSBox-X project
 *
 *  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.
 */

/*
 *  DOSBox-X FLAC decoder API implementation
 *  ----------------------------------------
 *  This decoder makes use of the dr_flac library by David Reid (mackron@gmail.com)
 *    - dr_libs: https://github.com/mackron/dr_libs (source)
 *    - dr_flac: http://mackron.github.io/dr_flac.html (website)
 */

#include <math.h> /* for llroundf */

#include "SDL_sound.h"
#define __SDL_SOUND_INTERNAL__
#include "SDL_sound_internal.h"

#define DR_FLAC_IMPLEMENTATION
#define DR_FLAC_NO_STDIO 1
#define DR_FLAC_NO_WIN32_IO 1
#define DR_FLAC_NO_OGG 1
#define DR_FLAC_BUFFER_SIZE 8192
#include "dr_flac.h"

static size_t flac_read(void* pUserData, void* pBufferOut, size_t bytesToRead)
{
    Uint8 *ptr = (Uint8 *) pBufferOut;
    Sound_Sample *sample = (Sound_Sample *) pUserData;
    Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
    SDL_RWops *rwops = internal->rw;
    size_t bytes_read = 0;

    while (bytes_read < bytesToRead)
    {
        const size_t rc = SDL_RWread(rwops, ptr, 1, bytesToRead - bytes_read);
        if (rc == 0) {
            sample->flags |= SOUND_SAMPLEFLAG_EOF;
            break;
        } /* if */
        bytes_read += rc;
        ptr += rc;
    } /* while */

    return bytes_read;
} /* flac_read */

static drflac_bool32 flac_seek(void* pUserData, int offset, drflac_seek_origin origin)
{
    const int whence = (origin == drflac_seek_origin_start) ? RW_SEEK_SET : RW_SEEK_CUR;
    Sound_Sample *sample = (Sound_Sample *) pUserData;
    Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
    return (SDL_RWseek(internal->rw, offset, whence) != -1) ? DRFLAC_TRUE : DRFLAC_FALSE;
} /* flac_seek */


static int FLAC_init(void)
{
    return 1;  /* always succeeds. */
} /* FLAC_init */


static void FLAC_quit(void)
{
    /* it's a no-op. */
} /* FLAC_quit */

static int FLAC_open(Sound_Sample *sample, const char *ext)
{
    (void) ext; // deliberately unused, but present for API compliance
    Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
    drflac *dr = drflac_open(flac_read, flac_seek, sample, NULL);

    if (!dr) {
        BAIL_IF_MACRO(sample->flags & SOUND_SAMPLEFLAG_ERROR, ERR_IO_ERROR, 0);
        BAIL_MACRO("FLAC: Not a FLAC stream.", 0);
    } /* if */

    SNDDBG(("FLAC: Accepting data stream.\n"));
    sample->flags = SOUND_SAMPLEFLAG_CANSEEK;

    sample->actual.channels = dr->channels;
    sample->actual.rate = dr->sampleRate;
    sample->actual.format = AUDIO_S16SYS; /* returns native byte-order based on architecture */

    const Uint64 frames = (Uint64) dr->totalPCMFrameCount;
    if (frames == 0) {
        internal->total_time = -1;
    }
    else {
        const Uint32 rate = (Uint32) dr->sampleRate;
        internal->total_time = ( (Sint32)frames / rate) * 1000;
        internal->total_time += ((frames % rate) * 1000) / rate;
    } /* else */

    internal->decoder_private = dr;

    return 1;
} /* FLAC_open */



static void FLAC_close(Sound_Sample *sample)
{
    Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
    drflac *dr = (drflac *) internal->decoder_private;
    drflac_close(dr);
} /* FLAC_close */


static Uint32 FLAC_read(Sound_Sample *sample, void* buffer, Uint32 desired_frames)
{
    Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
    drflac *dr = (drflac *) internal->decoder_private;
    const drflac_uint64 decoded_frames = drflac_read_pcm_frames_s16(dr,
                                                                    desired_frames,
                                                                    (drflac_int16 *) buffer);
    return (Uint32) decoded_frames;
} /* FLAC_read */


static int FLAC_rewind(Sound_Sample *sample)
{
    Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
    drflac *dr = (drflac *) internal->decoder_private;
    return (drflac_seek_to_pcm_frame(dr, 0) == DRFLAC_TRUE);
} /* FLAC_rewind */

static int FLAC_seek(Sound_Sample *sample, Uint32 ms)
{
    Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
    drflac *dr = (drflac *) internal->decoder_private;
    const float frames_per_ms = ((float) sample->actual.rate) / 1000.0f;
    const drflac_uint64 frame_offset = llroundf(frames_per_ms * ms);
    return (drflac_seek_to_pcm_frame(dr, frame_offset) == DRFLAC_TRUE);
} /* FLAC_seek */


static const char *extensions_flac[] = { "FLAC", "FLA", NULL };
const Sound_DecoderFunctions __Sound_DecoderFunctions_FLAC =
{
    {
        extensions_flac,
        "Free Lossless Audio Codec (FLAC)",
        "The DOSBox-X project"
    },

    FLAC_init,       /*   init() method */
    FLAC_quit,       /*   quit() method */
    FLAC_open,       /*   open() method */
    FLAC_close,      /*  close() method */
    FLAC_read,       /*   read() method */
    FLAC_rewind,     /* rewind() method */
    FLAC_seek        /*   seek() method */
};

/* end of flac.c ... */