/**
  * FLAC audio encoder

  * Copyright (c) 2006  Justin Ruggles <justin.ruggles@gmail.com>

  *

  * 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
  */
 

 #include "libavutil/crc.h"

 #include "libavutil/md5.h"

 #include "libavutil/opt.h"

 #include "avcodec.h"

 #include "get_bits.h"

 #include "golomb.h"

 #include "lpc.h"

 #include "flac.h"

 #include "flacdata.h"

 
 #define FLAC_SUBFRAME_CONSTANT  0
 #define FLAC_SUBFRAME_VERBATIM  1
 #define FLAC_SUBFRAME_FIXED     8
 #define FLAC_SUBFRAME_LPC      32
 

 #define MAX_FIXED_ORDER     4
 #define MAX_PARTITION_ORDER 8
 #define MAX_PARTITIONS     (1 << MAX_PARTITION_ORDER)
 #define MAX_LPC_PRECISION  15
 #define MAX_LPC_SHIFT      15
 #define MAX_RICE_PARAM     14
 
 typedef struct CompressionOptions {
     int compression_level;
     int block_time_ms;

     enum FFLPCType lpc_type;

     int lpc_passes;

     int lpc_coeff_precision;
     int min_prediction_order;
     int max_prediction_order;
     int prediction_order_method;
     int min_partition_order;
     int max_partition_order;
 } CompressionOptions;
 

 typedef struct RiceContext {
     int porder;

     int params[MAX_PARTITIONS];

 } RiceContext;
 

 typedef struct FlacSubframe {
     int type;
     int type_code;
     int obits;
     int order;

     int32_t coefs[MAX_LPC_ORDER];
     int shift;

     RiceContext rc;

     int32_t samples[FLAC_MAX_BLOCKSIZE];

     int32_t residual[FLAC_MAX_BLOCKSIZE+1];

 } FlacSubframe;
 
 typedef struct FlacFrame {

     FlacSubframe subframes[FLAC_MAX_CHANNELS];

     int blocksize;
     int bs_code[2];
     uint8_t crc8;
     int ch_mode;

     int verbatim_only;

 } FlacFrame;
 
 typedef struct FlacEncodeContext {

     AVClass *class;

     PutBitContext pb;

     int channels;
     int samplerate;

     int sr_code[2];

     int max_blocksize;

     int min_framesize;

     int max_framesize;

     int max_encoded_framesize;

     uint32_t frame_count;

     uint64_t sample_count;

     uint8_t md5sum[16];

     FlacFrame frame;

     CompressionOptions options;

     AVCodecContext *avctx;

     LPCContext lpc_ctx;

     struct AVMD5 *md5ctx;

 } FlacEncodeContext;
 

 /**

  * Write streaminfo metadata block to byte array.

  */
 static void write_streaminfo(FlacEncodeContext *s, uint8_t *header)
 {
     PutBitContext pb;
 
     memset(header, 0, FLAC_STREAMINFO_SIZE);
     init_put_bits(&pb, header, FLAC_STREAMINFO_SIZE);
 
     /* streaminfo metadata block */

     put_bits(&pb, 16, s->max_blocksize);
     put_bits(&pb, 16, s->max_blocksize);

     put_bits(&pb, 24, s->min_framesize);

     put_bits(&pb, 24, s->max_framesize);
     put_bits(&pb, 20, s->samplerate);
     put_bits(&pb, 3, s->channels-1);
     put_bits(&pb, 5, 15);       /* bits per sample - 1 */

     /* write 36-bit sample count in 2 put_bits() calls */
     put_bits(&pb, 24, (s->sample_count & 0xFFFFFF000LL) >> 12);
     put_bits(&pb, 12,  s->sample_count & 0x000000FFFLL);

     flush_put_bits(&pb);

     memcpy(&header[18], s->md5sum, 16);

 }
 

 /**

  * Set blocksize based on samplerate.
  * Choose the closest predefined blocksize >= BLOCK_TIME_MS milliseconds.

  */

 static int select_blocksize(int samplerate, int block_time_ms)

 {
     int i;
     int target;
     int blocksize;
 
     assert(samplerate > 0);

     blocksize = ff_flac_blocksize_table[1];

     target    = (samplerate * block_time_ms) / 1000;
     for (i = 0; i < 16; i++) {
         if (target >= ff_flac_blocksize_table[i] &&
             ff_flac_blocksize_table[i] > blocksize) {

             blocksize = ff_flac_blocksize_table[i];

         }
     }
     return blocksize;
 }
 

 static av_cold void dprint_compression_options(FlacEncodeContext *s)
 {
     AVCodecContext     *avctx = s->avctx;
     CompressionOptions *opt   = &s->options;
 
     av_log(avctx, AV_LOG_DEBUG, " compression: %d\n", opt->compression_level);
 
     switch (opt->lpc_type) {

     case FF_LPC_TYPE_NONE:

         av_log(avctx, AV_LOG_DEBUG, " lpc type: None\n");
         break;

     case FF_LPC_TYPE_FIXED:

         av_log(avctx, AV_LOG_DEBUG, " lpc type: Fixed pre-defined coefficients\n");
         break;

     case FF_LPC_TYPE_LEVINSON:

         av_log(avctx, AV_LOG_DEBUG, " lpc type: Levinson-Durbin recursion with Welch window\n");
         break;

     case FF_LPC_TYPE_CHOLESKY:

         av_log(avctx, AV_LOG_DEBUG, " lpc type: Cholesky factorization, %d pass%s\n",
                opt->lpc_passes, opt->lpc_passes == 1 ? "" : "es");
         break;
     }
 
     av_log(avctx, AV_LOG_DEBUG, " prediction order: %d, %d\n",
            opt->min_prediction_order, opt->max_prediction_order);
 
     switch (opt->prediction_order_method) {
     case ORDER_METHOD_EST:
         av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "estimate");
         break;
     case ORDER_METHOD_2LEVEL:
         av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "2-level");
         break;
     case ORDER_METHOD_4LEVEL:
         av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "4-level");
         break;
     case ORDER_METHOD_8LEVEL:
         av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "8-level");
         break;
     case ORDER_METHOD_SEARCH:
         av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "full search");
         break;
     case ORDER_METHOD_LOG:
         av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "log search");
         break;
     }
 
 
     av_log(avctx, AV_LOG_DEBUG, " partition order: %d, %d\n",
            opt->min_partition_order, opt->max_partition_order);
 
     av_log(avctx, AV_LOG_DEBUG, " block size: %d\n", avctx->frame_size);
 
     av_log(avctx, AV_LOG_DEBUG, " lpc precision: %d\n",
            opt->lpc_coeff_precision);
 }
 
 

 static av_cold int flac_encode_init(AVCodecContext *avctx)

 {
     int freq = avctx->sample_rate;
     int channels = avctx->channels;
     FlacEncodeContext *s = avctx->priv_data;

     int i, level, ret;

     uint8_t *streaminfo;
 

     s->avctx = avctx;
 

     if (avctx->sample_fmt != AV_SAMPLE_FMT_S16)

         return -1;
 

     if (channels < 1 || channels > FLAC_MAX_CHANNELS)

         return -1;
     s->channels = channels;
 
     /* find samplerate in table */

     if (freq < 1)

         return -1;

     for (i = 4; i < 12; i++) {
         if (freq == ff_flac_sample_rate_table[i]) {

             s->samplerate = ff_flac_sample_rate_table[i];

             s->sr_code[0] = i;
             s->sr_code[1] = 0;
             break;
         }
     }
     /* if not in table, samplerate is non-standard */

     if (i == 12) {
         if (freq % 1000 == 0 && freq < 255000) {

             s->sr_code[0] = 12;
             s->sr_code[1] = freq / 1000;

         } else if (freq % 10 == 0 && freq < 655350) {

             s->sr_code[0] = 14;
             s->sr_code[1] = freq / 10;

         } else if (freq < 65535) {

             s->sr_code[0] = 13;
             s->sr_code[1] = freq;
         } else {
             return -1;
         }
         s->samplerate = freq;
     }
 

     /* set compression option defaults based on avctx->compression_level */

     if (avctx->compression_level < 0)

         s->options.compression_level = 5;

     else

         s->options.compression_level = avctx->compression_level;
 

     level = s->options.compression_level;
     if (level > 12) {

         av_log(avctx, AV_LOG_ERROR, "invalid compression level: %d\n",
                s->options.compression_level);
         return -1;
     }
 

     s->options.block_time_ms = ((int[]){ 27, 27, 27,105,105,105,105,105,105,105,105,105,105})[level];
 

     if (s->options.lpc_type == FF_LPC_TYPE_DEFAULT)
         s->options.lpc_type  = ((int[]){ FF_LPC_TYPE_FIXED,    FF_LPC_TYPE_FIXED,    FF_LPC_TYPE_FIXED,
                                          FF_LPC_TYPE_LEVINSON, FF_LPC_TYPE_LEVINSON, FF_LPC_TYPE_LEVINSON,
                                          FF_LPC_TYPE_LEVINSON, FF_LPC_TYPE_LEVINSON, FF_LPC_TYPE_LEVINSON,
                                          FF_LPC_TYPE_LEVINSON, FF_LPC_TYPE_LEVINSON, FF_LPC_TYPE_LEVINSON,
                                          FF_LPC_TYPE_LEVINSON})[level];

 
     s->options.min_prediction_order = ((int[]){  2,  0,  0,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1})[level];
     s->options.max_prediction_order = ((int[]){  3,  4,  4,  6,  8,  8,  8,  8, 12, 12, 12, 32, 32})[level];
 

     if (s->options.prediction_order_method < 0)
         s->options.prediction_order_method = ((int[]){ ORDER_METHOD_EST,    ORDER_METHOD_EST,    ORDER_METHOD_EST,
                                                        ORDER_METHOD_EST,    ORDER_METHOD_EST,    ORDER_METHOD_EST,
                                                        ORDER_METHOD_4LEVEL, ORDER_METHOD_LOG,    ORDER_METHOD_4LEVEL,
                                                        ORDER_METHOD_LOG,    ORDER_METHOD_SEARCH, ORDER_METHOD_LOG,
                                                        ORDER_METHOD_SEARCH})[level];

     if (s->options.min_partition_order > s->options.max_partition_order) {
         av_log(avctx, AV_LOG_ERROR, "invalid partition orders: min=%d max=%d\n",
                s->options.min_partition_order, s->options.max_partition_order);
         return AVERROR(EINVAL);
     }
     if (s->options.min_partition_order < 0)
         s->options.min_partition_order = ((int[]){  2,  2,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0})[level];
     if (s->options.max_partition_order < 0)
         s->options.max_partition_order = ((int[]){  2,  2,  3,  3,  3,  8,  8,  8,  8,  8,  8,  8,  8})[level];

     /* set compression option overrides from AVCodecContext */

 #if FF_API_FLAC_GLOBAL_OPTS
     if (avctx->lpc_type > FF_LPC_TYPE_DEFAULT) {
         if (avctx->lpc_type > FF_LPC_TYPE_CHOLESKY) {

             av_log(avctx, AV_LOG_ERROR, "unknown lpc type: %d\n", avctx->lpc_type);
             return -1;
         }
         s->options.lpc_type = avctx->lpc_type;

         if (s->options.lpc_type == FF_LPC_TYPE_CHOLESKY) {

             if (avctx->lpc_passes < 0) {
                 // default number of passes for Cholesky
                 s->options.lpc_passes = 2;
             } else if (avctx->lpc_passes == 0) {
                 av_log(avctx, AV_LOG_ERROR, "invalid number of lpc passes: %d\n",
                        avctx->lpc_passes);

                 return -1;

             } else {
                 s->options.lpc_passes = avctx->lpc_passes;

             }

         }
     }

 #endif

     if (s->options.lpc_type == FF_LPC_TYPE_NONE) {

         s->options.min_prediction_order = 0;
     } else if (avctx->min_prediction_order >= 0) {

         if (s->options.lpc_type == FF_LPC_TYPE_FIXED) {

             if (avctx->min_prediction_order > MAX_FIXED_ORDER) {

                 av_log(avctx, AV_LOG_ERROR, "invalid min prediction order: %d\n",
                        avctx->min_prediction_order);
                 return -1;
             }

         } else if (avctx->min_prediction_order < MIN_LPC_ORDER ||
                    avctx->min_prediction_order > MAX_LPC_ORDER) {

             av_log(avctx, AV_LOG_ERROR, "invalid min prediction order: %d\n",
                    avctx->min_prediction_order);
             return -1;

         }
         s->options.min_prediction_order = avctx->min_prediction_order;
     }

     if (s->options.lpc_type == FF_LPC_TYPE_NONE) {

         s->options.max_prediction_order = 0;
     } else if (avctx->max_prediction_order >= 0) {

         if (s->options.lpc_type == FF_LPC_TYPE_FIXED) {

             if (avctx->max_prediction_order > MAX_FIXED_ORDER) {

                 av_log(avctx, AV_LOG_ERROR, "invalid max prediction order: %d\n",
                        avctx->max_prediction_order);
                 return -1;
             }

         } else if (avctx->max_prediction_order < MIN_LPC_ORDER ||
                    avctx->max_prediction_order > MAX_LPC_ORDER) {
             av_log(avctx, AV_LOG_ERROR, "invalid max prediction order: %d\n",
                    avctx->max_prediction_order);
             return -1;

         }
         s->options.max_prediction_order = avctx->max_prediction_order;
     }

     if (s->options.max_prediction_order < s->options.min_prediction_order) {

         av_log(avctx, AV_LOG_ERROR, "invalid prediction orders: min=%d max=%d\n",
                s->options.min_prediction_order, s->options.max_prediction_order);
         return -1;
     }
 

 #if FF_API_FLAC_GLOBAL_OPTS

     if (avctx->prediction_order_method >= 0) {
         if (avctx->prediction_order_method > ORDER_METHOD_LOG) {

             av_log(avctx, AV_LOG_ERROR, "invalid prediction order method: %d\n",
                    avctx->prediction_order_method);
             return -1;
         }
         s->options.prediction_order_method = avctx->prediction_order_method;
     }
 

     if (avctx->min_partition_order >= 0) {
         if (avctx->min_partition_order > MAX_PARTITION_ORDER) {

             av_log(avctx, AV_LOG_ERROR, "invalid min partition order: %d\n",
                    avctx->min_partition_order);
             return -1;
         }
         s->options.min_partition_order = avctx->min_partition_order;
     }

     if (avctx->max_partition_order >= 0) {
         if (avctx->max_partition_order > MAX_PARTITION_ORDER) {

             av_log(avctx, AV_LOG_ERROR, "invalid max partition order: %d\n",
                    avctx->max_partition_order);
             return -1;
         }
         s->options.max_partition_order = avctx->max_partition_order;
     }

     if (s->options.max_partition_order < s->options.min_partition_order) {

         av_log(avctx, AV_LOG_ERROR, "invalid partition orders: min=%d max=%d\n",
                s->options.min_partition_order, s->options.max_partition_order);
         return -1;
     }

 #endif

     if (avctx->frame_size > 0) {
         if (avctx->frame_size < FLAC_MIN_BLOCKSIZE ||

                 avctx->frame_size > FLAC_MAX_BLOCKSIZE) {

             av_log(avctx, AV_LOG_ERROR, "invalid block size: %d\n",
                    avctx->frame_size);
             return -1;
         }
     } else {

         s->avctx->frame_size = select_blocksize(s->samplerate, s->options.block_time_ms);

     }

     s->max_blocksize = s->avctx->frame_size;

 #if FF_API_FLAC_GLOBAL_OPTS

     /* set LPC precision */

     if (avctx->lpc_coeff_precision > 0) {
         if (avctx->lpc_coeff_precision > MAX_LPC_PRECISION) {

             av_log(avctx, AV_LOG_ERROR, "invalid lpc coeff precision: %d\n",
                    avctx->lpc_coeff_precision);
             return -1;
         }
         s->options.lpc_coeff_precision = avctx->lpc_coeff_precision;
     }

 #endif

     /* set maximum encoded frame size in verbatim mode */

     s->max_framesize = ff_flac_get_max_frame_size(s->avctx->frame_size,
                                                   s->channels, 16);

     /* initialize MD5 context */
     s->md5ctx = av_malloc(av_md5_size);

     if (!s->md5ctx)

         return AVERROR(ENOMEM);

     av_md5_init(s->md5ctx);
 

     streaminfo = av_malloc(FLAC_STREAMINFO_SIZE);

     if (!streaminfo)
         return AVERROR(ENOMEM);

     write_streaminfo(s, streaminfo);
     avctx->extradata = streaminfo;
     avctx->extradata_size = FLAC_STREAMINFO_SIZE;
 

     s->frame_count   = 0;

     s->min_framesize = s->max_framesize;

 
     avctx->coded_frame = avcodec_alloc_frame();

     if (!avctx->coded_frame)
         return AVERROR(ENOMEM);

     if (channels == 3 &&
             avctx->channel_layout != (AV_CH_LAYOUT_STEREO|AV_CH_FRONT_CENTER) ||
         channels == 4 &&
             avctx->channel_layout != AV_CH_LAYOUT_2_2 &&
             avctx->channel_layout != AV_CH_LAYOUT_QUAD ||
         channels == 5 &&
             avctx->channel_layout != AV_CH_LAYOUT_5POINT0 &&
             avctx->channel_layout != AV_CH_LAYOUT_5POINT0_BACK ||
         channels == 6 &&
             avctx->channel_layout != AV_CH_LAYOUT_5POINT1 &&
             avctx->channel_layout != AV_CH_LAYOUT_5POINT1_BACK) {
         if (avctx->channel_layout) {
             av_log(avctx, AV_LOG_ERROR, "Channel layout not supported by Flac, "
                                              "output stream will have incorrect "
                                              "channel layout.\n");
         } else {
             av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The encoder "
                                                "will use Flac channel layout for "
                                                "%d channels.\n", channels);
         }
     }
 

     ret = ff_lpc_init(&s->lpc_ctx, avctx->frame_size,

                       s->options.max_prediction_order, FF_LPC_TYPE_LEVINSON);

     dprint_compression_options(s);
 

     return ret;

 }
 

 static void init_frame(FlacEncodeContext *s)

 {
     int i, ch;
     FlacFrame *frame;
 
     frame = &s->frame;
 

     for (i = 0; i < 16; i++) {
         if (s->avctx->frame_size == ff_flac_blocksize_table[i]) {
             frame->blocksize  = ff_flac_blocksize_table[i];

             frame->bs_code[0] = i;
             frame->bs_code[1] = 0;
             break;
         }
     }

     if (i == 16) {

         frame->blocksize = s->avctx->frame_size;

         if (frame->blocksize <= 256) {

             frame->bs_code[0] = 6;
             frame->bs_code[1] = frame->blocksize-1;
         } else {
             frame->bs_code[0] = 7;
             frame->bs_code[1] = frame->blocksize-1;
         }
     }
 

     for (ch = 0; ch < s->channels; ch++)

         frame->subframes[ch].obits = 16;

 
     frame->verbatim_only = 0;

 }
 

 /**

  * Copy channel-interleaved input samples into separate subframes.

  */

 static void copy_samples(FlacEncodeContext *s, const int16_t *samples)

 {
     int i, j, ch;
     FlacFrame *frame;
 
     frame = &s->frame;

     for (i = 0, j = 0; i < frame->blocksize; i++)
         for (ch = 0; ch < s->channels; ch++, j++)

             frame->subframes[ch].samples[i] = samples[j];
 }
 

 static int rice_count_exact(int32_t *res, int n, int k)
 {
     int i;
     int count = 0;
 
     for (i = 0; i < n; i++) {
         int32_t v = -2 * res[i] - 1;
         v ^= v >> 31;
         count += (v >> k) + 1 + k;
     }
     return count;
 }
 
 
 static int subframe_count_exact(FlacEncodeContext *s, FlacSubframe *sub,
                                 int pred_order)
 {
     int p, porder, psize;
     int i, part_end;
     int count = 0;
 
     /* subframe header */
     count += 8;
 
     /* subframe */
     if (sub->type == FLAC_SUBFRAME_CONSTANT) {
         count += sub->obits;
     } else if (sub->type == FLAC_SUBFRAME_VERBATIM) {
         count += s->frame.blocksize * sub->obits;
     } else {
         /* warm-up samples */
         count += pred_order * sub->obits;
 
         /* LPC coefficients */
         if (sub->type == FLAC_SUBFRAME_LPC)
             count += 4 + 5 + pred_order * s->options.lpc_coeff_precision;
 
         /* rice-encoded block */
         count += 2;
 
         /* partition order */
         porder = sub->rc.porder;
         psize  = s->frame.blocksize >> porder;
         count += 4;
 
         /* residual */
         i        = pred_order;
         part_end = psize;
         for (p = 0; p < 1 << porder; p++) {
             int k = sub->rc.params[p];
             count += 4;
             count += rice_count_exact(&sub->residual[i], part_end - i, k);
             i = part_end;
             part_end = FFMIN(s->frame.blocksize, part_end + psize);
         }
     }
 
     return count;
 }
 
 

 #define rice_encode_count(sum, n, k) (((n)*((k)+1))+((sum-(n>>1))>>(k)))
 

 /**

  * Solve for d/dk(rice_encode_count) = n-((sum-(n>>1))>>(k+1)) = 0.

  */

 static int find_optimal_param(uint32_t sum, int n)
 {

     int k;
     uint32_t sum2;
 

     if (sum <= n >> 1)

         return 0;

     sum2 = sum - (n >> 1);
     k    = av_log2(n < 256 ? FASTDIV(sum2, n) : sum2 / n);

     return FFMIN(k, MAX_RICE_PARAM);

 }
 

 static uint32_t calc_optimal_rice_params(RiceContext *rc, int porder,
                                          uint32_t *sums, int n, int pred_order)
 {
     int i;
     int k, cnt, part;
     uint32_t all_bits;
 

     part     = (1 << porder);

     all_bits = 4 * part;

 
     cnt = (n >> porder) - pred_order;

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

         k = find_optimal_param(sums[i], cnt);
         rc->params[i] = k;
         all_bits += rice_encode_count(sums[i], cnt, k);

         cnt = n >> porder;

     }
 
     rc->porder = porder;
 
     return all_bits;
 }
 

 static void calc_sums(int pmin, int pmax, uint32_t *data, int n, int pred_order,
                       uint32_t sums[][MAX_PARTITIONS])

 {
     int i, j;

     int parts;
     uint32_t *res, *res_end;

 
     /* sums for highest level */

     parts   = (1 << pmax);
     res     = &data[pred_order];

     res_end = &data[n >> pmax];

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

         uint32_t sum = 0;

         while (res < res_end)

             sum += *(res++);
         sums[pmax][i] = sum;

         res_end += n >> pmax;

     }
     /* sums for lower levels */

     for (i = pmax - 1; i >= pmin; i--) {

         parts = (1 << i);

         for (j = 0; j < parts; j++)

             sums[i][j] = sums[i+1][2*j] + sums[i+1][2*j+1];
     }
 }
 

 static uint32_t calc_rice_params(RiceContext *rc, int pmin, int pmax,
                                  int32_t *data, int n, int pred_order)

 {
     int i;

     uint32_t bits[MAX_PARTITION_ORDER+1];

     int opt_porder;

     RiceContext tmp_rc;

     uint32_t *udata;

     uint32_t sums[MAX_PARTITION_ORDER+1][MAX_PARTITIONS];

     assert(pmin >= 0 && pmin <= MAX_PARTITION_ORDER);
     assert(pmax >= 0 && pmax <= MAX_PARTITION_ORDER);
     assert(pmin <= pmax);

 
     udata = av_malloc(n * sizeof(uint32_t));

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

         udata[i] = (2*data[i]) ^ (data[i]>>31);
 

     calc_sums(pmin, pmax, udata, n, pred_order, sums);

     opt_porder = pmin;
     bits[pmin] = UINT32_MAX;

     for (i = pmin; i <= pmax; i++) {

         bits[i] = calc_optimal_rice_params(&tmp_rc, i, sums[i], n, pred_order);

         if (bits[i] <= bits[opt_porder]) {

             opt_porder = i;

             *rc = tmp_rc;

         }
     }
 
     av_freep(&udata);

     return bits[opt_porder];

 }
 

 static int get_max_p_order(int max_porder, int n, int order)
 {
     int porder = FFMIN(max_porder, av_log2(n^(n-1)));

     if (order > 0)

         porder = FFMIN(porder, av_log2(n/order));
     return porder;
 }
 

 static uint32_t find_subframe_rice_params(FlacEncodeContext *s,

                                           FlacSubframe *sub, int pred_order)

 {

     int pmin = get_max_p_order(s->options.min_partition_order,
                                s->frame.blocksize, pred_order);
     int pmax = get_max_p_order(s->options.max_partition_order,
                                s->frame.blocksize, pred_order);
 
     uint32_t bits = 8 + pred_order * sub->obits + 2 + 4;
     if (sub->type == FLAC_SUBFRAME_LPC)
         bits += 4 + 5 + pred_order * s->options.lpc_coeff_precision;
     bits += calc_rice_params(&sub->rc, pmin, pmax, sub->residual,
                              s->frame.blocksize, pred_order);

     return bits;
 }
 

 static void encode_residual_fixed(int32_t *res, const int32_t *smp, int n,
                                   int order)

 {
     int i;
 

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

         res[i] = smp[i];
 

     if (order == 0) {
         for (i = order; i < n; i++)
             res[i] = smp[i];
     } else if (order == 1) {
         for (i = order; i < n; i++)
             res[i] = smp[i] - smp[i-1];
     } else if (order == 2) {

         int a = smp[order-1] - smp[order-2];

         for (i = order; i < n; i += 2) {
             int b    = smp[i  ] - smp[i-1];
             res[i]   = b - a;
             a        = smp[i+1] - smp[i  ];
             res[i+1] = a - b;

         }

     } else if (order == 3) {
         int a = smp[order-1] -   smp[order-2];

         int c = smp[order-1] - 2*smp[order-2] + smp[order-3];

         for (i = order; i < n; i += 2) {
             int b    = smp[i  ] - smp[i-1];
             int d    = b - a;
             res[i]   = d - c;
             a        = smp[i+1] - smp[i  ];
             c        = a - b;
             res[i+1] = c - d;

         }

     } else {
         int a = smp[order-1] -   smp[order-2];
         int c = smp[order-1] - 2*smp[order-2] +   smp[order-3];

         int e = smp[order-1] - 3*smp[order-2] + 3*smp[order-3] - smp[order-4];

         for (i = order; i < n; i += 2) {
             int b    = smp[i  ] - smp[i-1];
             int d    = b - a;
             int f    = d - c;
             res[i  ] = f - e;
             a        = smp[i+1] - smp[i  ];
             c        = a - b;
             e        = c - d;
             res[i+1] = e - f;

         }

     }
 }
 

 #define LPC1(x) {\

     int c = coefs[(x)-1];\

     p0   += c * s;\
     s     = smp[i-(x)+1];\
     p1   += c * s;\

 }
 

 static av_always_inline void encode_residual_lpc_unrolled(int32_t *res,
                                     const int32_t *smp, int n, int order,
                                     const int32_t *coefs, int shift, int big)

 {
     int i;

     for (i = order; i < n; i += 2) {
         int s  = smp[i-order];

         int p0 = 0, p1 = 0;

         if (big) {
             switch (order) {
             case 32: LPC1(32)
             case 31: LPC1(31)
             case 30: LPC1(30)
             case 29: LPC1(29)
             case 28: LPC1(28)
             case 27: LPC1(27)
             case 26: LPC1(26)
             case 25: LPC1(25)
             case 24: LPC1(24)
             case 23: LPC1(23)
             case 22: LPC1(22)
             case 21: LPC1(21)
             case 20: LPC1(20)
             case 19: LPC1(19)
             case 18: LPC1(18)
             case 17: LPC1(17)
             case 16: LPC1(16)
             case 15: LPC1(15)
             case 14: LPC1(14)
             case 13: LPC1(13)
             case 12: LPC1(12)
             case 11: LPC1(11)
             case 10: LPC1(10)
             case  9: LPC1( 9)
                      LPC1( 8)
                      LPC1( 7)
                      LPC1( 6)
                      LPC1( 5)
                      LPC1( 4)
                      LPC1( 3)
                      LPC1( 2)
                      LPC1( 1)

             }
         } else {

             switch (order) {
             case  8: LPC1( 8)
             case  7: LPC1( 7)
             case  6: LPC1( 6)
             case  5: LPC1( 5)
             case  4: LPC1( 4)
             case  3: LPC1( 3)
             case  2: LPC1( 2)
             case  1: LPC1( 1)

             }
         }
         res[i  ] = smp[i  ] - (p0 >> shift);
         res[i+1] = smp[i+1] - (p1 >> shift);
     }
 }
 

 static void encode_residual_lpc(int32_t *res, const int32_t *smp, int n,
                                 int order, const int32_t *coefs, int shift)
 {

     int i;

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

         res[i] = smp[i];

 #if CONFIG_SMALL

     for (i = order; i < n; i += 2) {

         int j;

         int s  = smp[i];

         int p0 = 0, p1 = 0;

         for (j = 0; j < order; j++) {

             int c = coefs[j];

             p1   += c * s;
             s     = smp[i-j-1];
             p0   += c * s;

         }

         res[i  ] = smp[i  ] - (p0 >> shift);

         res[i+1] = smp[i+1] - (p1 >> shift);

     }

 #else

     switch (order) {
     case  1: encode_residual_lpc_unrolled(res, smp, n, 1, coefs, shift, 0); break;
     case  2: encode_residual_lpc_unrolled(res, smp, n, 2, coefs, shift, 0); break;
     case  3: encode_residual_lpc_unrolled(res, smp, n, 3, coefs, shift, 0); break;
     case  4: encode_residual_lpc_unrolled(res, smp, n, 4, coefs, shift, 0); break;
     case  5: encode_residual_lpc_unrolled(res, smp, n, 5, coefs, shift, 0); break;
     case  6: encode_residual_lpc_unrolled(res, smp, n, 6, coefs, shift, 0); break;
     case  7: encode_residual_lpc_unrolled(res, smp, n, 7, coefs, shift, 0); break;
     case  8: encode_residual_lpc_unrolled(res, smp, n, 8, coefs, shift, 0); break;
     default: encode_residual_lpc_unrolled(res, smp, n, order, coefs, shift, 1); break;

     }
 #endif

 }
 

 static int encode_residual_ch(FlacEncodeContext *s, int ch)

 {

     int i, n;

     int min_order, max_order, opt_order, omethod;

     FlacFrame *frame;
     FlacSubframe *sub;

     int32_t coefs[MAX_LPC_ORDER][MAX_LPC_ORDER];
     int shift[MAX_LPC_ORDER];

     int32_t *res, *smp;
 

     frame = &s->frame;

     sub   = &frame->subframes[ch];
     res   = sub->residual;
     smp   = sub->samples;
     n     = frame->blocksize;

 
     /* CONSTANT */

     for (i = 1; i < n; i++)
         if(smp[i] != smp[0])
             break;
     if (i == n) {

         sub->type = sub->type_code = FLAC_SUBFRAME_CONSTANT;
         res[0] = smp[0];

         return subframe_count_exact(s, sub, 0);

     }
 
     /* VERBATIM */

     if (frame->verbatim_only || n < 5) {

         sub->type = sub->type_code = FLAC_SUBFRAME_VERBATIM;

         memcpy(res, smp, n * sizeof(int32_t));

         return subframe_count_exact(s, sub, 0);

     }
 

     min_order  = s->options.min_prediction_order;
     max_order  = s->options.max_prediction_order;
     omethod    = s->options.prediction_order_method;

 
     /* FIXED */

     sub->type = FLAC_SUBFRAME_FIXED;

     if (s->options.lpc_type == FF_LPC_TYPE_NONE  ||
         s->options.lpc_type == FF_LPC_TYPE_FIXED || n <= max_order) {

         uint32_t bits[MAX_FIXED_ORDER+1];

         if (max_order > MAX_FIXED_ORDER)
             max_order = MAX_FIXED_ORDER;

         opt_order = 0;

         bits[0]   = UINT32_MAX;
         for (i = min_order; i <= max_order; i++) {

             encode_residual_fixed(res, smp, n, i);

             bits[i] = find_subframe_rice_params(s, sub, i);

             if (bits[i] < bits[opt_order])

                 opt_order = i;

         }

         sub->order     = opt_order;

         sub->type_code = sub->type | sub->order;

         if (sub->order != max_order) {

             encode_residual_fixed(res, smp, n, sub->order);

             find_subframe_rice_params(s, sub, sub->order);

         }

         return subframe_count_exact(s, sub, sub->order);

     }

 
     /* LPC */

     sub->type = FLAC_SUBFRAME_LPC;

     opt_order = ff_lpc_calc_coefs(&s->lpc_ctx, smp, n, min_order, max_order,

                                   s->options.lpc_coeff_precision, coefs, shift, s->options.lpc_type,

                                   s->options.lpc_passes, omethod,

                                   MAX_LPC_SHIFT, 0);

     if (omethod == ORDER_METHOD_2LEVEL ||
         omethod == ORDER_METHOD_4LEVEL ||
         omethod == ORDER_METHOD_8LEVEL) {

         int levels = 1 << omethod;

         uint32_t bits[1 << ORDER_METHOD_8LEVEL];

         int order;

         int opt_index   = levels-1;
         opt_order       = max_order-1;

         bits[opt_index] = UINT32_MAX;

         for (i = levels-1; i >= 0; i--) {

             order = min_order + (((max_order-min_order+1) * (i+1)) / levels)-1;

             if (order < 0)
                 order = 0;

             encode_residual_lpc(res, smp, n, order+1, coefs[order], shift[order]);

             bits[i] = find_subframe_rice_params(s, sub, order+1);

             if (bits[i] < bits[opt_index]) {

                 opt_index = i;
                 opt_order = order;
             }
         }
         opt_order++;

     } else if (omethod == ORDER_METHOD_SEARCH) {

         // brute-force optimal order search
         uint32_t bits[MAX_LPC_ORDER];
         opt_order = 0;

         bits[0]   = UINT32_MAX;
         for (i = min_order-1; i < max_order; i++) {

             encode_residual_lpc(res, smp, n, i+1, coefs[i], shift[i]);

             bits[i] = find_subframe_rice_params(s, sub, i+1);

             if (bits[i] < bits[opt_order])

                 opt_order = i;
         }
         opt_order++;

     } else if (omethod == ORDER_METHOD_LOG) {

         uint32_t bits[MAX_LPC_ORDER];
         int step;
 

         opt_order = min_order - 1 + (max_order-min_order)/3;

         memset(bits, -1, sizeof(bits));
 

         for (step = 16; step; step >>= 1) {
             int last = opt_order;
             for (i = last-step; i <= last+step; i += step) {
                 if (i < min_order-1 || i >= max_order || bits[i] < UINT32_MAX)

                     continue;
                 encode_residual_lpc(res, smp, n, i+1, coefs[i], shift[i]);

                 bits[i] = find_subframe_rice_params(s, sub, i+1);

                 if (bits[i] < bits[opt_order])
                     opt_order = i;

             }
         }
         opt_order++;

     }
 

     sub->order     = opt_order;

     sub->type_code = sub->type | (sub->order-1);

     sub->shift     = shift[sub->order-1];
     for (i = 0; i < sub->order; i++)

         sub->coefs[i] = coefs[sub->order-1][i];

     encode_residual_lpc(res, smp, n, sub->order, sub->coefs, sub->shift);

     find_subframe_rice_params(s, sub, sub->order);
 
     return subframe_count_exact(s, sub, sub->order);

 }
 

 static int count_frame_header(FlacEncodeContext *s)
 {

     uint8_t av_unused tmp;

     int count;
 
     /*
     <14> Sync code
     <1>  Reserved
     <1>  Blocking strategy
     <4>  Block size in inter-channel samples
     <4>  Sample rate
     <4>  Channel assignment
     <3>  Sample size in bits
     <1>  Reserved
     */
     count = 32;
 
     /* coded frame number */
     PUT_UTF8(s->frame_count, tmp, count += 8;)
 
     /* explicit block size */

     if (s->frame.bs_code[0] == 6)
         count += 8;
     else if (s->frame.bs_code[0] == 7)
         count += 16;

 
     /* explicit sample rate */
     count += ((s->sr_code[0] == 12) + (s->sr_code[0] > 12)) * 8;
 
     /* frame header CRC-8 */
     count += 8;
 
     return count;
 }
 
 
 static int encode_frame(FlacEncodeContext *s)
 {
     int ch, count;
 
     count = count_frame_header(s);
 
     for (ch = 0; ch < s->channels; ch++)
         count += encode_residual_ch(s, ch);
 
     count += (8 - (count & 7)) & 7; // byte alignment
     count += 16;                    // CRC-16
 
     return count >> 3;
 }
 
 

 static int estimate_stereo_mode(int32_t *left_ch, int32_t *right_ch, int n)
 {
     int i, best;
     int32_t lt, rt;

     uint64_t sum[4];

     uint64_t score[4];

     int k;

     /* calculate sum of 2nd order residual for each channel */

     sum[0] = sum[1] = sum[2] = sum[3] = 0;

     for (i = 2; i < n; i++) {
         lt = left_ch[i]  - 2*left_ch[i-1]  + left_ch[i-2];

         rt = right_ch[i] - 2*right_ch[i-1] + right_ch[i-2];

         sum[2] += FFABS((lt + rt) >> 1);
         sum[3] += FFABS(lt - rt);
         sum[0] += FFABS(lt);
         sum[1] += FFABS(rt);

     }

     /* estimate bit counts */

     for (i = 0; i < 4; i++) {
         k      = find_optimal_param(2 * sum[i], n);
         sum[i] = rice_encode_count( 2 * sum[i], n, k);

     }
 
     /* calculate score for each mode */

     score[0] = sum[0] + sum[1];
     score[1] = sum[0] + sum[3];
     score[2] = sum[1] + sum[3];
     score[3] = sum[2] + sum[3];

 
     /* return mode with lowest score */
     best = 0;

     for (i = 1; i < 4; i++)
         if (score[i] < score[best])

             best = i;

     if (best == 0) {

         return FLAC_CHMODE_INDEPENDENT;

     } else if (best == 1) {

         return FLAC_CHMODE_LEFT_SIDE;

     } else if (best == 2) {

         return FLAC_CHMODE_RIGHT_SIDE;
     } else {
         return FLAC_CHMODE_MID_SIDE;
     }
 }
 

 /**

  * Perform stereo channel decorrelation.

  */

 static void channel_decorrelation(FlacEncodeContext *s)

 {
     FlacFrame *frame;
     int32_t *left, *right;
     int i, n;
 

     frame = &s->frame;

     n     = frame->blocksize;

     left  = frame->subframes[0].samples;
     right = frame->subframes[1].samples;
 

     if (s->channels != 2) {

         frame->ch_mode = FLAC_CHMODE_INDEPENDENT;

         return;
     }
 
     frame->ch_mode = estimate_stereo_mode(left, right, n);
 
     /* perform decorrelation and adjust bits-per-sample */

     if (frame->ch_mode == FLAC_CHMODE_INDEPENDENT)

         return;

     if (frame->ch_mode == FLAC_CHMODE_MID_SIDE) {

         int32_t tmp;

         for (i = 0; i < n; i++) {
             tmp      = left[i];
             left[i]  = (tmp + right[i]) >> 1;
             right[i] =  tmp - right[i];

         }
         frame->subframes[1].obits++;

     } else if (frame->ch_mode == FLAC_CHMODE_LEFT_SIDE) {
         for (i = 0; i < n; i++)

             right[i] = left[i] - right[i];
         frame->subframes[1].obits++;
     } else {

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

             left[i] -= right[i];
         frame->subframes[0].obits++;
     }
 }
 

 static void write_utf8(PutBitContext *pb, uint32_t val)

 {

     uint8_t tmp;
     PUT_UTF8(val, tmp, put_bits(pb, 8, tmp);)

 }
 

 static void write_frame_header(FlacEncodeContext *s)

 {
     FlacFrame *frame;
     int crc;
 
     frame = &s->frame;
 
     put_bits(&s->pb, 16, 0xFFF8);
     put_bits(&s->pb, 4, frame->bs_code[0]);
     put_bits(&s->pb, 4, s->sr_code[0]);

 
     if (frame->ch_mode == FLAC_CHMODE_INDEPENDENT)

         put_bits(&s->pb, 4, s->channels-1);

     else

         put_bits(&s->pb, 4, frame->ch_mode);

     put_bits(&s->pb, 3, 4); /* bits-per-sample code */
     put_bits(&s->pb, 1, 0);
     write_utf8(&s->pb, s->frame_count);

 
     if (frame->bs_code[0] == 6)

         put_bits(&s->pb, 8, frame->bs_code[1]);

     else if (frame->bs_code[0] == 7)

         put_bits(&s->pb, 16, frame->bs_code[1]);

 
     if (s->sr_code[0] == 12)

         put_bits(&s->pb, 8, s->sr_code[1]);

     else if (s->sr_code[0] > 12)

         put_bits(&s->pb, 16, s->sr_code[1]);

     flush_put_bits(&s->pb);

     crc = av_crc(av_crc_get_table(AV_CRC_8_ATM), 0, s->pb.buf,
                  put_bits_count(&s->pb) >> 3);

     put_bits(&s->pb, 8, crc);
 }
 

 static void write_subframes(FlacEncodeContext *s)

 {

     int ch;
 
     for (ch = 0; ch < s->channels; ch++) {
         FlacSubframe *sub = &s->frame.subframes[ch];

         int i, p, porder, psize;
         int32_t *part_end;
         int32_t *res       =  sub->residual;
         int32_t *frame_end = &sub->residual[s->frame.blocksize];

         /* subframe header */
         put_bits(&s->pb, 1, 0);
         put_bits(&s->pb, 6, sub->type_code);
         put_bits(&s->pb, 1, 0); /* no wasted bits */
 
         /* subframe */

         if (sub->type == FLAC_SUBFRAME_CONSTANT) {
             put_sbits(&s->pb, sub->obits, res[0]);
         } else if (sub->type == FLAC_SUBFRAME_VERBATIM) {
             while (res < frame_end)
                 put_sbits(&s->pb, sub->obits, *res++);
         } else {
             /* warm-up samples */

             for (i = 0; i < sub->order; i++)

                 put_sbits(&s->pb, sub->obits, *res++);
 
             /* LPC coefficients */
             if (sub->type == FLAC_SUBFRAME_LPC) {
                 int cbits = s->options.lpc_coeff_precision;
                 put_bits( &s->pb, 4, cbits-1);
                 put_sbits(&s->pb, 5, sub->shift);
                 for (i = 0; i < sub->order; i++)
                     put_sbits(&s->pb, cbits, sub->coefs[i]);
             }

             /* rice-encoded block */
             put_bits(&s->pb, 2, 0);
 
             /* partition order */
             porder  = sub->rc.porder;
             psize   = s->frame.blocksize >> porder;
             put_bits(&s->pb, 4, porder);
 
             /* residual */
             part_end  = &sub->residual[psize];
             for (p = 0; p < 1 << porder; p++) {
                 int k = sub->rc.params[p];
                 put_bits(&s->pb, 4, k);
                 while (res < part_end)
                     set_sr_golomb_flac(&s->pb, *res++, k, INT32_MAX, 0);
                 part_end = FFMIN(frame_end, part_end + psize);
             }

         }

     }

 }
 

 static void write_frame_footer(FlacEncodeContext *s)

 {
     int crc;
     flush_put_bits(&s->pb);

     crc = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, s->pb.buf,
                             put_bits_count(&s->pb)>>3));

     put_bits(&s->pb, 16, crc);
     flush_put_bits(&s->pb);
 }
 

 static int write_frame(FlacEncodeContext *s, uint8_t *frame, int buf_size)
 {
     init_put_bits(&s->pb, frame, buf_size);

     write_frame_header(s);
     write_subframes(s);
     write_frame_footer(s);

     return put_bits_count(&s->pb) >> 3;
 }
 
 

 static void update_md5_sum(FlacEncodeContext *s, const int16_t *samples)

 {

 #if HAVE_BIGENDIAN

     int i;

     for (i = 0; i < s->frame.blocksize * s->channels; i++) {

         int16_t smp = av_le2ne16(samples[i]);

         av_md5_update(s->md5ctx, (uint8_t *)&smp, 2);
     }
 #else

     av_md5_update(s->md5ctx, (const uint8_t *)samples, s->frame.blocksize*s->channels*2);

 #endif
 }
 

 static int flac_encode_frame(AVCodecContext *avctx, uint8_t *frame,
                              int buf_size, void *data)
 {
     FlacEncodeContext *s;

     const int16_t *samples = data;

     int frame_bytes, out_bytes;

 
     s = avctx->priv_data;
 

     /* when the last block is reached, update the header in extradata */
     if (!data) {

         s->max_framesize = s->max_encoded_framesize;

         av_md5_final(s->md5ctx, s->md5sum);

         write_streaminfo(s, avctx->extradata);
         return 0;
     }
 

     /* change max_framesize for small final frame */
     if (avctx->frame_size < s->frame.blocksize) {
         s->max_framesize = ff_flac_get_max_frame_size(avctx->frame_size,
                                                       s->channels, 16);
     }
 

     init_frame(s);

 
     copy_samples(s, samples);
 

     channel_decorrelation(s);
 

     frame_bytes = encode_frame(s);

     /* fallback to verbatim mode if the compressed frame is larger than it
        would be if encoded uncompressed. */

     if (frame_bytes > s->max_framesize) {

         s->frame.verbatim_only = 1;

         frame_bytes = encode_frame(s);

     }
 

     if (buf_size < frame_bytes) {
         av_log(avctx, AV_LOG_ERROR, "output buffer too small\n");
         return 0;
     }
     out_bytes = write_frame(s, frame, buf_size);
 

     s->frame_count++;

     avctx->coded_frame->pts = s->sample_count;

     s->sample_count += avctx->frame_size;

     update_md5_sum(s, samples);

     if (out_bytes > s->max_encoded_framesize)
         s->max_encoded_framesize = out_bytes;

     if (out_bytes < s->min_framesize)
         s->min_framesize = out_bytes;

     return out_bytes;
 }
 

 static av_cold int flac_encode_close(AVCodecContext *avctx)

 {

     if (avctx->priv_data) {
         FlacEncodeContext *s = avctx->priv_data;
         av_freep(&s->md5ctx);

         ff_lpc_end(&s->lpc_ctx);

     }

     av_freep(&avctx->extradata);
     avctx->extradata_size = 0;

     av_freep(&avctx->coded_frame);
     return 0;
 }
 

 #define FLAGS AV_OPT_FLAG_ENCODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM
 static const AVOption options[] = {

 { "lpc_coeff_precision", "LPC coefficient precision", offsetof(FlacEncodeContext, options.lpc_coeff_precision), FF_OPT_TYPE_INT, {.dbl = 15 }, 0, MAX_LPC_PRECISION, FLAGS },
 { "lpc_type", "LPC algorithm", offsetof(FlacEncodeContext, options.lpc_type), FF_OPT_TYPE_INT, {.dbl = FF_LPC_TYPE_DEFAULT }, FF_LPC_TYPE_DEFAULT, FF_LPC_TYPE_NB-1, FLAGS, "lpc_type" },
 { "none",     NULL, 0, FF_OPT_TYPE_CONST, {.dbl = FF_LPC_TYPE_NONE },     INT_MIN, INT_MAX, FLAGS, "lpc_type" },
 { "fixed",    NULL, 0, FF_OPT_TYPE_CONST, {.dbl = FF_LPC_TYPE_FIXED },    INT_MIN, INT_MAX, FLAGS, "lpc_type" },
 { "levinson", NULL, 0, FF_OPT_TYPE_CONST, {.dbl = FF_LPC_TYPE_LEVINSON }, INT_MIN, INT_MAX, FLAGS, "lpc_type" },
 { "cholesky", NULL, 0, FF_OPT_TYPE_CONST, {.dbl = FF_LPC_TYPE_CHOLESKY }, INT_MIN, INT_MAX, FLAGS, "lpc_type" },
 { "lpc_passes", "Number of passes to use for Cholesky factorization during LPC analysis", offsetof(FlacEncodeContext, options.lpc_passes),  FF_OPT_TYPE_INT, {.dbl = -1 }, INT_MIN, INT_MAX, FLAGS },
 { "min_partition_order",  NULL, offsetof(FlacEncodeContext, options.min_partition_order),  FF_OPT_TYPE_INT, {.dbl = -1 },      -1, MAX_PARTITION_ORDER, FLAGS },
 { "max_partition_order",  NULL, offsetof(FlacEncodeContext, options.max_partition_order),  FF_OPT_TYPE_INT, {.dbl = -1 },      -1, MAX_PARTITION_ORDER, FLAGS },
 { "prediction_order_method", "Search method for selecting prediction order", offsetof(FlacEncodeContext, options.prediction_order_method), FF_OPT_TYPE_INT, {.dbl = -1 }, -1, ORDER_METHOD_LOG, FLAGS, "predm" },
 { "estimation", NULL, 0, FF_OPT_TYPE_CONST, {.dbl = ORDER_METHOD_EST },    INT_MIN, INT_MAX, FLAGS, "predm" },
 { "2level",     NULL, 0, FF_OPT_TYPE_CONST, {.dbl = ORDER_METHOD_2LEVEL }, INT_MIN, INT_MAX, FLAGS, "predm" },
 { "4level",     NULL, 0, FF_OPT_TYPE_CONST, {.dbl = ORDER_METHOD_4LEVEL }, INT_MIN, INT_MAX, FLAGS, "predm" },
 { "8level",     NULL, 0, FF_OPT_TYPE_CONST, {.dbl = ORDER_METHOD_8LEVEL }, INT_MIN, INT_MAX, FLAGS, "predm" },
 { "search",     NULL, 0, FF_OPT_TYPE_CONST, {.dbl = ORDER_METHOD_SEARCH }, INT_MIN, INT_MAX, FLAGS, "predm" },
 { "log",        NULL, 0, FF_OPT_TYPE_CONST, {.dbl = ORDER_METHOD_LOG },    INT_MIN, INT_MAX, FLAGS, "predm" },

 { NULL },
 };
 
 static const AVClass flac_encoder_class = {
     "FLAC encoder",
     av_default_item_name,
     options,
     LIBAVUTIL_VERSION_INT,
 };

 AVCodec ff_flac_encoder = {

     "flac",

     AVMEDIA_TYPE_AUDIO,

     CODEC_ID_FLAC,
     sizeof(FlacEncodeContext),
     flac_encode_init,
     flac_encode_frame,
     flac_encode_close,
     NULL,

     .capabilities = CODEC_CAP_SMALL_LAST_FRAME | CODEC_CAP_DELAY | CODEC_CAP_LOSSLESS,

     .sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE},

     .long_name = NULL_IF_CONFIG_SMALL("FLAC (Free Lossless Audio Codec)"),

     .priv_class = &flac_encoder_class,

 };