/*
  * WavPack lossless audio decoder

  * Copyright (c) 2006,2011 Konstantin Shishkov

  *

  * This file is part of FFmpeg.
  *
  * FFmpeg 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.

  *

  * FFmpeg 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 FFmpeg; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */

 #define BITSTREAM_READER_LE

 
 #include "libavutil/audioconvert.h"

 #include "avcodec.h"

 #include "get_bits.h"

 #include "unary.h"

 
 /**

  * @file

  * WavPack lossless audio decoder
  */
 

 #define WV_MONO           0x00000004
 #define WV_JOINT_STEREO   0x00000010
 #define WV_FALSE_STEREO   0x40000000

 #define WV_HYBRID_MODE    0x00000008
 #define WV_HYBRID_SHAPE   0x00000008
 #define WV_HYBRID_BITRATE 0x00000200
 #define WV_HYBRID_BALANCE 0x00000400
 

 #define WV_FLT_SHIFT_ONES 0x01
 #define WV_FLT_SHIFT_SAME 0x02
 #define WV_FLT_SHIFT_SENT 0x04
 #define WV_FLT_ZERO_SENT  0x08
 #define WV_FLT_ZERO_SIGN  0x10
 

 enum WP_ID_Flags {

     WP_IDF_MASK   = 0x1F,
     WP_IDF_IGNORE = 0x20,
     WP_IDF_ODD    = 0x40,
     WP_IDF_LONG   = 0x80
 };
 

 enum WP_ID {

     WP_ID_DUMMY = 0,
     WP_ID_ENCINFO,
     WP_ID_DECTERMS,
     WP_ID_DECWEIGHTS,
     WP_ID_DECSAMPLES,
     WP_ID_ENTROPY,
     WP_ID_HYBRID,
     WP_ID_SHAPING,
     WP_ID_FLOATINFO,
     WP_ID_INT32INFO,
     WP_ID_DATA,
     WP_ID_CORR,

     WP_ID_EXTRABITS,

     WP_ID_CHANINFO
 };
 

 typedef struct SavedContext {
     int offset;
     int size;
     int bits_used;
     uint32_t crc;
 } SavedContext;
 

 #define MAX_TERMS 16
 
 typedef struct Decorr {
     int delta;
     int value;
     int weightA;
     int weightB;
     int samplesA[8];
     int samplesB[8];
 } Decorr;
 

 typedef struct WvChannel {
     int median[3];
     int slow_level, error_limit;
     int bitrate_acc, bitrate_delta;
 } WvChannel;
 

 typedef struct WavpackFrameContext {

     AVCodecContext *avctx;

     int frame_flags;

     int stereo, stereo_in;

     int joint;
     uint32_t CRC;
     GetBitContext gb;

     int got_extra_bits;
     uint32_t crc_extra_bits;
     GetBitContext gb_extra_bits;

     int data_size; // in bits
     int samples;
     int terms;
     Decorr decorr[MAX_TERMS];
     int zero, one, zeroes;

     int extra_bits;

     int and, or, shift;

     int post_shift;

     int hybrid, hybrid_bitrate;
     int hybrid_maxclip, hybrid_minclip;

     int float_flag;
     int float_shift;
     int float_max_exp;

     WvChannel ch[2];

     int pos;
     SavedContext sc, extra_sc;

 } WavpackFrameContext;
 
 #define WV_MAX_FRAME_DECODERS 14
 
 typedef struct WavpackContext {
     AVCodecContext *avctx;

     AVFrame frame;

 
     WavpackFrameContext *fdec[WV_MAX_FRAME_DECODERS];
     int fdec_num;
 
     int multichannel;
     int mkv_mode;
     int block;
     int samples;
     int ch_offset;

 } WavpackContext;
 
 // exponent table copied from WavPack source
 static const uint8_t wp_exp2_table [256] = {
     0x00, 0x01, 0x01, 0x02, 0x03, 0x03, 0x04, 0x05, 0x06, 0x06, 0x07, 0x08, 0x08, 0x09, 0x0a, 0x0b,
     0x0b, 0x0c, 0x0d, 0x0e, 0x0e, 0x0f, 0x10, 0x10, 0x11, 0x12, 0x13, 0x13, 0x14, 0x15, 0x16, 0x16,
     0x17, 0x18, 0x19, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1d, 0x1e, 0x1f, 0x20, 0x20, 0x21, 0x22, 0x23,
     0x24, 0x24, 0x25, 0x26, 0x27, 0x28, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2c, 0x2d, 0x2e, 0x2f, 0x30,
     0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3a, 0x3b, 0x3c, 0x3d,
     0x3e, 0x3f, 0x40, 0x41, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x48, 0x49, 0x4a, 0x4b,
     0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a,
     0x5b, 0x5c, 0x5d, 0x5e, 0x5e, 0x5f, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
     0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
     0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x87, 0x88, 0x89, 0x8a,
     0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b,
     0x9c, 0x9d, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad,
     0xaf, 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xbc, 0xbd, 0xbe, 0xbf, 0xc0,
     0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc8, 0xc9, 0xca, 0xcb, 0xcd, 0xce, 0xcf, 0xd0, 0xd2, 0xd3, 0xd4,
     0xd6, 0xd7, 0xd8, 0xd9, 0xdb, 0xdc, 0xdd, 0xde, 0xe0, 0xe1, 0xe2, 0xe4, 0xe5, 0xe6, 0xe8, 0xe9,
     0xea, 0xec, 0xed, 0xee, 0xf0, 0xf1, 0xf2, 0xf4, 0xf5, 0xf6, 0xf8, 0xf9, 0xfa, 0xfc, 0xfd, 0xff
 };
 

 static const uint8_t wp_log2_table [] = {
     0x00, 0x01, 0x03, 0x04, 0x06, 0x07, 0x09, 0x0a, 0x0b, 0x0d, 0x0e, 0x10, 0x11, 0x12, 0x14, 0x15,
     0x16, 0x18, 0x19, 0x1a, 0x1c, 0x1d, 0x1e, 0x20, 0x21, 0x22, 0x24, 0x25, 0x26, 0x28, 0x29, 0x2a,
     0x2c, 0x2d, 0x2e, 0x2f, 0x31, 0x32, 0x33, 0x34, 0x36, 0x37, 0x38, 0x39, 0x3b, 0x3c, 0x3d, 0x3e,
     0x3f, 0x41, 0x42, 0x43, 0x44, 0x45, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4d, 0x4e, 0x4f, 0x50, 0x51,
     0x52, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x5c, 0x5d, 0x5e, 0x5f, 0x60, 0x61, 0x62, 0x63,
     0x64, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x74, 0x75,
     0x76, 0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85,
     0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95,
     0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4,
     0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, 0xb0, 0xb1, 0xb2, 0xb2,
     0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf, 0xc0, 0xc0,
     0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xcb, 0xcb, 0xcc, 0xcd, 0xce,
     0xcf, 0xd0, 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd8, 0xd9, 0xda, 0xdb,
     0xdc, 0xdc, 0xdd, 0xde, 0xdf, 0xe0, 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe4, 0xe5, 0xe6, 0xe7, 0xe7,
     0xe8, 0xe9, 0xea, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xee, 0xef, 0xf0, 0xf1, 0xf1, 0xf2, 0xf3, 0xf4,
     0xf4, 0xf5, 0xf6, 0xf7, 0xf7, 0xf8, 0xf9, 0xf9, 0xfa, 0xfb, 0xfc, 0xfc, 0xfd, 0xfe, 0xff, 0xff
 };
 

 static av_always_inline int wp_exp2(int16_t val)

 {
     int res, neg = 0;
 

     if (val < 0) {

         val = -val;
         neg = 1;
     }
 
     res = wp_exp2_table[val & 0xFF] | 0x100;
     val >>= 8;
     res = (val > 9) ? (res << (val - 9)) : (res >> (9 - val));
     return neg ? -res : res;
 }
 

 static av_always_inline int wp_log2(int32_t val)
 {
     int bits;
 

     if (!val)

         return 0;

     if (val == 1)

         return 256;
     val += val >> 9;
     bits = av_log2(val) + 1;

     if (bits < 9)

         return (bits << 8) + wp_log2_table[(val << (9 - bits)) & 0xFF];
     else
         return (bits << 8) + wp_log2_table[(val >> (bits - 9)) & 0xFF];
 }
 
 #define LEVEL_DECAY(a)  ((a + 0x80) >> 8)
 

 // macros for manipulating median values

 #define GET_MED(n) ((c->median[n] >> 4) + 1)

 #define DEC_MED(n) c->median[n] -= ((c->median[n] + (128 >> n) - 2) / (128 >> n)) * 2
 #define INC_MED(n) c->median[n] += ((c->median[n] + (128 >> n)    ) / (128 >> n)) * 5

 
 // macros for applying weight
 #define UPDATE_WEIGHT_CLIP(weight, delta, samples, in) \

     if (samples && in) { \
         if ((samples ^ in) < 0) { \
             weight -= delta; \
             if (weight < -1024) \
                 weight = -1024; \
         } else { \
             weight += delta; \
             if (weight > 1024) \
                 weight = 1024; \
         } \
     }

 static av_always_inline int get_tail(GetBitContext *gb, int k)

 {
     int p, e, res;
 

     if (k < 1)
         return 0;

     p = av_log2(k);

     e = (1 << (p + 1)) - k - 1;

     res = p ? get_bits(gb, p) : 0;

     if (res >= e)
         res = (res << 1) - e + get_bits1(gb);

     return res;
 }
 

 static void update_error_limit(WavpackFrameContext *ctx)

 {
     int i, br[2], sl[2];
 

     for (i = 0; i <= ctx->stereo_in; i++) {

         ctx->ch[i].bitrate_acc += ctx->ch[i].bitrate_delta;
         br[i] = ctx->ch[i].bitrate_acc >> 16;
         sl[i] = LEVEL_DECAY(ctx->ch[i].slow_level);
     }

     if (ctx->stereo_in && ctx->hybrid_bitrate) {

         int balance = (sl[1] - sl[0] + br[1] + 1) >> 1;

         if (balance > br[0]) {

             br[1] = br[0] << 1;
             br[0] = 0;

         } else if (-balance > br[0]) {

             br[0] <<= 1;
             br[1] = 0;

         } else {

             br[1] = br[0] + balance;
             br[0] = br[0] - balance;
         }
     }

     for (i = 0; i <= ctx->stereo_in; i++) {
         if (ctx->hybrid_bitrate) {
             if (sl[i] - br[i] > -0x100)

                 ctx->ch[i].error_limit = wp_exp2(sl[i] - br[i] + 0x100);
             else
                 ctx->ch[i].error_limit = 0;

         } else {

             ctx->ch[i].error_limit = wp_exp2(br[i]);
         }
     }
 }
 

 static int wv_get_value(WavpackFrameContext *ctx, GetBitContext *gb,
                         int channel, int *last)

 {
     int t, t2;
     int sign, base, add, ret;

     WvChannel *c = &ctx->ch[channel];

 
     *last = 0;
 

     if ((ctx->ch[0].median[0] < 2U) && (ctx->ch[1].median[0] < 2U) &&
         !ctx->zero && !ctx->one) {
         if (ctx->zeroes) {

             ctx->zeroes--;

             if (ctx->zeroes) {

                 c->slow_level -= LEVEL_DECAY(c->slow_level);

                 return 0;

             }

         } else {

             t = get_unary_0_33(gb);

             if (t >= 2) {
                 if (get_bits_left(gb) < t - 1)

                     goto error;
                 t = get_bits(gb, t - 1) | (1 << (t-1));

             } else {
                 if (get_bits_left(gb) < 0)

                     goto error;
             }

             ctx->zeroes = t;

             if (ctx->zeroes) {

                 memset(ctx->ch[0].median, 0, sizeof(ctx->ch[0].median));
                 memset(ctx->ch[1].median, 0, sizeof(ctx->ch[1].median));
                 c->slow_level -= LEVEL_DECAY(c->slow_level);

                 return 0;
             }
         }
     }
 

     if (ctx->zero) {

         t = 0;
         ctx->zero = 0;

     } else {

         t = get_unary_0_33(gb);

         if (get_bits_left(gb) < 0)

             goto error;

         if (t == 16) {

             t2 = get_unary_0_33(gb);

             if (t2 < 2) {
                 if (get_bits_left(gb) < 0)

                     goto error;
                 t += t2;

             } else {
                 if (get_bits_left(gb) < t2 - 1)

                     goto error;
                 t += get_bits(gb, t2 - 1) | (1 << (t2 - 1));
             }

         }
 

         if (ctx->one) {
             ctx->one = t & 1;
             t = (t >> 1) + 1;
         } else {
             ctx->one = t & 1;

             t >>= 1;
         }
         ctx->zero = !ctx->one;
     }
 

     if (ctx->hybrid && !channel)

         update_error_limit(ctx);
 

     if (!t) {

         base = 0;

         add  = GET_MED(0) - 1;

         DEC_MED(0);

     } else if (t == 1) {

         base = GET_MED(0);

         add  = GET_MED(1) - 1;

         INC_MED(0);
         DEC_MED(1);

     } else if (t == 2) {

         base = GET_MED(0) + GET_MED(1);

         add  = GET_MED(2) - 1;

         INC_MED(0);
         INC_MED(1);
         DEC_MED(2);

     } else {

         base = GET_MED(0) + GET_MED(1) + GET_MED(2) * (t - 2);

         add  = GET_MED(2) - 1;

         INC_MED(0);
         INC_MED(1);
         INC_MED(2);
     }

     if (!c->error_limit) {

         ret = base + get_tail(gb, add);

         if (get_bits_left(gb) <= 0)
             goto error;

     } else {
         int mid = (base * 2 + add + 1) >> 1;
         while (add > c->error_limit) {
             if (get_bits_left(gb) <= 0)

                 goto error;

             if (get_bits1(gb)) {

                 add -= (mid - base);
                 base = mid;

             } else

                 add = mid - base - 1;

             mid = (base * 2 + add + 1) >> 1;

         }
         ret = mid;
     }

     sign = get_bits1(gb);

     if (ctx->hybrid_bitrate)

         c->slow_level += wp_log2(ret) - LEVEL_DECAY(c->slow_level);

     return sign ? ~ret : ret;

 
 error:
     *last = 1;
     return 0;

 }
 

 static inline int wv_get_value_integer(WavpackFrameContext *s, uint32_t *crc,
                                        int S)

 {
     int bit;
 

     if (s->extra_bits){

         S <<= s->extra_bits;
 

         if (s->got_extra_bits && get_bits_left(&s->gb_extra_bits) >= s->extra_bits) {

             S |= get_bits(&s->gb_extra_bits, s->extra_bits);

             *crc = *crc * 9 + (S & 0xffff) * 3 + ((unsigned)S >> 16);

         }
     }

     bit = (S & s->and) | s->or;

     bit = ((S + bit) << s->shift) - bit;

     if (s->hybrid)

         bit = av_clip(bit, s->hybrid_minclip, s->hybrid_maxclip);

     return bit << s->post_shift;

 }
 

 static float wv_get_value_float(WavpackFrameContext *s, uint32_t *crc, int S)

 {
     union {
         float    f;
         uint32_t u;
     } value;
 
     int sign;
     int exp = s->float_max_exp;
 

     if (s->got_extra_bits) {
         const int max_bits  = 1 + 23 + 8 + 1;

         const int left_bits = get_bits_left(&s->gb_extra_bits);

         if (left_bits + 8 * FF_INPUT_BUFFER_PADDING_SIZE < max_bits)

             return 0.0;
     }
 

     if (S) {

         S <<= s->float_shift;
         sign = S < 0;

         if (sign)

             S = -S;

         if (S >= 0x1000000) {
             if (s->got_extra_bits && get_bits1(&s->gb_extra_bits))

                 S = get_bits(&s->gb_extra_bits, 23);

             else

                 S = 0;
             exp = 255;

         } else if (exp) {

             int shift = 23 - av_log2(S);
             exp = s->float_max_exp;

             if (exp <= shift)

                 shift = --exp;
             exp -= shift;
 

             if (shift) {

                 S <<= shift;

                 if ((s->float_flag & WV_FLT_SHIFT_ONES) ||
                     (s->got_extra_bits && (s->float_flag & WV_FLT_SHIFT_SAME) &&
                      get_bits1(&s->gb_extra_bits))) {

                     S |= (1 << shift) - 1;

                 } else if (s->got_extra_bits &&
                            (s->float_flag & WV_FLT_SHIFT_SENT)) {

                     S |= get_bits(&s->gb_extra_bits, shift);
                 }
             }

         } else {

             exp = s->float_max_exp;
         }
         S &= 0x7fffff;

     } else {

         sign = 0;
         exp = 0;

         if (s->got_extra_bits && (s->float_flag & WV_FLT_ZERO_SENT)) {
             if (get_bits1(&s->gb_extra_bits)) {

                 S = get_bits(&s->gb_extra_bits, 23);

                 if (s->float_max_exp >= 25)

                     exp = get_bits(&s->gb_extra_bits, 8);
                 sign = get_bits1(&s->gb_extra_bits);

             } else {
                 if (s->float_flag & WV_FLT_ZERO_SIGN)

                     sign = get_bits1(&s->gb_extra_bits);
             }
         }
     }
 
     *crc = *crc * 27 + S * 9 + exp * 3 + sign;
 
     value.u = (sign << 31) | (exp << 23) | S;
     return value.f;
 }
 

 static void wv_reset_saved_context(WavpackFrameContext *s)

 {
     s->pos = 0;
     s->sc.crc = s->extra_sc.crc = 0xFFFFFFFF;
 }
 

 static inline int wv_unpack_stereo(WavpackFrameContext *s, GetBitContext *gb,
                                    void *dst, const int type)

 {
     int i, j, count = 0;
     int last, t;

     int A, B, L, L2, R, R2;

     int pos = s->pos;
     uint32_t crc = s->sc.crc;
     uint32_t crc_extra_bits = s->extra_sc.crc;

     int16_t *dst16 = dst;
     int32_t *dst32 = dst;

     float   *dstfl = dst;

     const int channel_pad = s->avctx->channels - 2;

     s->one = s->zero = s->zeroes = 0;

     do {

         L = wv_get_value(s, gb, 0, &last);

         if (last)
             break;

         R = wv_get_value(s, gb, 1, &last);

         if (last)
             break;
         for (i = 0; i < s->terms; i++) {

             t = s->decorr[i].value;

             if (t > 0) {
                 if (t > 8) {
                     if (t & 1) {

                         A = 2 * s->decorr[i].samplesA[0] - s->decorr[i].samplesA[1];
                         B = 2 * s->decorr[i].samplesB[0] - s->decorr[i].samplesB[1];

                     } else {

                         A = (3 * s->decorr[i].samplesA[0] - s->decorr[i].samplesA[1]) >> 1;
                         B = (3 * s->decorr[i].samplesB[0] - s->decorr[i].samplesB[1]) >> 1;
                     }
                     s->decorr[i].samplesA[1] = s->decorr[i].samplesA[0];
                     s->decorr[i].samplesB[1] = s->decorr[i].samplesB[0];
                     j = 0;

                 } else {

                     A = s->decorr[i].samplesA[pos];
                     B = s->decorr[i].samplesB[pos];
                     j = (pos + t) & 7;
                 }

                 if (type != AV_SAMPLE_FMT_S16) {

                     L2 = L + ((s->decorr[i].weightA * (int64_t)A + 512) >> 10);
                     R2 = R + ((s->decorr[i].weightB * (int64_t)B + 512) >> 10);

                 } else {

                     L2 = L + ((s->decorr[i].weightA * A + 512) >> 10);
                     R2 = R + ((s->decorr[i].weightB * B + 512) >> 10);

                 }

                 if (A && L) s->decorr[i].weightA -= ((((L ^ A) >> 30) & 2) - 1) * s->decorr[i].delta;
                 if (B && R) s->decorr[i].weightB -= ((((R ^ B) >> 30) & 2) - 1) * s->decorr[i].delta;

                 s->decorr[i].samplesA[j] = L = L2;
                 s->decorr[i].samplesB[j] = R = R2;

             } else if (t == -1) {
                 if (type != AV_SAMPLE_FMT_S16)

                     L2 = L + ((s->decorr[i].weightA * (int64_t)s->decorr[i].samplesA[0] + 512) >> 10);
                 else
                     L2 = L + ((s->decorr[i].weightA * s->decorr[i].samplesA[0] + 512) >> 10);

                 UPDATE_WEIGHT_CLIP(s->decorr[i].weightA, s->decorr[i].delta, s->decorr[i].samplesA[0], L);
                 L = L2;

                 if (type != AV_SAMPLE_FMT_S16)

                     R2 = R + ((s->decorr[i].weightB * (int64_t)L2 + 512) >> 10);
                 else
                     R2 = R + ((s->decorr[i].weightB * L2 + 512) >> 10);

                 UPDATE_WEIGHT_CLIP(s->decorr[i].weightB, s->decorr[i].delta, L2, R);
                 R = R2;
                 s->decorr[i].samplesA[0] = R;

             } else {
                 if (type != AV_SAMPLE_FMT_S16)

                     R2 = R + ((s->decorr[i].weightB * (int64_t)s->decorr[i].samplesB[0] + 512) >> 10);
                 else
                     R2 = R + ((s->decorr[i].weightB * s->decorr[i].samplesB[0] + 512) >> 10);

                 UPDATE_WEIGHT_CLIP(s->decorr[i].weightB, s->decorr[i].delta, s->decorr[i].samplesB[0], R);
                 R = R2;
 

                 if (t == -3) {

                     R2 = s->decorr[i].samplesA[0];
                     s->decorr[i].samplesA[0] = R;
                 }
 

                 if (type != AV_SAMPLE_FMT_S16)

                     L2 = L + ((s->decorr[i].weightA * (int64_t)R2 + 512) >> 10);
                 else
                     L2 = L + ((s->decorr[i].weightA * R2 + 512) >> 10);

                 UPDATE_WEIGHT_CLIP(s->decorr[i].weightA, s->decorr[i].delta, R2, L);
                 L = L2;
                 s->decorr[i].samplesB[0] = L;
             }
         }
         pos = (pos + 1) & 7;

         if (s->joint)

             L += (R -= (L >> 1));
         crc = (crc * 3 + L) * 3 + R;

         if (type == AV_SAMPLE_FMT_FLT) {

             *dstfl++ = wv_get_value_float(s, &crc_extra_bits, L);
             *dstfl++ = wv_get_value_float(s, &crc_extra_bits, R);

             dstfl += channel_pad;

         } else if (type == AV_SAMPLE_FMT_S32) {

             *dst32++ = wv_get_value_integer(s, &crc_extra_bits, L);
             *dst32++ = wv_get_value_integer(s, &crc_extra_bits, R);

             dst32 += channel_pad;

         } else {
             *dst16++ = wv_get_value_integer(s, &crc_extra_bits, L);
             *dst16++ = wv_get_value_integer(s, &crc_extra_bits, R);

             dst16 += channel_pad;

         }

         count++;

     } while (!last && count < s->samples);

     wv_reset_saved_context(s);
     if (crc != s->CRC) {
         av_log(s->avctx, AV_LOG_ERROR, "CRC error\n");
         return -1;
     }
     if (s->got_extra_bits && crc_extra_bits != s->crc_extra_bits) {
         av_log(s->avctx, AV_LOG_ERROR, "Extra bits CRC error\n");
         return -1;
     }

     return count * 2;
 }
 

 static inline int wv_unpack_mono(WavpackFrameContext *s, GetBitContext *gb,
                                  void *dst, const int type)

 {
     int i, j, count = 0;
     int last, t;

     int A, S, T;

     int pos = s->pos;
     uint32_t crc = s->sc.crc;
     uint32_t crc_extra_bits = s->extra_sc.crc;

     int16_t *dst16 = dst;
     int32_t *dst32 = dst;

     float   *dstfl = dst;

     const int channel_stride = s->avctx->channels;

     s->one = s->zero = s->zeroes = 0;

     do {

         T = wv_get_value(s, gb, 0, &last);
         S = 0;

         if (last)
             break;
         for (i = 0; i < s->terms; i++) {

             t = s->decorr[i].value;

             if (t > 8) {
                 if (t & 1)
                     A =  2 * s->decorr[i].samplesA[0] - s->decorr[i].samplesA[1];

                 else
                     A = (3 * s->decorr[i].samplesA[0] - s->decorr[i].samplesA[1]) >> 1;
                 s->decorr[i].samplesA[1] = s->decorr[i].samplesA[0];
                 j = 0;

             } else {

                 A = s->decorr[i].samplesA[pos];
                 j = (pos + t) & 7;
             }

             if (type != AV_SAMPLE_FMT_S16)

                 S = T + ((s->decorr[i].weightA * (int64_t)A + 512) >> 10);
             else
                 S = T + ((s->decorr[i].weightA * A + 512) >> 10);

             if (A && T)
                 s->decorr[i].weightA -= ((((T ^ A) >> 30) & 2) - 1) * s->decorr[i].delta;

             s->decorr[i].samplesA[j] = T = S;
         }
         pos = (pos + 1) & 7;
         crc = crc * 3 + S;

         if (type == AV_SAMPLE_FMT_FLT) {

             *dstfl = wv_get_value_float(s, &crc_extra_bits, S);
             dstfl += channel_stride;

         } else if (type == AV_SAMPLE_FMT_S32) {

             *dst32 = wv_get_value_integer(s, &crc_extra_bits, S);
             dst32 += channel_stride;

         } else {

             *dst16 = wv_get_value_integer(s, &crc_extra_bits, S);
             dst16 += channel_stride;
         }

         count++;

     } while (!last && count < s->samples);

     wv_reset_saved_context(s);
     if (crc != s->CRC) {
         av_log(s->avctx, AV_LOG_ERROR, "CRC error\n");
         return -1;
     }
     if (s->got_extra_bits && crc_extra_bits != s->crc_extra_bits) {
         av_log(s->avctx, AV_LOG_ERROR, "Extra bits CRC error\n");
         return -1;
     }

     return count;
 }
 

 static av_cold int wv_alloc_frame_context(WavpackContext *c)
 {
 

     if (c->fdec_num == WV_MAX_FRAME_DECODERS)

         return -1;
 
     c->fdec[c->fdec_num] = av_mallocz(sizeof(**c->fdec));

     if (!c->fdec[c->fdec_num])

         return -1;
     c->fdec_num++;
     c->fdec[c->fdec_num - 1]->avctx = c->avctx;
     wv_reset_saved_context(c->fdec[c->fdec_num - 1]);
 
     return 0;
 }
 

 static av_cold int wavpack_decode_init(AVCodecContext *avctx)

 {
     WavpackContext *s = avctx->priv_data;
 
     s->avctx = avctx;

     if (avctx->bits_per_coded_sample <= 16)

         avctx->sample_fmt = AV_SAMPLE_FMT_S16;

     else

         avctx->sample_fmt = AV_SAMPLE_FMT_S32;

     if (avctx->channels <= 2 && !avctx->channel_layout)
         avctx->channel_layout = (avctx->channels == 2) ? AV_CH_LAYOUT_STEREO :
                                                          AV_CH_LAYOUT_MONO;

     s->multichannel = avctx->channels > 2;
     /* lavf demuxer does not provide extradata, Matroska stores 0x403
        there, use this to detect decoding mode for multichannel */
     s->mkv_mode = 0;

     if (s->multichannel && avctx->extradata && avctx->extradata_size == 2) {

         int ver = AV_RL16(avctx->extradata);

         if (ver >= 0x402 && ver <= 0x410)

             s->mkv_mode = 1;
     }
 
     s->fdec_num = 0;

     avcodec_get_frame_defaults(&s->frame);
     avctx->coded_frame = &s->frame;
 

     return 0;
 }
 

 static av_cold int wavpack_decode_end(AVCodecContext *avctx)

 {
     WavpackContext *s = avctx->priv_data;

     int i;
 

     for (i = 0; i < s->fdec_num; i++)

         av_freep(&s->fdec[i]);
     s->fdec_num = 0;
 
     return 0;
 }
 
 static int wavpack_decode_block(AVCodecContext *avctx, int block_no,

                                 void *data, int *got_frame_ptr,

                                 const uint8_t *buf, int buf_size)
 {
     WavpackContext *wc = avctx->priv_data;
     WavpackFrameContext *s;

     void *samples = data;

     int samplecount;

     int got_terms   = 0, got_weights = 0, got_samples = 0,

         got_entropy = 0, got_bs      = 0, got_float   = 0, got_hybrid = 0;

     const uint8_t *orig_buf = buf;
     const uint8_t *buf_end  = buf + buf_size;

     int i, j, id, size, ssize, weights, t;

     int bpp, chan, chmask, orig_bpp;

     if (buf_size == 0) {

         *got_frame_ptr = 0;

         return 0;
     }

     if (block_no >= wc->fdec_num && wv_alloc_frame_context(wc) < 0) {

         av_log(avctx, AV_LOG_ERROR, "Error creating frame decode context\n");

         return AVERROR_INVALIDDATA;

     }
 
     s = wc->fdec[block_no];

     if (!s) {

         av_log(avctx, AV_LOG_ERROR, "Context for block %d is not present\n", block_no);

         return AVERROR_INVALIDDATA;

     }
 

     memset(s->decorr, 0, MAX_TERMS * sizeof(Decorr));
     memset(s->ch, 0, sizeof(s->ch));
     s->extra_bits = 0;
     s->and = s->or = s->shift = 0;
     s->got_extra_bits = 0;

     if (!wc->mkv_mode) {

         s->samples = AV_RL32(buf); buf += 4;

         if (s->samples != wc->samples)
             return AVERROR_INVALIDDATA;
 

         if (!s->samples) {

             *got_frame_ptr = 0;

             return 0;

         }

     } else {

         s->samples = wc->samples;
     }

     s->frame_flags = AV_RL32(buf); buf += 4;

     bpp = av_get_bytes_per_sample(avctx->sample_fmt);

     samples = (uint8_t*)samples + bpp * wc->ch_offset;

     orig_bpp = ((s->frame_flags & 0x03) + 1) << 3;

     s->stereo         = !(s->frame_flags & WV_MONO);
     s->stereo_in      =  (s->frame_flags & WV_FALSE_STEREO) ? 0 : s->stereo;
     s->joint          =   s->frame_flags & WV_JOINT_STEREO;
     s->hybrid         =   s->frame_flags & WV_HYBRID_MODE;
     s->hybrid_bitrate =   s->frame_flags & WV_HYBRID_BITRATE;

     s->post_shift     = bpp * 8 - orig_bpp + ((s->frame_flags >> 13) & 0x1f);

     s->hybrid_maxclip = (( 1LL << (orig_bpp - 1)) - 1);
     s->hybrid_minclip = ((-1LL << (orig_bpp - 1)));

     s->CRC            = AV_RL32(buf); buf += 4;
     if (wc->mkv_mode)

         buf += 4; //skip block size;
 
     wc->ch_offset += 1 + s->stereo;

     // parse metadata blocks

     while (buf < buf_end) {
         id   = *buf++;

         size = *buf++;

         if (id & WP_IDF_LONG) {

             size |= (*buf++) << 8;
             size |= (*buf++) << 16;
         }
         size <<= 1; // size is specified in words
         ssize = size;

         if (id & WP_IDF_ODD)
             size--;
         if (size < 0) {

             av_log(avctx, AV_LOG_ERROR, "Got incorrect block %02X with size %i\n", id, size);
             break;
         }

         if (buf + ssize > buf_end) {

             av_log(avctx, AV_LOG_ERROR, "Block size %i is out of bounds\n", size);
             break;
         }

         if (id & WP_IDF_IGNORE) {

             buf += ssize;
             continue;
         }

         switch (id & WP_IDF_MASK) {

         case WP_ID_DECTERMS:

             if (size > MAX_TERMS) {

                 av_log(avctx, AV_LOG_ERROR, "Too many decorrelation terms\n");

                 s->terms = 0;

                 buf += ssize;
                 continue;
             }

             s->terms = size;

             for (i = 0; i < s->terms; i++) {

                 s->decorr[s->terms - i - 1].value = (*buf & 0x1F) - 5;
                 s->decorr[s->terms - i - 1].delta = *buf >> 5;
                 buf++;
             }
             got_terms = 1;
             break;
         case WP_ID_DECWEIGHTS:

             if (!got_terms) {

                 av_log(avctx, AV_LOG_ERROR, "No decorrelation terms met\n");
                 continue;
             }

             weights = size >> s->stereo_in;

             if (weights > MAX_TERMS || weights > s->terms) {

                 av_log(avctx, AV_LOG_ERROR, "Too many decorrelation weights\n");
                 buf += ssize;
                 continue;
             }

             for (i = 0; i < weights; i++) {

                 t = (int8_t)(*buf++);
                 s->decorr[s->terms - i - 1].weightA = t << 3;

                 if (s->decorr[s->terms - i - 1].weightA > 0)
                     s->decorr[s->terms - i - 1].weightA +=
                             (s->decorr[s->terms - i - 1].weightA + 64) >> 7;
                 if (s->stereo_in) {

                     t = (int8_t)(*buf++);
                     s->decorr[s->terms - i - 1].weightB = t << 3;

                     if (s->decorr[s->terms - i - 1].weightB > 0)
                         s->decorr[s->terms - i - 1].weightB +=
                                 (s->decorr[s->terms - i - 1].weightB + 64) >> 7;

                 }
             }
             got_weights = 1;
             break;
         case WP_ID_DECSAMPLES:

             if (!got_terms) {

                 av_log(avctx, AV_LOG_ERROR, "No decorrelation terms met\n");
                 continue;
             }
             t = 0;

             for (i = s->terms - 1; (i >= 0) && (t < size); i--) {

                 if (s->decorr[i].value > 8) {

                     s->decorr[i].samplesA[0] = wp_exp2(AV_RL16(buf)); buf += 2;
                     s->decorr[i].samplesA[1] = wp_exp2(AV_RL16(buf)); buf += 2;

                     if (s->stereo_in) {

                         s->decorr[i].samplesB[0] = wp_exp2(AV_RL16(buf)); buf += 2;
                         s->decorr[i].samplesB[1] = wp_exp2(AV_RL16(buf)); buf += 2;

                         t += 4;
                     }
                     t += 4;

                 } else if (s->decorr[i].value < 0) {

                     s->decorr[i].samplesA[0] = wp_exp2(AV_RL16(buf)); buf += 2;
                     s->decorr[i].samplesB[0] = wp_exp2(AV_RL16(buf)); buf += 2;

                     t += 4;

                 } else {
                     for (j = 0; j < s->decorr[i].value; j++) {

                         s->decorr[i].samplesA[j] = wp_exp2(AV_RL16(buf)); buf += 2;

                         if (s->stereo_in) {

                             s->decorr[i].samplesB[j] = wp_exp2(AV_RL16(buf)); buf += 2;

                         }

                     }

                     t += s->decorr[i].value * 2 * (s->stereo_in + 1);

                 }
             }
             got_samples = 1;
             break;
         case WP_ID_ENTROPY:

             if (size != 6 * (s->stereo_in + 1)) {
                 av_log(avctx, AV_LOG_ERROR, "Entropy vars size should be %i, "
                        "got %i", 6 * (s->stereo_in + 1), size);

                 buf += ssize;
                 continue;
             }

             for (j = 0; j <= s->stereo_in; j++) {
                 for (i = 0; i < 3; i++) {

                     s->ch[j].median[i] = wp_exp2(AV_RL16(buf));
                     buf += 2;
                 }

             }
             got_entropy = 1;
             break;

         case WP_ID_HYBRID:

             if (s->hybrid_bitrate) {
                 for (i = 0; i <= s->stereo_in; i++) {

                     s->ch[i].slow_level = wp_exp2(AV_RL16(buf));
                     buf += 2;
                     size -= 2;
                 }
             }

             for (i = 0; i < (s->stereo_in + 1); i++) {

                 s->ch[i].bitrate_acc = AV_RL16(buf) << 16;
                 buf += 2;
                 size -= 2;
             }

             if (size > 0) {
                 for (i = 0; i < (s->stereo_in + 1); i++) {

                     s->ch[i].bitrate_delta = wp_exp2((int16_t)AV_RL16(buf));
                     buf += 2;
                 }

             } else {
                 for (i = 0; i < (s->stereo_in + 1); i++)

                     s->ch[i].bitrate_delta = 0;
             }
             got_hybrid = 1;
             break;

         case WP_ID_INT32INFO:

             if (size != 4) {

                 av_log(avctx, AV_LOG_ERROR, "Invalid INT32INFO, size = %i, sent_bits = %i\n", size, *buf);
                 buf += ssize;
                 continue;
             }

             if (buf[0])

                 s->extra_bits = buf[0];

             else if (buf[1])

                 s->shift = buf[1];

             else if (buf[2]){

                 s->and = s->or = 1;
                 s->shift = buf[2];

             } else if(buf[3]) {
                 s->and   = 1;

                 s->shift = buf[3];
             }

             /* original WavPack decoder forces 32-bit lossy sound to be treated
              * as 24-bit one in order to have proper clipping
              */
             if (s->hybrid && bpp == 4 && s->post_shift < 8 && s->shift > 8) {
                 s->post_shift += 8;
                 s->shift      -= 8;
                 s->hybrid_maxclip >>= 8;
                 s->hybrid_minclip >>= 8;
             }

             buf += 4;
             break;

         case WP_ID_FLOATINFO:

             if (size != 4) {

                 av_log(avctx, AV_LOG_ERROR, "Invalid FLOATINFO, size = %i\n", size);
                 buf += ssize;
                 continue;
             }

             s->float_flag    = buf[0];
             s->float_shift   = buf[1];

             s->float_max_exp = buf[2];
             buf += 4;
             got_float = 1;
             break;

         case WP_ID_DATA:

             s->sc.offset = buf - orig_buf;

             s->sc.size   = size * 8;

             init_get_bits(&s->gb, buf, size * 8);
             s->data_size = size * 8;
             buf += size;
             got_bs = 1;
             break;

         case WP_ID_EXTRABITS:

             if (size <= 4) {
                 av_log(avctx, AV_LOG_ERROR, "Invalid EXTRABITS, size = %i\n",
                        size);

                 buf += size;
                 continue;
             }

             s->extra_sc.offset = buf - orig_buf;

             s->extra_sc.size   = size * 8;

             init_get_bits(&s->gb_extra_bits, buf, size * 8);
             s->crc_extra_bits = get_bits_long(&s->gb_extra_bits, 32);
             buf += size;
             s->got_extra_bits = 1;
             break;

         case WP_ID_CHANINFO:

             if (size <= 1) {

                 av_log(avctx, AV_LOG_ERROR, "Insufficient channel information\n");

                 return AVERROR_INVALIDDATA;

             }
             chan = *buf++;

             switch (size - 2) {
             case 0: chmask = *buf;         break;
             case 1: chmask = AV_RL16(buf); break;
             case 2: chmask = AV_RL24(buf); break;
             case 3: chmask = AV_RL32(buf); break;

             case 5:
                 chan |= (buf[1] & 0xF) << 8;
                 chmask = AV_RL24(buf + 2);
                 break;
             default:

                 av_log(avctx, AV_LOG_ERROR, "Invalid channel info size %d\n",
                        size);
                 chan   = avctx->channels;

                 chmask = avctx->channel_layout;
             }

             if (chan != avctx->channels) {

                 av_log(avctx, AV_LOG_ERROR,
                        "Block reports total %d channels, "
                        "decoder believes it's %d channels\n",
                        chan, avctx->channels);
                 return AVERROR_INVALIDDATA;

             }

             if (!avctx->channel_layout)

                 avctx->channel_layout = chmask;
             buf += size - 1;
             break;

         default:
             buf += size;
         }

         if (id & WP_IDF_ODD)
             buf++;

     }

     if (!got_terms) {
         av_log(avctx, AV_LOG_ERROR, "No block with decorrelation terms\n");

         return AVERROR_INVALIDDATA;

     }
     if (!got_weights) {
         av_log(avctx, AV_LOG_ERROR, "No block with decorrelation weights\n");

         return AVERROR_INVALIDDATA;

     }
     if (!got_samples) {
         av_log(avctx, AV_LOG_ERROR, "No block with decorrelation samples\n");

         return AVERROR_INVALIDDATA;

     }
     if (!got_entropy) {
         av_log(avctx, AV_LOG_ERROR, "No block with entropy info\n");

         return AVERROR_INVALIDDATA;

     }
     if (s->hybrid && !got_hybrid) {
         av_log(avctx, AV_LOG_ERROR, "Hybrid config not found\n");

         return AVERROR_INVALIDDATA;

     }
     if (!got_bs) {
         av_log(avctx, AV_LOG_ERROR, "Packed samples not found\n");

         return AVERROR_INVALIDDATA;

     }
     if (!got_float && avctx->sample_fmt == AV_SAMPLE_FMT_FLT) {
         av_log(avctx, AV_LOG_ERROR, "Float information not found\n");

         return AVERROR_INVALIDDATA;

     }
     if (s->got_extra_bits && avctx->sample_fmt != AV_SAMPLE_FMT_FLT) {
         const int size   = get_bits_left(&s->gb_extra_bits);
         const int wanted = s->samples * s->extra_bits << s->stereo_in;
         if (size < wanted) {
             av_log(avctx, AV_LOG_ERROR, "Too small EXTRABITS\n");
             s->got_extra_bits = 0;

         }

     }

     if (s->stereo_in) {
         if (avctx->sample_fmt == AV_SAMPLE_FMT_S16)

             samplecount = wv_unpack_stereo(s, &s->gb, samples, AV_SAMPLE_FMT_S16);

         else if (avctx->sample_fmt == AV_SAMPLE_FMT_S32)

             samplecount = wv_unpack_stereo(s, &s->gb, samples, AV_SAMPLE_FMT_S32);

         else

             samplecount = wv_unpack_stereo(s, &s->gb, samples, AV_SAMPLE_FMT_FLT);

 
         if (samplecount < 0)

             return samplecount;

         samplecount >>= 1;

     } else {

         const int channel_stride = avctx->channels;
 

         if (avctx->sample_fmt == AV_SAMPLE_FMT_S16)

             samplecount = wv_unpack_mono(s, &s->gb, samples, AV_SAMPLE_FMT_S16);

         else if (avctx->sample_fmt == AV_SAMPLE_FMT_S32)

             samplecount = wv_unpack_mono(s, &s->gb, samples, AV_SAMPLE_FMT_S32);

         else

             samplecount = wv_unpack_mono(s, &s->gb, samples, AV_SAMPLE_FMT_FLT);

         if (samplecount < 0)

             return samplecount;

         if (s->stereo && avctx->sample_fmt == AV_SAMPLE_FMT_S16) {

             int16_t *dst = (int16_t*)samples + 1;
             int16_t *src = (int16_t*)samples;

             int cnt = samplecount;

             while (cnt--) {

                 *dst = *src;
                 src += channel_stride;
                 dst += channel_stride;

             }

         } else if (s->stereo && avctx->sample_fmt == AV_SAMPLE_FMT_S32) {

             int32_t *dst = (int32_t*)samples + 1;
             int32_t *src = (int32_t*)samples;

             int cnt = samplecount;

             while (cnt--) {

                 *dst = *src;
                 src += channel_stride;
                 dst += channel_stride;

             }

         } else if (s->stereo) {

             float *dst = (float*)samples + 1;
             float *src = (float*)samples;

             int cnt = samplecount;

             while (cnt--) {

                 *dst = *src;
                 src += channel_stride;
                 dst += channel_stride;
             }
         }
     }
 

     *got_frame_ptr = 1;

 
     return samplecount * bpp;
 }
 

 static void wavpack_decode_flush(AVCodecContext *avctx)
 {
     WavpackContext *s = avctx->priv_data;
     int i;
 
     for (i = 0; i < s->fdec_num; i++)
         wv_reset_saved_context(s->fdec[i]);
 }
 

 static int wavpack_decode_frame(AVCodecContext *avctx, void *data,
                                 int *got_frame_ptr, AVPacket *avpkt)

 {

     WavpackContext *s  = avctx->priv_data;

     const uint8_t *buf = avpkt->data;

     int buf_size       = avpkt->size;

     int frame_size, ret, frame_flags;

     int samplecount = 0;
 

     if (avpkt->size < 12 + s->multichannel * 4)
         return AVERROR_INVALIDDATA;
 

     s->block     = 0;

     s->ch_offset = 0;
 

     /* determine number of samples */

     if (s->mkv_mode) {

         s->samples  = AV_RL32(buf); buf += 4;
         frame_flags = AV_RL32(buf);

     } else {

         if (s->multichannel) {
             s->samples  = AV_RL32(buf + 4);
             frame_flags = AV_RL32(buf + 8);
         } else {
             s->samples  = AV_RL32(buf);
             frame_flags = AV_RL32(buf + 4);
         }

     }
     if (s->samples <= 0) {
         av_log(avctx, AV_LOG_ERROR, "Invalid number of samples: %d\n",
                s->samples);

         return AVERROR_INVALIDDATA;

     }
 

     if (frame_flags & 0x80) {
         avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
     } else if ((frame_flags & 0x03) <= 1) {
         avctx->sample_fmt = AV_SAMPLE_FMT_S16;
     } else {
         avctx->sample_fmt = AV_SAMPLE_FMT_S32;
     }
 

     /* get output buffer */
     s->frame.nb_samples = s->samples;
     if ((ret = avctx->get_buffer(avctx, &s->frame)) < 0) {
         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
         return ret;

     }

     while (buf_size > 0) {
         if (!s->multichannel) {

             frame_size = buf_size;

         } else {
             if (!s->mkv_mode) {

                 frame_size = AV_RL32(buf) - 12; buf += 4; buf_size -= 4;

             } else {
                 if (buf_size < 12) //MKV files can have zero flags after last block

                     break;
                 frame_size = AV_RL32(buf + 8) + 12;

             }

         }

         if (frame_size < 0 || frame_size > buf_size) {
             av_log(avctx, AV_LOG_ERROR, "Block %d has invalid size (size %d "
                    "vs. %d bytes left)\n", s->block, frame_size, buf_size);

             wavpack_decode_flush(avctx);

             return AVERROR_INVALIDDATA;

         }

         if ((samplecount = wavpack_decode_block(avctx, s->block,
                                                 s->frame.data[0], got_frame_ptr,
                                                 buf, frame_size)) < 0) {

             wavpack_decode_flush(avctx);

             return samplecount;

         }

         s->block++;
         buf += frame_size; buf_size -= frame_size;

     }

     if (*got_frame_ptr)
         *(AVFrame *)data = s->frame;
 
     return avpkt->size;

 }
 

 AVCodec ff_wavpack_decoder = {

     .name           = "wavpack",
     .type           = AVMEDIA_TYPE_AUDIO,
     .id             = CODEC_ID_WAVPACK,
     .priv_data_size = sizeof(WavpackContext),
     .init           = wavpack_decode_init,
     .close          = wavpack_decode_end,
     .decode         = wavpack_decode_frame,

     .flush          = wavpack_decode_flush,

     .capabilities   = CODEC_CAP_SUBFRAMES | CODEC_CAP_DR1,

     .long_name      = NULL_IF_CONFIG_SMALL("WavPack"),

 };