text: /*
   * 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/avassert.h"
  #include "libavutil/crc.h"
  #include "libavutil/intmath.h"
  #include "libavutil/md5.h"
  #include "libavutil/opt.h"
  #include "avcodec.h"
  #include "dsputil.h"
  #include "put_bits.h"
  #include "golomb.h"
  #include "internal.h"
  #include "lpc.h"
  #include "flac.h"
  #include "flacdata.h"
  #include "flacdsp.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
  
  enum CodingMode {
      CODING_MODE_RICE  = 4,
      CODING_MODE_RICE2 = 5,
  };
  
  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;
      int ch_mode;
  } CompressionOptions;
  
  typedef struct RiceContext {
      enum CodingMode coding_mode;
      int porder;
      int params[MAX_PARTITIONS];
  } RiceContext;
  
  typedef struct FlacSubframe {
      int type;
      int type_code;
      int obits;
      int wasted;
      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 bps_code;
      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;
      uint8_t *md5_buffer;
      unsigned int md5_buffer_size;
      DSPContext dsp;
      FLACDSPContext flac_dsp;
  } 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, s->avctx->bits_per_raw_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;
  
      av_assert0(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;
  
      switch (avctx->sample_fmt) {
      case AV_SAMPLE_FMT_S16:
          avctx->bits_per_raw_sample = 16;
          s->bps_code                = 4;
          break;
      case AV_SAMPLE_FMT_S32:
          if (avctx->bits_per_raw_sample != 24)
              av_log(avctx, AV_LOG_WARNING, "encoding as 24 bits-per-sample\n");
          avctx->bits_per_raw_sample = 24;
          s->bps_code                = 6;
          break;
      }
  
      if (channels < 1 || channels > FLAC_MAX_CHANNELS) {
          av_log(avctx, AV_LOG_ERROR, "%d channels not supported (max %d)\n",
                 channels, FLAC_MAX_CHANNELS);
          return AVERROR(EINVAL);
      }
      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 {
              av_log(avctx, AV_LOG_ERROR, "%d Hz not supported\n", freq);
              return AVERROR(EINVAL);
          }
          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 AVERROR(EINVAL);
      }
  
      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];
  
      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 AVERROR(EINVAL);
              }
          } 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 AVERROR(EINVAL);
          }
          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 AVERROR(EINVAL);
              }
          } 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 AVERROR(EINVAL);
          }
          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 AVERROR(EINVAL);
      }
  
      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 AVERROR(EINVAL);
          }
      } else {
          s->avctx->frame_size = select_blocksize(s->samplerate, s->options.block_time_ms);
      }
      s->max_blocksize = s->avctx->frame_size;
  
      /* set maximum encoded frame size in verbatim mode */
      s->max_framesize = ff_flac_get_max_frame_size(s->avctx->frame_size,
                                                    s->channels,
                                                    s->avctx->bits_per_raw_sample);
  
      /* initialize MD5 context */
      s->md5ctx = av_md5_alloc();
      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;
  
  #if FF_API_OLD_ENCODE_AUDIO
      avctx->coded_frame = avcodec_alloc_frame();
      if (!avctx->coded_frame)
          return AVERROR(ENOMEM);
  #endif
  
      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);
  
      ff_dsputil_init(&s->dsp, avctx);
      ff_flacdsp_init(&s->flac_dsp, avctx->sample_fmt,
                      avctx->bits_per_raw_sample);
  
      dprint_compression_options(s);
  
      return ret;
  }
  
  
  static void init_frame(FlacEncodeContext *s, int nb_samples)
  {
      int i, ch;
      FlacFrame *frame;
  
      frame = &s->frame;
  
      for (i = 0; i < 16; i++) {
          if (nb_samples == 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 = nb_samples;
          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++) {
          FlacSubframe *sub = &frame->subframes[ch];
  
          sub->wasted = 0;
          sub->obits  = s->avctx->bits_per_raw_sample;
  
          if (sub->obits > 16)
              sub->rc.coding_mode = CODING_MODE_RICE2;
          else
              sub->rc.coding_mode = CODING_MODE_RICE;
      }
  
      frame->verbatim_only = 0;
  }
  
  
  /**
   * Copy channel-interleaved input samples into separate subframes.
   */
  static void copy_samples(FlacEncodeContext *s, const void *samples)
  {
      int i, j, ch;
      FlacFrame *frame;
      int shift = av_get_bytes_per_sample(s->avctx->sample_fmt) * 8 -
                  s->avctx->bits_per_raw_sample;
  
  #define COPY_SAMPLES(bits) do {                                     \
      const int ## bits ## _t *samples0 = samples;                    \
      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] = samples0[j] >> shift; \
  } while (0)
  
      if (s->avctx->sample_fmt == AV_SAMPLE_FMT_S16)
          COPY_SAMPLES(16);
      else
          COPY_SAMPLES(32);
  }
  
  
  static uint64_t rice_count_exact(int32_t *res, int n, int k)
  {
      int i;
      uint64_t 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 uint64_t subframe_count_exact(FlacEncodeContext *s, FlacSubframe *sub,
                                       int pred_order)
  {
      int p, porder, psize;
      int i, part_end;
      uint64_t 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 += sub->rc.coding_mode;
              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(uint64_t sum, int n, int max_param)
  {
      int k;
      uint64_t sum2;
  
      if (sum <= n >> 1)
          return 0;
      sum2 = sum - (n >> 1);
      k    = av_log2(av_clipl_int32(sum2 / n));
      return FFMIN(k, max_param);
  }
  
  
  static uint64_t calc_optimal_rice_params(RiceContext *rc, int porder,
                                           uint64_t *sums, int n, int pred_order)
  {
      int i;
      int k, cnt, part, max_param;
      uint64_t all_bits;
  
      max_param = (1 << rc->coding_mode) - 2;
  
      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, max_param);
          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,
                        uint64_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++) {
          uint64_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 uint64_t calc_rice_params(RiceContext *rc, int pmin, int pmax,
                                   int32_t *data, int n, int pred_order)
  {
      int i;
      uint64_t bits[MAX_PARTITION_ORDER+1];
      int opt_porder;
      RiceContext tmp_rc;
      uint32_t *udata;
      uint64_t sums[MAX_PARTITION_ORDER+1][MAX_PARTITIONS];
  
      av_assert1(pmin >= 0 && pmin <= MAX_PARTITION_ORDER);
      av_assert1(pmax >= 0 && pmax <= MAX_PARTITION_ORDER);
      av_assert1(pmin <= pmax);
  
      tmp_rc.coding_mode = rc->coding_mode;
  
      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 uint64_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);
  
      uint64_t bits = 8 + pred_order * sub->obits + 2 + sub->rc.coding_mode;
      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;
          }
      }
  }
  
  
  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) {
          uint64_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;
          uint64_t bits[1 << ORDER_METHOD_8LEVEL];
          int order       = -1;
          int opt_index   = levels-1;
          opt_order       = max_order-1;
          bits[opt_index] = UINT32_MAX;
          for (i = levels-1; i >= 0; i--) {
              int last_order = order;
              order = min_order + (((max_order-min_order+1) * (i+1)) / levels)-1;
              order = av_clip(order, min_order - 1, max_order - 1);
              if (order == last_order)
                  continue;
              s->flac_dsp.lpc_encode(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
          uint64_t bits[MAX_LPC_ORDER];
          opt_order = 0;
          bits[0]   = UINT32_MAX;
          for (i = min_order-1; i < max_order; i++) {
              s->flac_dsp.lpc_encode(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) {
          uint64_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;
                  s->flac_dsp.lpc_encode(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];
  
      s->flac_dsp.lpc_encode(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;
      uint64_t 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
  
      count >>= 3;
      if (count > INT_MAX)
          return AVERROR_BUG;
      return count;
  }
  
  
  static void remove_wasted_bits(FlacEncodeContext *s)
  {
      int ch, i;
  
      for (ch = 0; ch < s->channels; ch++) {
          FlacSubframe *sub = &s->frame.subframes[ch];
          int32_t v         = 0;
  
          for (i = 0; i < s->frame.blocksize; i++) {
              v |= sub->samples[i];
              if (v & 1)
                  break;
          }
  
          if (v && !(v & 1)) {
              v = av_ctz(v);
  
              for (i = 0; i < s->frame.blocksize; i++)
                  sub->samples[i] >>= v;
  
              sub->wasted = v;
              sub->obits -= v;
  
              /* for 24-bit, check if removing wasted bits makes the range better
                 suited for using RICE instead of RICE2 for entropy coding */
              if (sub->obits <= 17)
                  sub->rc.coding_mode = CODING_MODE_RICE;
          }
      }
  }
  
  
  static int estimate_stereo_mode(int32_t *left_ch, int32_t *right_ch, int n,
                                  int max_rice_param)
  {
      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, max_rice_param);
          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;
  
      return best;
  }
  
  
  /**
   * 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;
      }
  
      if (s->options.ch_mode < 0) {
          int max_rice_param = (1 << frame->subframes[0].rc.coding_mode) - 2;
          frame->ch_mode = estimate_stereo_mode(left, right, n, max_rice_param);
      } else
          frame->ch_mode = s->options.ch_mode;
  
      /* 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 + FLAC_MAX_CHANNELS - 1);
  
      put_bits(&s->pb, 3, s->bps_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, !!sub->wasted);
          if (sub->wasted)
              put_bits(&s->pb, sub->wasted, 1);
  
          /* 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, sub->rc.coding_mode - 4);
  
              /* 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, sub->rc.coding_mode, 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, AVPacket *avpkt)
  {
      init_put_bits(&s->pb, avpkt->data, avpkt->size);
      write_frame_header(s);
      write_subframes(s);
      write_frame_footer(s);
      return put_bits_count(&s->pb) >> 3;
  }
  
  
  static int update_md5_sum(FlacEncodeContext *s, const void *samples)
  {
      const uint8_t *buf;
      int buf_size = s->frame.blocksize * s->channels *
                     ((s->avctx->bits_per_raw_sample + 7) / 8);
  
      if (s->avctx->bits_per_raw_sample > 16 || HAVE_BIGENDIAN) {
          av_fast_malloc(&s->md5_buffer, &s->md5_buffer_size, buf_size);
          if (!s->md5_buffer)
              return AVERROR(ENOMEM);
      }
  
      if (s->avctx->bits_per_raw_sample <= 16) {
          buf = (const uint8_t *)samples;
  #if HAVE_BIGENDIAN
          s->dsp.bswap16_buf((uint16_t *)s->md5_buffer,
                             (const uint16_t *)samples, buf_size / 2);
          buf = s->md5_buffer;
  #endif
      } else {
          int i;
          const int32_t *samples0 = samples;
          uint8_t *tmp            = s->md5_buffer;
  
          for (i = 0; i < s->frame.blocksize * s->channels; i++) {
              int32_t v = samples0[i] >> 8;
              *tmp++    = (v      ) & 0xFF;
              *tmp++    = (v >>  8) & 0xFF;
              *tmp++    = (v >> 16) & 0xFF;
          }
          buf = s->md5_buffer;
      }
      av_md5_update(s->md5ctx, buf, buf_size);
  
      return 0;
  }
  
  
  static int flac_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
                               const AVFrame *frame, int *got_packet_ptr)
  {
      FlacEncodeContext *s;
      int frame_bytes, out_bytes, ret;
  
      s = avctx->priv_data;
  
      /* when the last block is reached, update the header in extradata */
      if (!frame) {
          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 (frame->nb_samples < s->frame.blocksize) {
          s->max_framesize = ff_flac_get_max_frame_size(frame->nb_samples,
                                                        s->channels,
                                                        avctx->bits_per_raw_sample);
      }
  
      init_frame(s, frame->nb_samples);
  
      copy_samples(s, frame->data[0]);
  
      channel_decorrelation(s);
  
      remove_wasted_bits(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 < 0 || frame_bytes > s->max_framesize) {
          s->frame.verbatim_only = 1;
          frame_bytes = encode_frame(s);
          if (frame_bytes < 0) {
              av_log(avctx, AV_LOG_ERROR, "Bad frame count\n");
              return frame_bytes;
          }
      }
  
      if ((ret = ff_alloc_packet2(avctx, avpkt, frame_bytes)) < 0)
          return ret;
  
      out_bytes = write_frame(s, avpkt);
  
      s->frame_count++;
      s->sample_count += frame->nb_samples;
      if ((ret = update_md5_sum(s, frame->data[0])) < 0) {
          av_log(avctx, AV_LOG_ERROR, "Error updating MD5 checksum\n");
          return ret;
      }
      if (out_bytes > s->max_encoded_framesize)
          s->max_encoded_framesize = out_bytes;
      if (out_bytes < s->min_framesize)
          s->min_framesize = out_bytes;
  
      avpkt->pts      = frame->pts;
      avpkt->duration = ff_samples_to_time_base(avctx, frame->nb_samples);
      avpkt->size     = out_bytes;
      *got_packet_ptr = 1;
      return 0;
  }
  
  
  static av_cold int flac_encode_close(AVCodecContext *avctx)
  {
      if (avctx->priv_data) {
          FlacEncodeContext *s = avctx->priv_data;
          av_freep(&s->md5ctx);
          av_freep(&s->md5_buffer);
          ff_lpc_end(&s->lpc_ctx);
      }
      av_freep(&avctx->extradata);
      avctx->extradata_size = 0;
  #if FF_API_OLD_ENCODE_AUDIO
      av_freep(&avctx->coded_frame);
  #endif
      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), AV_OPT_TYPE_INT, {.i64 = 15 }, 0, MAX_LPC_PRECISION, FLAGS },
  { "lpc_type", "LPC algorithm", offsetof(FlacEncodeContext, options.lpc_type), AV_OPT_TYPE_INT, {.i64 = FF_LPC_TYPE_DEFAULT }, FF_LPC_TYPE_DEFAULT, FF_LPC_TYPE_NB-1, FLAGS, "lpc_type" },
  { "none",     NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_LPC_TYPE_NONE },     INT_MIN, INT_MAX, FLAGS, "lpc_type" },
  { "fixed",    NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_LPC_TYPE_FIXED },    INT_MIN, INT_MAX, FLAGS, "lpc_type" },
  { "levinson", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_LPC_TYPE_LEVINSON }, INT_MIN, INT_MAX, FLAGS, "lpc_type" },
  { "cholesky", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = 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),  AV_OPT_TYPE_INT, {.i64 = 2 }, 1, INT_MAX, FLAGS },
  { "min_partition_order",  NULL, offsetof(FlacEncodeContext, options.min_partition_order),  AV_OPT_TYPE_INT, {.i64 = -1 },      -1, MAX_PARTITION_ORDER, FLAGS },
  { "max_partition_order",  NULL, offsetof(FlacEncodeContext, options.max_partition_order),  AV_OPT_TYPE_INT, {.i64 = -1 },      -1, MAX_PARTITION_ORDER, FLAGS },
  { "prediction_order_method", "Search method for selecting prediction order", offsetof(FlacEncodeContext, options.prediction_order_method), AV_OPT_TYPE_INT, {.i64 = -1 }, -1, ORDER_METHOD_LOG, FLAGS, "predm" },
  { "estimation", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_EST },    INT_MIN, INT_MAX, FLAGS, "predm" },
  { "2level",     NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_2LEVEL }, INT_MIN, INT_MAX, FLAGS, "predm" },
  { "4level",     NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_4LEVEL }, INT_MIN, INT_MAX, FLAGS, "predm" },
  { "8level",     NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_8LEVEL }, INT_MIN, INT_MAX, FLAGS, "predm" },
  { "search",     NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_SEARCH }, INT_MIN, INT_MAX, FLAGS, "predm" },
  { "log",        NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_LOG },    INT_MIN, INT_MAX, FLAGS, "predm" },
  { "ch_mode", "Stereo decorrelation mode", offsetof(FlacEncodeContext, options.ch_mode), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, FLAC_CHMODE_MID_SIDE, FLAGS, "ch_mode" },
  { "auto",       NULL, 0, AV_OPT_TYPE_CONST, { .i64 = -1                      }, INT_MIN, INT_MAX, FLAGS, "ch_mode" },
  { "indep",      NULL, 0, AV_OPT_TYPE_CONST, { .i64 = FLAC_CHMODE_INDEPENDENT }, INT_MIN, INT_MAX, FLAGS, "ch_mode" },
  { "left_side",  NULL, 0, AV_OPT_TYPE_CONST, { .i64 = FLAC_CHMODE_LEFT_SIDE   }, INT_MIN, INT_MAX, FLAGS, "ch_mode" },
  { "right_side", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = FLAC_CHMODE_RIGHT_SIDE  }, INT_MIN, INT_MAX, FLAGS, "ch_mode" },
  { "mid_side",   NULL, 0, AV_OPT_TYPE_CONST, { .i64 = FLAC_CHMODE_MID_SIDE    }, INT_MIN, INT_MAX, FLAGS, "ch_mode" },
  { NULL },
  };
  
  static const AVClass flac_encoder_class = {
      "FLAC encoder",
      av_default_item_name,
      options,
      LIBAVUTIL_VERSION_INT,
  };
  
  AVCodec ff_flac_encoder = {
      .name           = "flac",
      .type           = AVMEDIA_TYPE_AUDIO,
      .id             = AV_CODEC_ID_FLAC,
      .priv_data_size = sizeof(FlacEncodeContext),
      .init           = flac_encode_init,
      .encode2        = flac_encode_frame,
      .close          = flac_encode_close,
      .capabilities   = CODEC_CAP_SMALL_LAST_FRAME | CODEC_CAP_DELAY | CODEC_CAP_LOSSLESS,
      .sample_fmts    = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
                                                       AV_SAMPLE_FMT_S32,
                                                       AV_SAMPLE_FMT_NONE },
      .long_name      = NULL_IF_CONFIG_SMALL("FLAC (Free Lossless Audio Codec)"),
      .priv_class     = &flac_encoder_class,
  };
  