/*
  * Smacker decoder
  * Copyright (c) 2006 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
  */
 
 /**

  * @file

  * Smacker decoder
  */
 
 /*
  * Based on http://wiki.multimedia.cx/index.php?title=Smacker
  */
 
 #include <stdio.h>
 #include <stdlib.h>
 

 #include "libavutil/channel_layout.h"

 #include "avcodec.h"

 #include "internal.h"

 #include "mathops.h"

 #define BITSTREAM_READER_LE

 #include "get_bits.h"

 #include "bytestream.h"

 
 #define SMKTREE_BITS 9
 #define SMK_NODE 0x80000000
 
 /*
  * Decoder context
  */
 typedef struct SmackVContext {
     AVCodecContext *avctx;
     AVFrame pic;
 
     int *mmap_tbl, *mclr_tbl, *full_tbl, *type_tbl;
     int mmap_last[3], mclr_last[3], full_last[3], type_last[3];
 } SmackVContext;
 
 /**
  * Context used for code reconstructing
  */
 typedef struct HuffContext {
     int length;
     int maxlength;
     int current;
     uint32_t *bits;
     int *lengths;
     int *values;
 } HuffContext;
 
 /* common parameters used for decode_bigtree */
 typedef struct DBCtx {
     VLC *v1, *v2;
     int *recode1, *recode2;
     int escapes[3];
     int *last;
     int lcur;
 } DBCtx;
 
 /* possible runs of blocks */
 static const int block_runs[64] = {
       1,    2,    3,    4,    5,    6,    7,    8,
       9,   10,   11,   12,   13,   14,   15,   16,
      17,   18,   19,   20,   21,   22,   23,   24,
      25,   26,   27,   28,   29,   30,   31,   32,
      33,   34,   35,   36,   37,   38,   39,   40,
      41,   42,   43,   44,   45,   46,   47,   48,
      49,   50,   51,   52,   53,   54,   55,   56,
      57,   58,   59,  128,  256,  512, 1024, 2048 };
 
 enum SmkBlockTypes {
     SMK_BLK_MONO = 0,
     SMK_BLK_FULL = 1,
     SMK_BLK_SKIP = 2,
     SMK_BLK_FILL = 3 };
 
 /**
  * Decode local frame tree
  */
 static int smacker_decode_tree(GetBitContext *gb, HuffContext *hc, uint32_t prefix, int length)
 {

     if(length > 32 || length > 3*SMKTREE_BITS) {

         av_log(NULL, AV_LOG_ERROR, "length too long\n");

         return AVERROR_INVALIDDATA;

     }

     if(!get_bits1(gb)){ //Leaf
         if(hc->current >= 256){
             av_log(NULL, AV_LOG_ERROR, "Tree size exceeded!\n");

             return AVERROR_INVALIDDATA;

         }
         if(length){
             hc->bits[hc->current] = prefix;
             hc->lengths[hc->current] = length;
         } else {
             hc->bits[hc->current] = 0;
             hc->lengths[hc->current] = 0;
         }
         hc->values[hc->current] = get_bits(gb, 8);
         hc->current++;
         if(hc->maxlength < length)
             hc->maxlength = length;
         return 0;
     } else { //Node
         int r;
         length++;
         r = smacker_decode_tree(gb, hc, prefix, length);
         if(r)
             return r;
         return smacker_decode_tree(gb, hc, prefix | (1 << (length - 1)), length);
     }
 }
 
 /**
  * Decode header tree
  */
 static int smacker_decode_bigtree(GetBitContext *gb, HuffContext *hc, DBCtx *ctx)
 {

     if (hc->current + 1 >= hc->length) {
         av_log(NULL, AV_LOG_ERROR, "Tree size exceeded!\n");

         return AVERROR_INVALIDDATA;

     }

     if(!get_bits1(gb)){ //Leaf

         int val, i1, i2;

         i1 = ctx->v1->table ? get_vlc2(gb, ctx->v1->table, SMKTREE_BITS, 3) : 0;
         i2 = ctx->v2->table ? get_vlc2(gb, ctx->v2->table, SMKTREE_BITS, 3) : 0;
         if (i1 < 0 || i2 < 0)

             return AVERROR_INVALIDDATA;

         val = ctx->recode1[i1] | (ctx->recode2[i2] << 8);
         if(val == ctx->escapes[0]) {
             ctx->last[0] = hc->current;
             val = 0;
         } else if(val == ctx->escapes[1]) {
             ctx->last[1] = hc->current;
             val = 0;
         } else if(val == ctx->escapes[2]) {
             ctx->last[2] = hc->current;
             val = 0;
         }
 
         hc->values[hc->current++] = val;
         return 1;
     } else { //Node

         int r = 0, r_new, t;

 
         t = hc->current++;
         r = smacker_decode_bigtree(gb, hc, ctx);
         if(r < 0)
             return r;
         hc->values[t] = SMK_NODE | r;
         r++;

         r_new = smacker_decode_bigtree(gb, hc, ctx);
         if (r_new < 0)
             return r_new;
         return r + r_new;

     }
 }
 
 /**
  * Store large tree as FFmpeg's vlc codes
  */
 static int smacker_decode_header_tree(SmackVContext *smk, GetBitContext *gb, int **recodes, int *last, int size)
 {
     int res;
     HuffContext huff;
     HuffContext tmp1, tmp2;

     VLC vlc[2] = { { 0 } };

     int escapes[3];
     DBCtx ctx;

     int err = 0;

     if(size >= UINT_MAX>>4){ // (((size + 3) >> 2) + 3) << 2 must not overflow
         av_log(smk->avctx, AV_LOG_ERROR, "size too large\n");

         return AVERROR_INVALIDDATA;

     }
 

     tmp1.length = 256;
     tmp1.maxlength = 0;
     tmp1.current = 0;
     tmp1.bits = av_mallocz(256 * 4);
     tmp1.lengths = av_mallocz(256 * sizeof(int));
     tmp1.values = av_mallocz(256 * sizeof(int));
 
     tmp2.length = 256;
     tmp2.maxlength = 0;
     tmp2.current = 0;
     tmp2.bits = av_mallocz(256 * 4);
     tmp2.lengths = av_mallocz(256 * sizeof(int));
     tmp2.values = av_mallocz(256 * sizeof(int));
 
     if(get_bits1(gb)) {

         res = smacker_decode_tree(gb, &tmp1, 0, 0);
         if (res < 0)
             return res;

         skip_bits1(gb);

         if(tmp1.current > 1) {
             res = init_vlc(&vlc[0], SMKTREE_BITS, tmp1.length,
                         tmp1.lengths, sizeof(int), sizeof(int),
                         tmp1.bits, sizeof(uint32_t), sizeof(uint32_t), INIT_VLC_LE);
             if(res < 0) {
                 av_log(smk->avctx, AV_LOG_ERROR, "Cannot build VLC table\n");
                 return AVERROR_INVALIDDATA;
             }

         }

     }
     if (!vlc[0].table) {

         av_log(smk->avctx, AV_LOG_ERROR, "Skipping low bytes tree\n");
     }
     if(get_bits1(gb)){

         res = smacker_decode_tree(gb, &tmp2, 0, 0);
         if (res < 0)
             return res;

         skip_bits1(gb);

         if(tmp2.current > 1) {
             res = init_vlc(&vlc[1], SMKTREE_BITS, tmp2.length,
                         tmp2.lengths, sizeof(int), sizeof(int),
                         tmp2.bits, sizeof(uint32_t), sizeof(uint32_t), INIT_VLC_LE);
             if(res < 0) {
                 av_log(smk->avctx, AV_LOG_ERROR, "Cannot build VLC table\n");
                 return AVERROR_INVALIDDATA;
             }

         }

     }
     if (!vlc[1].table) {

         av_log(smk->avctx, AV_LOG_ERROR, "Skipping high bytes tree\n");
     }
 

     escapes[0]  = get_bits(gb, 16);
     escapes[1]  = get_bits(gb, 16);
     escapes[2]  = get_bits(gb, 16);

 
     last[0] = last[1] = last[2] = -1;
 
     ctx.escapes[0] = escapes[0];
     ctx.escapes[1] = escapes[1];
     ctx.escapes[2] = escapes[2];
     ctx.v1 = &vlc[0];
     ctx.v2 = &vlc[1];
     ctx.recode1 = tmp1.values;
     ctx.recode2 = tmp2.values;
     ctx.last = last;
 

     huff.length = ((size + 3) >> 2) + 4;

     huff.maxlength = 0;
     huff.current = 0;
     huff.values = av_mallocz(huff.length * sizeof(int));
 

     if (smacker_decode_bigtree(gb, &huff, &ctx) < 0)
         err = -1;

     skip_bits1(gb);

     if(ctx.last[0] == -1) ctx.last[0] = huff.current++;
     if(ctx.last[1] == -1) ctx.last[1] = huff.current++;
     if(ctx.last[2] == -1) ctx.last[2] = huff.current++;

     if (ctx.last[0] >= huff.length ||
         ctx.last[1] >= huff.length ||
         ctx.last[2] >= huff.length) {
         av_log(smk->avctx, AV_LOG_ERROR, "Huffman codes out of range\n");

         ctx.last[0] = ctx.last[1] = ctx.last[2] = 1;

         err = AVERROR_INVALIDDATA;

     }

 
     *recodes = huff.values;
 
     if(vlc[0].table)

         ff_free_vlc(&vlc[0]);

     if(vlc[1].table)

         ff_free_vlc(&vlc[1]);

     av_free(tmp1.bits);
     av_free(tmp1.lengths);
     av_free(tmp1.values);
     av_free(tmp2.bits);
     av_free(tmp2.lengths);
     av_free(tmp2.values);
 

     return err;

 }
 
 static int decode_header_trees(SmackVContext *smk) {
     GetBitContext gb;
     int mmap_size, mclr_size, full_size, type_size;
 

     mmap_size = AV_RL32(smk->avctx->extradata);
     mclr_size = AV_RL32(smk->avctx->extradata + 4);
     full_size = AV_RL32(smk->avctx->extradata + 8);
     type_size = AV_RL32(smk->avctx->extradata + 12);

 
     init_get_bits(&gb, smk->avctx->extradata + 16, (smk->avctx->extradata_size - 16) * 8);
 
     if(!get_bits1(&gb)) {
         av_log(smk->avctx, AV_LOG_INFO, "Skipping MMAP tree\n");
         smk->mmap_tbl = av_malloc(sizeof(int) * 2);
         smk->mmap_tbl[0] = 0;
         smk->mmap_last[0] = smk->mmap_last[1] = smk->mmap_last[2] = 1;
     } else {

         if (smacker_decode_header_tree(smk, &gb, &smk->mmap_tbl, smk->mmap_last, mmap_size))

             return AVERROR_INVALIDDATA;

     }

     if(!get_bits1(&gb)) {

         av_log(smk->avctx, AV_LOG_INFO, "Skipping MCLR tree\n");
         smk->mclr_tbl = av_malloc(sizeof(int) * 2);
         smk->mclr_tbl[0] = 0;
         smk->mclr_last[0] = smk->mclr_last[1] = smk->mclr_last[2] = 1;
     } else {

         if (smacker_decode_header_tree(smk, &gb, &smk->mclr_tbl, smk->mclr_last, mclr_size))

             return AVERROR_INVALIDDATA;

     }

     if(!get_bits1(&gb)) {

         av_log(smk->avctx, AV_LOG_INFO, "Skipping FULL tree\n");
         smk->full_tbl = av_malloc(sizeof(int) * 2);
         smk->full_tbl[0] = 0;
         smk->full_last[0] = smk->full_last[1] = smk->full_last[2] = 1;
     } else {

         if (smacker_decode_header_tree(smk, &gb, &smk->full_tbl, smk->full_last, full_size))

             return AVERROR_INVALIDDATA;

     }

     if(!get_bits1(&gb)) {

         av_log(smk->avctx, AV_LOG_INFO, "Skipping TYPE tree\n");
         smk->type_tbl = av_malloc(sizeof(int) * 2);
         smk->type_tbl[0] = 0;
         smk->type_last[0] = smk->type_last[1] = smk->type_last[2] = 1;
     } else {

         if (smacker_decode_header_tree(smk, &gb, &smk->type_tbl, smk->type_last, type_size))

             return AVERROR_INVALIDDATA;

     }
 
     return 0;
 }
 

 static av_always_inline void last_reset(int *recode, int *last) {

     recode[last[0]] = recode[last[1]] = recode[last[2]] = 0;
 }
 
 /* get code and update history */

 static av_always_inline int smk_get_code(GetBitContext *gb, int *recode, int *last) {

     register int *table = recode;

     int v;

 
     while(*table & SMK_NODE) {
         if(get_bits1(gb))
             table += (*table) & (~SMK_NODE);
         table++;
     }
     v = *table;
 
     if(v != recode[last[0]]) {
         recode[last[2]] = recode[last[1]];
         recode[last[1]] = recode[last[0]];
         recode[last[0]] = v;
     }
     return v;
 }
 

 static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
                         AVPacket *avpkt)

 {

     SmackVContext * const smk = avctx->priv_data;

     uint8_t *out;
     uint32_t *pal;

     GetByteContext gb2;

     GetBitContext gb;
     int blocks, blk, bw, bh;

     int i, ret;

     int stride;

     int flags;

     if (avpkt->size <= 769)

         return AVERROR_INVALIDDATA;

     smk->pic.reference = 3;

     smk->pic.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;

     if((ret = avctx->reget_buffer(avctx, &smk->pic)) < 0){

         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");

         return ret;

     }
 
     /* make the palette available on the way out */
     pal = (uint32_t*)smk->pic.data[1];

     bytestream2_init(&gb2, avpkt->data, avpkt->size);
     flags = bytestream2_get_byteu(&gb2);
     smk->pic.palette_has_changed = flags & 1;
     smk->pic.key_frame = !!(flags & 2);

     if(smk->pic.key_frame)

         smk->pic.pict_type = AV_PICTURE_TYPE_I;

     else

         smk->pic.pict_type = AV_PICTURE_TYPE_P;

     for(i = 0; i < 256; i++)

         *pal++ = 0xFFU << 24 | bytestream2_get_be24u(&gb2);

 
     last_reset(smk->mmap_tbl, smk->mmap_last);
     last_reset(smk->mclr_tbl, smk->mclr_last);
     last_reset(smk->full_tbl, smk->full_last);
     last_reset(smk->type_tbl, smk->type_last);

     init_get_bits(&gb, avpkt->data + 769, (avpkt->size - 769) * 8);

 
     blk = 0;
     bw = avctx->width >> 2;
     bh = avctx->height >> 2;
     blocks = bw * bh;
     out = smk->pic.data[0];
     stride = smk->pic.linesize[0];
     while(blk < blocks) {
         int type, run, mode;
         uint16_t pix;
 
         type = smk_get_code(&gb, smk->type_tbl, smk->type_last);
         run = block_runs[(type >> 2) & 0x3F];
         switch(type & 3){
         case SMK_BLK_MONO:
             while(run-- && blk < blocks){
                 int clr, map;
                 int hi, lo;
                 clr = smk_get_code(&gb, smk->mclr_tbl, smk->mclr_last);
                 map = smk_get_code(&gb, smk->mmap_tbl, smk->mmap_last);
                 out = smk->pic.data[0] + (blk / bw) * (stride * 4) + (blk % bw) * 4;
                 hi = clr >> 8;
                 lo = clr & 0xFF;
                 for(i = 0; i < 4; i++) {
                     if(map & 1) out[0] = hi; else out[0] = lo;
                     if(map & 2) out[1] = hi; else out[1] = lo;
                     if(map & 4) out[2] = hi; else out[2] = lo;
                     if(map & 8) out[3] = hi; else out[3] = lo;
                     map >>= 4;
                     out += stride;
                 }
                 blk++;
             }
             break;
         case SMK_BLK_FULL:
             mode = 0;

             if(avctx->codec_tag == MKTAG('S', 'M', 'K', '4')) { // In case of Smacker v4 we have three modes

                 if(get_bits1(&gb)) mode = 1;
                 else if(get_bits1(&gb)) mode = 2;
             }
             while(run-- && blk < blocks){
                 out = smk->pic.data[0] + (blk / bw) * (stride * 4) + (blk % bw) * 4;
                 switch(mode){
                 case 0:
                     for(i = 0; i < 4; i++) {
                         pix = smk_get_code(&gb, smk->full_tbl, smk->full_last);

                         AV_WL16(out+2,pix);

                         pix = smk_get_code(&gb, smk->full_tbl, smk->full_last);

                         AV_WL16(out,pix);

                         out += stride;
                     }
                     break;
                 case 1:
                     pix = smk_get_code(&gb, smk->full_tbl, smk->full_last);
                     out[0] = out[1] = pix & 0xFF;
                     out[2] = out[3] = pix >> 8;
                     out += stride;
                     out[0] = out[1] = pix & 0xFF;
                     out[2] = out[3] = pix >> 8;
                     out += stride;
                     pix = smk_get_code(&gb, smk->full_tbl, smk->full_last);
                     out[0] = out[1] = pix & 0xFF;
                     out[2] = out[3] = pix >> 8;
                     out += stride;
                     out[0] = out[1] = pix & 0xFF;
                     out[2] = out[3] = pix >> 8;
                     out += stride;
                     break;
                 case 2:
                     for(i = 0; i < 2; i++) {
                         uint16_t pix1, pix2;
                         pix2 = smk_get_code(&gb, smk->full_tbl, smk->full_last);

                         pix1 = smk_get_code(&gb, smk->full_tbl, smk->full_last);

                         AV_WL16(out,pix1);
                         AV_WL16(out+2,pix2);

                         out += stride;

                         AV_WL16(out,pix1);
                         AV_WL16(out+2,pix2);

                         out += stride;
                     }
                     break;
                 }
                 blk++;
             }
             break;
         case SMK_BLK_SKIP:
             while(run-- && blk < blocks)
                 blk++;
             break;
         case SMK_BLK_FILL:
             mode = type >> 8;
             while(run-- && blk < blocks){
                 uint32_t col;
                 out = smk->pic.data[0] + (blk / bw) * (stride * 4) + (blk % bw) * 4;
                 col = mode * 0x01010101;
                 for(i = 0; i < 4; i++) {
                     *((uint32_t*)out) = col;
                     out += stride;
                 }
                 blk++;
             }
             break;
         }
 
     }
 

     *got_frame = 1;

     *(AVFrame*)data = smk->pic;
 
     /* always report that the buffer was completely consumed */

     return avpkt->size;

 }
 
 
 
 /*
  *
  * Init smacker decoder
  *
  */

 static av_cold int decode_init(AVCodecContext *avctx)

 {

     SmackVContext * const c = avctx->priv_data;

 
     c->avctx = avctx;
 

     avctx->pix_fmt = AV_PIX_FMT_PAL8;

     avcodec_get_frame_defaults(&c->pic);

 
     /* decode huffman trees from extradata */
     if(avctx->extradata_size < 16){
         av_log(avctx, AV_LOG_ERROR, "Extradata missing!\n");

         return AVERROR(EINVAL);

     }
 

     if (decode_header_trees(c))

         return AVERROR_INVALIDDATA;

 
     return 0;
 }
 
 
 
 /*
  *
  * Uninit smacker decoder
  *
  */

 static av_cold int decode_end(AVCodecContext *avctx)

 {

     SmackVContext * const smk = avctx->priv_data;

     av_freep(&smk->mmap_tbl);
     av_freep(&smk->mclr_tbl);
     av_freep(&smk->full_tbl);
     av_freep(&smk->type_tbl);

 
     if (smk->pic.data[0])
         avctx->release_buffer(avctx, &smk->pic);
 
     return 0;
 }
 
 

 typedef struct SmackerAudioContext {
     AVFrame frame;
 } SmackerAudioContext;
 

 static av_cold int smka_decode_init(AVCodecContext *avctx)

 {

     SmackerAudioContext *s = avctx->priv_data;
 

     if (avctx->channels < 1 || avctx->channels > 2) {
         av_log(avctx, AV_LOG_ERROR, "invalid number of channels\n");
         return AVERROR(EINVAL);
     }

     avctx->channel_layout = (avctx->channels==2) ? AV_CH_LAYOUT_STEREO : AV_CH_LAYOUT_MONO;

     avctx->sample_fmt = avctx->bits_per_coded_sample == 8 ? AV_SAMPLE_FMT_U8 : AV_SAMPLE_FMT_S16;

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

     return 0;
 }
 
 /**
  * Decode Smacker audio data
  */

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

 {

     SmackerAudioContext *s = avctx->priv_data;

     const uint8_t *buf = avpkt->data;
     int buf_size = avpkt->size;

     GetBitContext gb;

     HuffContext h[4] = { { 0 } };
     VLC vlc[4]       = { { 0 } };

     int16_t *samples;
     uint8_t *samples8;

     int val;

     int i, res, ret;

     int unp_size;
     int bits, stereo;
     int pred[2] = {0, 0};
 

     if (buf_size <= 4) {
         av_log(avctx, AV_LOG_ERROR, "packet is too small\n");
         return AVERROR(EINVAL);
     }
 

     unp_size = AV_RL32(buf);

     if (unp_size > (1U<<24)) {
         av_log(avctx, AV_LOG_ERROR, "packet is too big\n");
         return AVERROR_INVALIDDATA;
     }
 

     init_get_bits(&gb, buf + 4, (buf_size - 4) * 8);
 
     if(!get_bits1(&gb)){
         av_log(avctx, AV_LOG_INFO, "Sound: no data\n");

         *got_frame_ptr = 0;

         return 1;
     }
     stereo = get_bits1(&gb);
     bits = get_bits1(&gb);

     if (stereo ^ (avctx->channels != 1)) {
         av_log(avctx, AV_LOG_ERROR, "channels mismatch\n");
         return AVERROR(EINVAL);
     }
     if (bits && avctx->sample_fmt == AV_SAMPLE_FMT_U8) {
         av_log(avctx, AV_LOG_ERROR, "sample format mismatch\n");
         return AVERROR(EINVAL);
     }

     /* get output buffer */
     s->frame.nb_samples = unp_size / (avctx->channels * (bits + 1));

     if ((ret = ff_get_buffer(avctx, &s->frame)) < 0) {

         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
         return ret;
     }
     samples  = (int16_t *)s->frame.data[0];
     samples8 =            s->frame.data[0];
 

     // Initialize
     for(i = 0; i < (1 << (bits + stereo)); i++) {
         h[i].length = 256;
         h[i].maxlength = 0;
         h[i].current = 0;
         h[i].bits = av_mallocz(256 * 4);
         h[i].lengths = av_mallocz(256 * sizeof(int));
         h[i].values = av_mallocz(256 * sizeof(int));

         skip_bits1(&gb);

         if (smacker_decode_tree(&gb, &h[i], 0, 0) < 0) {
             for (; i >= 0; i--) {
                 if (vlc[i].table)
                     ff_free_vlc(&vlc[i]);
                 av_free(h[i].bits);
                 av_free(h[i].lengths);
                 av_free(h[i].values);
             }
             return AVERROR_INVALIDDATA;
         }

         skip_bits1(&gb);

         if(h[i].current > 1) {
             res = init_vlc(&vlc[i], SMKTREE_BITS, h[i].length,

                     h[i].lengths, sizeof(int), sizeof(int),
                     h[i].bits, sizeof(uint32_t), sizeof(uint32_t), INIT_VLC_LE);

             if(res < 0) {
                 av_log(avctx, AV_LOG_ERROR, "Cannot build VLC table\n");

                 return AVERROR_INVALIDDATA;

             }

         }
     }
     if(bits) { //decode 16-bit data

         for(i = stereo; i >= 0; i--)

             pred[i] = sign_extend(av_bswap16(get_bits(&gb, 16)), 16);

         for(i = 0; i <= stereo; i++)

             *samples++ = pred[i];

         for(; i < unp_size / 2; i++) {

             if(get_bits_left(&gb)<0)

                 return AVERROR_INVALIDDATA;

             if(i & stereo) {

                 if(vlc[2].table)
                     res = get_vlc2(&gb, vlc[2].table, SMKTREE_BITS, 3);
                 else
                     res = 0;

                 if (res < 0) {
                     av_log(avctx, AV_LOG_ERROR, "invalid vlc\n");
                     return AVERROR_INVALIDDATA;
                 }

                 val  = h[2].values[res];
                 if(vlc[3].table)
                     res = get_vlc2(&gb, vlc[3].table, SMKTREE_BITS, 3);
                 else
                     res = 0;

                 if (res < 0) {
                     av_log(avctx, AV_LOG_ERROR, "invalid vlc\n");
                     return AVERROR_INVALIDDATA;
                 }

                 val |= h[3].values[res] << 8;

                 pred[1] += sign_extend(val, 16);

                 *samples++ = pred[1];

             } else {

                 if(vlc[0].table)
                     res = get_vlc2(&gb, vlc[0].table, SMKTREE_BITS, 3);
                 else
                     res = 0;

                 if (res < 0) {
                     av_log(avctx, AV_LOG_ERROR, "invalid vlc\n");
                     return AVERROR_INVALIDDATA;
                 }

                 val  = h[0].values[res];
                 if(vlc[1].table)
                     res = get_vlc2(&gb, vlc[1].table, SMKTREE_BITS, 3);
                 else
                     res = 0;

                 if (res < 0) {
                     av_log(avctx, AV_LOG_ERROR, "invalid vlc\n");
                     return AVERROR_INVALIDDATA;
                 }

                 val |= h[1].values[res] << 8;

                 pred[0] += sign_extend(val, 16);

                 *samples++ = pred[0];

             }
         }
     } else { //8-bit data

         for(i = stereo; i >= 0; i--)
             pred[i] = get_bits(&gb, 8);

         for(i = 0; i <= stereo; i++)

             *samples8++ = pred[i];

         for(; i < unp_size; i++) {

             if(get_bits_left(&gb)<0)

                 return AVERROR_INVALIDDATA;

             if(i & stereo){

                 if(vlc[1].table)
                     res = get_vlc2(&gb, vlc[1].table, SMKTREE_BITS, 3);
                 else
                     res = 0;

                 if (res < 0) {
                     av_log(avctx, AV_LOG_ERROR, "invalid vlc\n");
                     return AVERROR_INVALIDDATA;
                 }

                 pred[1] += sign_extend(h[1].values[res], 8);

                 *samples8++ = av_clip_uint8(pred[1]);

             } else {

                 if(vlc[0].table)
                     res = get_vlc2(&gb, vlc[0].table, SMKTREE_BITS, 3);
                 else
                     res = 0;

                 if (res < 0) {
                     av_log(avctx, AV_LOG_ERROR, "invalid vlc\n");
                     return AVERROR_INVALIDDATA;
                 }

                 pred[0] += sign_extend(h[0].values[res], 8);

                 *samples8++ = av_clip_uint8(pred[0]);

             }
         }
     }
 
     for(i = 0; i < 4; i++) {
         if(vlc[i].table)

             ff_free_vlc(&vlc[i]);

         av_free(h[i].bits);
         av_free(h[i].lengths);
         av_free(h[i].values);

     }
 

     *got_frame_ptr   = 1;
     *(AVFrame *)data = s->frame;
 

     return buf_size;
 }
 

 AVCodec ff_smacker_decoder = {

     .name           = "smackvid",
     .type           = AVMEDIA_TYPE_VIDEO,

     .id             = AV_CODEC_ID_SMACKVIDEO,

     .priv_data_size = sizeof(SmackVContext),
     .init           = decode_init,
     .close          = decode_end,
     .decode         = decode_frame,
     .capabilities   = CODEC_CAP_DR1,

     .long_name      = NULL_IF_CONFIG_SMALL("Smacker video"),

 };
 

 AVCodec ff_smackaud_decoder = {

     .name           = "smackaud",
     .type           = AVMEDIA_TYPE_AUDIO,

     .id             = AV_CODEC_ID_SMACKAUDIO,

     .priv_data_size = sizeof(SmackerAudioContext),

     .init           = smka_decode_init,
     .decode         = smka_decode_frame,

     .capabilities   = CODEC_CAP_DR1,

     .long_name      = NULL_IF_CONFIG_SMALL("Smacker audio"),

 };