/*****************************************************************************

 * flac.c: flac packetizer module.

 *****************************************************************************

 * Copyright (C) 1999-2017 VLC authors and VideoLAN

 *

 * Authors: Gildas Bazin <gbazin@videolan.org>

 *          Sigmund Augdal Helberg <dnumgis@videolan.org>

 *

 * This program 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.

 *

 * 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 Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser 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.

 *****************************************************************************/

/*****************************************************************************

 * Preamble

 *****************************************************************************/

#ifdef HAVE_CONFIG_H

# include "config.h"

#endif

#include <vlc_common.h>

#include <vlc_plugin.h>

#include <vlc_codec.h>

#include <vlc_block_helper.h>

#include "packetizer_helper.h"

#include "flac.h"

/*****************************************************************************

 * Module descriptor

 *****************************************************************************/

static int  Open (vlc_object_t *);

static void Close(vlc_object_t *);

vlc_module_begin()

    set_subcategory(SUBCAT_SOUT_PACKETIZER)

    set_description(N_("Flac audio packetizer"))

    set_capability("audio packetizer", 50)

    set_callbacks(Open, Close)

vlc_module_end()

/*****************************************************************************

 * decoder_sys_t : FLAC decoder descriptor

 *****************************************************************************/

typedef struct

{

    /*

     * Input properties

     */

    int i_state;

    block_bytestream_t bytestream;

    size_t i_offset;

    /*

     * FLAC properties

     */

    struct flac_stream_info stream_info;

    bool b_stream_info;

    /*

     * Common properties

     */

    date_t pts;

    struct flac_header_info headerinfo;

    size_t i_last_frame_size;

    uint16_t crc;

    size_t i_buf_offset; /* in final buffer before crc check / validation / retry */

    size_t i_buf;

    uint8_t *p_buf;

    int i_next_block_flags;

} decoder_sys_t;

static const int pi_channels_maps[9] =

{

    0,

    AOUT_CHAN_CENTER,

    AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT,

    AOUT_CHAN_CENTER | AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT,

    AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_REARLEFT

     | AOUT_CHAN_REARRIGHT,

    AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER

     | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT,

    AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER

     | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT | AOUT_CHAN_LFE,

    AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER

     | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT | AOUT_CHAN_MIDDLELEFT

     | AOUT_CHAN_MIDDLERIGHT,

    AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER | AOUT_CHAN_REARLEFT

     | AOUT_CHAN_REARRIGHT | AOUT_CHAN_MIDDLELEFT | AOUT_CHAN_MIDDLERIGHT

     | AOUT_CHAN_LFE

};

/*****************************************************************************

 * ProcessHeader: process Flac header.

 *****************************************************************************/

static void ProcessHeader(decoder_t *p_dec)

{

    decoder_sys_t *p_sys = p_dec->p_sys;

    int i_extra = p_dec->fmt_in->i_extra;

    char *p_extra = p_dec->fmt_in->p_extra;

    if (i_extra > 8 && !memcmp(p_extra, "fLaC", 4)) {

        i_extra -= 8;

        p_extra += 8;

    }

    if (i_extra < FLAC_STREAMINFO_SIZE)

        return;

    FLAC_ParseStreamInfo( (uint8_t *) p_extra, &p_sys->stream_info );

    p_sys->b_stream_info = true;

    p_dec->fmt_out.i_extra = i_extra;

    free(p_dec->fmt_out.p_extra);

    p_dec->fmt_out.p_extra = malloc(i_extra);

    if (p_dec->fmt_out.p_extra)

        memcpy(p_dec->fmt_out.p_extra, p_extra, i_extra);

    else

        p_dec->fmt_out.i_extra = 0;

}

/* CRC-8, poly = x^8 + x^2 + x^1 + x^0, init = 0 */

static const uint8_t flac_crc8_table[256] = {

        0x00, 0x07, 0x0E, 0x09, 0x1C, 0x1B, 0x12, 0x15,

        0x38, 0x3F, 0x36, 0x31, 0x24, 0x23, 0x2A, 0x2D,

        0x70, 0x77, 0x7E, 0x79, 0x6C, 0x6B, 0x62, 0x65,

        0x48, 0x4F, 0x46, 0x41, 0x54, 0x53, 0x5A, 0x5D,

        0xE0, 0xE7, 0xEE, 0xE9, 0xFC, 0xFB, 0xF2, 0xF5,

        0xD8, 0xDF, 0xD6, 0xD1, 0xC4, 0xC3, 0xCA, 0xCD,

        0x90, 0x97, 0x9E, 0x99, 0x8C, 0x8B, 0x82, 0x85,

        0xA8, 0xAF, 0xA6, 0xA1, 0xB4, 0xB3, 0xBA, 0xBD,

        0xC7, 0xC0, 0xC9, 0xCE, 0xDB, 0xDC, 0xD5, 0xD2,

        0xFF, 0xF8, 0xF1, 0xF6, 0xE3, 0xE4, 0xED, 0xEA,

        0xB7, 0xB0, 0xB9, 0xBE, 0xAB, 0xAC, 0xA5, 0xA2,

        0x8F, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9D, 0x9A,

        0x27, 0x20, 0x29, 0x2E, 0x3B, 0x3C, 0x35, 0x32,

        0x1F, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0D, 0x0A,

        0x57, 0x50, 0x59, 0x5E, 0x4B, 0x4C, 0x45, 0x42,

        0x6F, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7D, 0x7A,

        0x89, 0x8E, 0x87, 0x80, 0x95, 0x92, 0x9B, 0x9C,

        0xB1, 0xB6, 0xBF, 0xB8, 0xAD, 0xAA, 0xA3, 0xA4,

        0xF9, 0xFE, 0xF7, 0xF0, 0xE5, 0xE2, 0xEB, 0xEC,

        0xC1, 0xC6, 0xCF, 0xC8, 0xDD, 0xDA, 0xD3, 0xD4,

        0x69, 0x6E, 0x67, 0x60, 0x75, 0x72, 0x7B, 0x7C,

        0x51, 0x56, 0x5F, 0x58, 0x4D, 0x4A, 0x43, 0x44,

        0x19, 0x1E, 0x17, 0x10, 0x05, 0x02, 0x0B, 0x0C,

        0x21, 0x26, 0x2F, 0x28, 0x3D, 0x3A, 0x33, 0x34,

        0x4E, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5C, 0x5B,

        0x76, 0x71, 0x78, 0x7F, 0x6A, 0x6D, 0x64, 0x63,

        0x3E, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2C, 0x2B,

        0x06, 0x01, 0x08, 0x0F, 0x1A, 0x1D, 0x14, 0x13,

        0xAE, 0xA9, 0xA0, 0xA7, 0xB2, 0xB5, 0xBC, 0xBB,

        0x96, 0x91, 0x98, 0x9F, 0x8A, 0x8D, 0x84, 0x83,

        0xDE, 0xD9, 0xD0, 0xD7, 0xC2, 0xC5, 0xCC, 0xCB,

        0xE6, 0xE1, 0xE8, 0xEF, 0xFA, 0xFD, 0xF4, 0xF3

};

static uint8_t flac_crc8(const uint8_t *data, size_t len)

{

    uint8_t crc = 0;

    while (len--)

        crc = flac_crc8_table[crc ^ *data++];

    return crc;

}

/* CRC-16, poly = x^16 + x^15 + x^2 + x^0, init = 0 */

static const uint16_t flac_crc16_table[256] = {

    0x0000,  0x8005,  0x800f,  0x000a,  0x801b,  0x001e,  0x0014,  0x8011,

    0x8033,  0x0036,  0x003c,  0x8039,  0x0028,  0x802d,  0x8027,  0x0022,

    0x8063,  0x0066,  0x006c,  0x8069,  0x0078,  0x807d,  0x8077,  0x0072,

    0x0050,  0x8055,  0x805f,  0x005a,  0x804b,  0x004e,  0x0044,  0x8041,

    0x80c3,  0x00c6,  0x00cc,  0x80c9,  0x00d8,  0x80dd,  0x80d7,  0x00d2,

    0x00f0,  0x80f5,  0x80ff,  0x00fa,  0x80eb,  0x00ee,  0x00e4,  0x80e1,

    0x00a0,  0x80a5,  0x80af,  0x00aa,  0x80bb,  0x00be,  0x00b4,  0x80b1,

    0x8093,  0x0096,  0x009c,  0x8099,  0x0088,  0x808d,  0x8087,  0x0082,

    0x8183,  0x0186,  0x018c,  0x8189,  0x0198,  0x819d,  0x8197,  0x0192,

    0x01b0,  0x81b5,  0x81bf,  0x01ba,  0x81ab,  0x01ae,  0x01a4,  0x81a1,

    0x01e0,  0x81e5,  0x81ef,  0x01ea,  0x81fb,  0x01fe,  0x01f4,  0x81f1,

    0x81d3,  0x01d6,  0x01dc,  0x81d9,  0x01c8,  0x81cd,  0x81c7,  0x01c2,

    0x0140,  0x8145,  0x814f,  0x014a,  0x815b,  0x015e,  0x0154,  0x8151,

    0x8173,  0x0176,  0x017c,  0x8179,  0x0168,  0x816d,  0x8167,  0x0162,

    0x8123,  0x0126,  0x012c,  0x8129,  0x0138,  0x813d,  0x8137,  0x0132,

    0x0110,  0x8115,  0x811f,  0x011a,  0x810b,  0x010e,  0x0104,  0x8101,

    0x8303,  0x0306,  0x030c,  0x8309,  0x0318,  0x831d,  0x8317,  0x0312,

    0x0330,  0x8335,  0x833f,  0x033a,  0x832b,  0x032e,  0x0324,  0x8321,

    0x0360,  0x8365,  0x836f,  0x036a,  0x837b,  0x037e,  0x0374,  0x8371,

    0x8353,  0x0356,  0x035c,  0x8359,  0x0348,  0x834d,  0x8347,  0x0342,

    0x03c0,  0x83c5,  0x83cf,  0x03ca,  0x83db,  0x03de,  0x03d4,  0x83d1,

    0x83f3,  0x03f6,  0x03fc,  0x83f9,  0x03e8,  0x83ed,  0x83e7,  0x03e2,

    0x83a3,  0x03a6,  0x03ac,  0x83a9,  0x03b8,  0x83bd,  0x83b7,  0x03b2,

    0x0390,  0x8395,  0x839f,  0x039a,  0x838b,  0x038e,  0x0384,  0x8381,

    0x0280,  0x8285,  0x828f,  0x028a,  0x829b,  0x029e,  0x0294,  0x8291,

    0x82b3,  0x02b6,  0x02bc,  0x82b9,  0x02a8,  0x82ad,  0x82a7,  0x02a2,

    0x82e3,  0x02e6,  0x02ec,  0x82e9,  0x02f8,  0x82fd,  0x82f7,  0x02f2,

    0x02d0,  0x82d5,  0x82df,  0x02da,  0x82cb,  0x02ce,  0x02c4,  0x82c1,

    0x8243,  0x0246,  0x024c,  0x8249,  0x0258,  0x825d,  0x8257,  0x0252,

    0x0270,  0x8275,  0x827f,  0x027a,  0x826b,  0x026e,  0x0264,  0x8261,

    0x0220,  0x8225,  0x822f,  0x022a,  0x823b,  0x023e,  0x0234,  0x8231,

    0x8213,  0x0216,  0x021c,  0x8219,  0x0208,  0x820d,  0x8207,  0x0202

};

static uint16_t flac_crc16(uint16_t crc, uint8_t byte)

{

    return (crc << 8) ^ flac_crc16_table[(crc >> 8) ^ byte];

}

#if 0

/* Gives the previous CRC value, before hashing last_byte through it */

static uint16_t flac_crc16_undo(uint16_t crc, const uint8_t last_byte)

{

    /*

     * Given a byte b, gives a position X in flac_crc16_table, such as:

     *      flac_crc16_rev_table[flac_crc16_table[X] & 0xff] == X

     * This works because flac_crc16_table[i] & 0xff yields 256 unique values.

     */

    static const uint8_t flac_crc16_rev_table[256] = {

        0x00, 0x7f, 0xff, 0x80, 0x7e, 0x01, 0x81, 0xfe,

        0xfc, 0x83, 0x03, 0x7c, 0x82, 0xfd, 0x7d, 0x02,

        0x78, 0x07, 0x87, 0xf8, 0x06, 0x79, 0xf9, 0x86,

        0x84, 0xfb, 0x7b, 0x04, 0xfa, 0x85, 0x05, 0x7a,

        0xf0, 0x8f, 0x0f, 0x70, 0x8e, 0xf1, 0x71, 0x0e,

        0x0c, 0x73, 0xf3, 0x8c, 0x72, 0x0d, 0x8d, 0xf2,

        0x88, 0xf7, 0x77, 0x08, 0xf6, 0x89, 0x09, 0x76,

        0x74, 0x0b, 0x8b, 0xf4, 0x0a, 0x75, 0xf5, 0x8a,

        0x60, 0x1f, 0x9f, 0xe0, 0x1e, 0x61, 0xe1, 0x9e,

        0x9c, 0xe3, 0x63, 0x1c, 0xe2, 0x9d, 0x1d, 0x62,

        0x18, 0x67, 0xe7, 0x98, 0x66, 0x19, 0x99, 0xe6,

        0xe4, 0x9b, 0x1b, 0x64, 0x9a, 0xe5, 0x65, 0x1a,

        0x90, 0xef, 0x6f, 0x10, 0xee, 0x91, 0x11, 0x6e,

        0x6c, 0x13, 0x93, 0xec, 0x12, 0x6d, 0xed, 0x92,

        0xe8, 0x97, 0x17, 0x68, 0x96, 0xe9, 0x69, 0x16,

        0x14, 0x6b, 0xeb, 0x94, 0x6a, 0x15, 0x95, 0xea,

        0xc0, 0xbf, 0x3f, 0x40, 0xbe, 0xc1, 0x41, 0x3e,

        0x3c, 0x43, 0xc3, 0xbc, 0x42, 0x3d, 0xbd, 0xc2,

        0xb8, 0xc7, 0x47, 0x38, 0xc6, 0xb9, 0x39, 0x46,

        0x44, 0x3b, 0xbb, 0xc4, 0x3a, 0x45, 0xc5, 0xba,

        0x30, 0x4f, 0xcf, 0xb0, 0x4e, 0x31, 0xb1, 0xce,

        0xcc, 0xb3, 0x33, 0x4c, 0xb2, 0xcd, 0x4d, 0x32,

        0x48, 0x37, 0xb7, 0xc8, 0x36, 0x49, 0xc9, 0xb6,

        0xb4, 0xcb, 0x4b, 0x34, 0xca, 0xb5, 0x35, 0x4a,

        0xa0, 0xdf, 0x5f, 0x20, 0xde, 0xa1, 0x21, 0x5e,

        0x5c, 0x23, 0xa3, 0xdc, 0x22, 0x5d, 0xdd, 0xa2,

        0xd8, 0xa7, 0x27, 0x58, 0xa6, 0xd9, 0x59, 0x26,

        0x24, 0x5b, 0xdb, 0xa4, 0x5a, 0x25, 0xa5, 0xda,

        0x50, 0x2f, 0xaf, 0xd0, 0x2e, 0x51, 0xd1, 0xae,

        0xac, 0xd3, 0x53, 0x2c, 0xd2, 0xad, 0x2d, 0x52,

        0x28, 0x57, 0xd7, 0xa8, 0x56, 0x29, 0xa9, 0xd6,

        0xd4, 0xab, 0x2b, 0x54, 0xaa, 0xd5, 0x55, 0x2a,

    };

    uint8_t idx = flac_crc16_rev_table[crc & 0xff];

    return ((idx ^ last_byte) << 8) | ((crc ^ flac_crc16_table[idx]) >> 8);

}

#endif

static void Flush(decoder_t *p_dec)

{

    decoder_sys_t *p_sys = p_dec->p_sys;

    p_sys->i_state = STATE_NOSYNC;

    p_sys->i_offset = 0;

    date_Set( &p_sys->pts, VLC_TICK_INVALID );

    block_BytestreamEmpty(&p_sys->bytestream);

}

static const uint8_t * FLACStartcodeHelper(const uint8_t *p, const uint8_t *end)

{

    while( p && p < end )

    {

        if( (p = memchr(p, 0xFF, end - p)) )

        {

            if( end - p > 1 && (p[1] & 0xFE) == 0xF8 )

                return p;

            else

                p++;

        }

    }

    return NULL;

}

static bool FLACStartcodeMatcher(uint8_t i, size_t i_pos, const uint8_t *p_startcode)

{

    VLC_UNUSED(p_startcode);

    return (i_pos == 0) ? i == 0xFF : (i & 0xFE) == 0xF8;

}

/* */

static block_t *Packetize(decoder_t *p_dec, block_t **pp_block)

{

    decoder_sys_t *p_sys = p_dec->p_sys;

    uint8_t p_header[FLAC_HEADER_SIZE_MAX];

    block_t *out = NULL, *in = NULL;

    if ( pp_block && *pp_block)

    {

        in = *pp_block;

        *pp_block = NULL;

        if (in->i_flags&(BLOCK_FLAG_DISCONTINUITY|BLOCK_FLAG_CORRUPTED)) {

            Flush(p_dec);

            p_sys->i_next_block_flags |= BLOCK_FLAG_DISCONTINUITY;

            if (in->i_flags&BLOCK_FLAG_CORRUPTED) {

                block_Release(in);

                return NULL;

            }

        }

    }

    if (!p_sys->b_stream_info)

        ProcessHeader(p_dec);

    if (p_sys->stream_info.channels > 8)

    {

        if(in)

            block_Release(in);

        msg_Err(p_dec, "This stream uses too many audio channels (%d > 8)",

            p_sys->stream_info.channels);

        return NULL;

    }

    if ( in )

        block_BytestreamPush(&p_sys->bytestream, in);

    while (1) switch (p_sys->i_state) {

    case STATE_NOSYNC:

        if(block_FindStartcodeFromOffset(&p_sys->bytestream, &p_sys->i_offset,

                                         NULL, 2,

                                         FLACStartcodeHelper,

                                         FLACStartcodeMatcher) == VLC_SUCCESS)

        {

            p_sys->i_state = STATE_SYNC;

        }

        /* First Sync is now on bytestream head, offset == 0 */

        block_SkipBytes(&p_sys->bytestream, p_sys->i_offset);

        block_BytestreamFlush(&p_sys->bytestream);

        p_sys->i_offset = 0;

        if( p_sys->i_state != STATE_SYNC )

            return NULL; /* Need more data */

        /* fallthrough */

    case STATE_SYNC:

        /* Sync state is unverified until we have read frame header and checked CRC

           Once validated, we'll send data from NEXT_SYNC state where we'll

           compute frame size */

        p_sys->i_state = STATE_HEADER;

        /* fallthrough */

    case STATE_HEADER:

    {

        /* Get FLAC frame header (MAX_FLAC_HEADER_SIZE bytes) */

        if (block_PeekBytes(&p_sys->bytestream, p_header, FLAC_HEADER_SIZE_MAX))

            return NULL; /* Need more data */

        /* Check if frame is valid and get frame info */

        const struct flac_stream_info *streaminfo =

                p_sys->b_stream_info ? &p_sys->stream_info : NULL;

        struct flac_header_info headerinfo;

        int i_ret = FLAC_ParseSyncInfo(p_header, FLAC_HEADER_SIZE_MAX, streaminfo,

                                       flac_crc8, &headerinfo);

        if (!i_ret || !FLAC_CheckFrameInfo(streaminfo, &headerinfo)) {

            msg_Dbg(p_dec, "emulated sync word");

            block_SkipByte(&p_sys->bytestream);

            p_sys->i_offset = 0;

            p_sys->i_state = STATE_NOSYNC;

            break;

        }

        p_sys->headerinfo = headerinfo;

        p_sys->i_state = STATE_NEXT_SYNC;

        p_sys->i_offset = FLAC_FRAME_SIZE_MIN;

        p_sys->i_buf_offset = 0;

        p_sys->crc = 0;

        /* We have to read until next frame sync code to compute current frame size

         * from that boundary.

         * The confusing part below is that sync code needs to be verified in case

         * it would appear in data, so we also need to check next frame header CRC

         */

    }

        /* fallthrough */

    case STATE_NEXT_SYNC:

    {

        /* First Sync is on bytestream head, offset will be the position

         * of the next sync code candidate */

        if(block_FindStartcodeFromOffset(&p_sys->bytestream, &p_sys->i_offset,

                                         NULL, 2,

                                         FLACStartcodeHelper,

                                         FLACStartcodeMatcher) != VLC_SUCCESS)

        {

            size_t i_remain = block_BytestreamRemaining( &p_sys->bytestream );

            if( pp_block == NULL && i_remain > FLAC_FRAME_SIZE_MIN ) /* EOF/Drain */

            {

                /* There is no other synccode in the bytestream,

                 * we assume the end of our flac frame is end of bytestream */

                p_sys->i_offset = i_remain;

                p_sys->i_state = STATE_GET_DATA;

                continue;

            }

            return NULL;

        }

        /* Check next header */

        uint8_t nextheader[FLAC_HEADER_SIZE_MAX];

        if (block_PeekOffsetBytes(&p_sys->bytestream, p_sys->i_offset,

                                  nextheader, FLAC_HEADER_SIZE_MAX))

            return NULL; /* Need more data */

        const struct flac_stream_info *streaminfo =

                p_sys->b_stream_info ? &p_sys->stream_info : NULL;

        struct flac_header_info dummy;

        /* Check if frame is valid and get frame info */

        if(!FLAC_ParseSyncInfo(nextheader, FLAC_HEADER_SIZE_MAX, streaminfo, NULL, &dummy)||

           !FLAC_CheckFrameInfo(streaminfo, &dummy))

        {

            /* Keep trying to find next sync point in bytestream */

            p_sys->i_offset++;

            continue;

        }

        p_sys->i_state = STATE_GET_DATA;

        continue;

    }

    case STATE_GET_DATA:

        /* i_offset is the next sync point candidate

         * our frame_size is the offset from the first sync */

        if( pp_block != NULL &&

            p_sys->b_stream_info &&

            p_sys->stream_info.min_framesize > p_sys->i_offset )

        {

            p_sys->i_offset += 1;

            p_sys->i_state = STATE_NEXT_SYNC;

            break;

        }

        else if( p_sys->b_stream_info &&

                 p_sys->stream_info.max_framesize > FLAC_FRAME_SIZE_MIN &&

                 p_sys->stream_info.max_framesize < p_sys->i_offset )

        {

            /* Something went wrong, truncate stream head and restart */

            msg_Warn(p_dec, "discarding bytes as we're over framesize %u, %zu",

                     p_sys->stream_info.max_framesize,

                     p_sys->i_offset);

            if( block_SkipBytes( &p_sys->bytestream,

                                 FLAC_HEADER_SIZE_MAX + 2 ) != VLC_SUCCESS )

                return NULL;

            block_BytestreamFlush( &p_sys->bytestream );

            p_sys->crc = 0;

            p_sys->i_buf_offset = 0;

            p_sys->i_offset = 0;

            p_sys->i_state = STATE_NOSYNC;

            p_sys->i_next_block_flags |= BLOCK_FLAG_DISCONTINUITY;

            break;

        }

        else

        {

            /* Allocate enough for storage */

            if( p_sys->i_offset > p_sys->i_buf )

            {

                size_t i_min_alloc = __MAX(p_sys->i_last_frame_size, p_sys->i_offset);

                uint8_t *p_realloc = realloc( p_sys->p_buf, i_min_alloc );

                if( p_realloc )

                {

                    p_sys->i_buf = i_min_alloc;

                    p_sys->p_buf = p_realloc;

                }

                if ( !p_sys->p_buf )

                    return NULL;

            }

            /* Copy from previous sync point up to to current (offset) */

            if( block_PeekOffsetBytes( &p_sys->bytestream, p_sys->i_buf_offset,

                                       &p_sys->p_buf[p_sys->i_buf_offset],

                                       p_sys->i_offset - p_sys->i_buf_offset ))

                return NULL;

            /* update crc to include this data chunk */

            for( size_t i = p_sys->i_buf_offset; i < p_sys->i_offset - 2; i++ )

                p_sys->crc = flac_crc16( p_sys->crc, p_sys->p_buf[i] );

            uint16_t stream_crc = GetWBE(&p_sys->p_buf[p_sys->i_offset - 2]);

            if( stream_crc != p_sys->crc )

            {

                /* False positive syncpoint as the CRC does not match */

                /* Add the 2 last bytes which were not the CRC sum, and go for next sync point */

                p_sys->crc = flac_crc16( p_sys->crc, p_sys->p_buf[p_sys->i_offset - 2] );

                p_sys->crc = flac_crc16( p_sys->crc, p_sys->p_buf[p_sys->i_offset - 1] );

                p_sys->i_buf_offset = p_sys->i_offset;

                p_sys->i_offset += 1;

                p_sys->i_state = !pp_block ? STATE_NOSYNC : STATE_NEXT_SYNC;

                break; /* continue */

            }

            p_sys->i_state = STATE_SEND_DATA;

            /* frame size between the two sync codes is now known */

            p_sys->i_last_frame_size = p_sys->i_offset;

            p_sys->i_buf = p_sys->i_offset;

            /* clean */

            block_SkipBytes( &p_sys->bytestream, p_sys->i_offset );

            block_BytestreamFlush( &p_sys->bytestream );

            p_sys->i_offset = 0;

            p_sys->crc = 0;

            p_sys->i_buf_offset = 0;

            if( block_BytestreamRemaining(&p_sys->bytestream) > 0 || pp_block == NULL /* drain */)

                p_sys->i_state = STATE_SEND_DATA;

            else

                p_sys->i_state = STATE_NOSYNC;

        }

        break;

    case STATE_SEND_DATA:

        p_dec->fmt_out.audio.i_rate = p_sys->headerinfo.i_rate;

        p_dec->fmt_out.audio.i_channels = p_sys->headerinfo.i_channels;

        p_dec->fmt_out.audio.i_physical_channels = pi_channels_maps[p_sys->stream_info.channels];

        if( p_sys->bytestream.p_block &&

            p_sys->bytestream.p_block->i_pts > date_Get( &p_sys->pts ) &&

            p_sys->bytestream.p_block->i_pts != VLC_TICK_INVALID )

        {

            date_Init( &p_sys->pts, p_sys->headerinfo.i_rate, 1 );

            date_Set( &p_sys->pts, p_sys->bytestream.p_block->i_pts );

            p_sys->bytestream.p_block->i_pts = VLC_TICK_INVALID;

        }

        out = block_heap_Alloc( p_sys->p_buf, p_sys->i_buf );

        if( out )

        {

            out->i_dts = out->i_pts = date_Get( &p_sys->pts );

            out->i_flags = p_sys->i_next_block_flags;

            p_sys->i_next_block_flags = 0;

        }

        else

            p_sys->p_buf = NULL;

        date_Increment( &p_sys->pts, p_sys->headerinfo.i_frame_length );

        if( out )

            out->i_length = date_Get( &p_sys->pts ) - out->i_pts;

        else

            free( p_sys->p_buf );

        p_sys->i_buf_offset = 0;

        p_sys->i_buf = 0;

        p_sys->p_buf = NULL;

        p_sys->i_offset = 0;

        p_sys->i_state = STATE_NOSYNC;

        /* So p_block doesn't get re-added several times */

        if ( pp_block )

            *pp_block = block_BytestreamPop(&p_sys->bytestream);

        return out;

    }

    return NULL;

}

static int Open(vlc_object_t *p_this)

{

    decoder_t *p_dec = (decoder_t*)p_this;

    decoder_sys_t *p_sys;

    if (p_dec->fmt_in->i_codec != VLC_CODEC_FLAC)

        return VLC_EGENERIC;

    /* */

    p_dec->p_sys = p_sys = malloc(sizeof(*p_sys));

    if (!p_sys)

        return VLC_ENOMEM;

    p_sys->i_state       = STATE_NOSYNC;

    p_sys->i_offset      = 0;

    p_sys->b_stream_info = false;

    p_sys->i_last_frame_size = FLAC_FRAME_SIZE_MIN;

    p_sys->headerinfo.i_pts  = VLC_TICK_INVALID;

    p_sys->i_buf_offset  = 0;

    p_sys->i_buf         = 0;

    p_sys->p_buf         = NULL;

    p_sys->i_next_block_flags = 0;

    block_BytestreamInit(&p_sys->bytestream);

    date_Init( &p_sys->pts, 1, 1 );

    /* */

    es_format_Copy(&p_dec->fmt_out, p_dec->fmt_in);

    p_dec->fmt_out.i_codec = VLC_CODEC_FLAC;

    p_dec->fmt_out.b_packetized = true;

    /* */

    p_dec->pf_packetize = Packetize;

    p_dec->pf_flush     = Flush;

    p_dec->pf_get_cc    = NULL;

    return VLC_SUCCESS;

}

static void Close(vlc_object_t *p_this)

{

    decoder_t *p_dec = (decoder_t *)p_this;

    decoder_sys_t *p_sys = p_dec->p_sys;

    block_BytestreamRelease(&p_sys->bytestream);

    free(p_sys->p_buf);

    free(p_sys);

}