/*

  * Windows Media Audio Lossless decoder

  * Copyright (c) 2007 Baptiste Coudurier, Benjamin Larsson, Ulion
  * Copyright (c) 2008 - 2011 Sascha Sommer, Benjamin Larsson
  * Copyright (c) 2011 Andreas Öman

  * Copyright (c) 2011 - 2012 Mashiat Sarker Shakkhar

  *
  * 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 <inttypes.h>
 

 #include "libavutil/attributes.h"

 #include "libavutil/avassert.h"
 

 #include "avcodec.h"
 #include "internal.h"
 #include "get_bits.h"
 #include "put_bits.h"

 #include "lossless_audiodsp.h"

 #include "wma.h"

 #include "wma_common.h"

 
 /** current decoder limitations */

 #define WMALL_MAX_CHANNELS      8                       ///< max number of handled channels
 #define MAX_SUBFRAMES          32                       ///< max number of subframes per channel
 #define MAX_BANDS              29                       ///< max number of scale factor bands
 #define MAX_FRAMESIZE       32768                       ///< maximum compressed frame size

 #define MAX_ORDER             256

 
 #define WMALL_BLOCK_MIN_BITS    6                       ///< log2 of min block size

 #define WMALL_BLOCK_MAX_BITS   14                       ///< log2 of max block size

 #define WMALL_BLOCK_MAX_SIZE (1 << WMALL_BLOCK_MAX_BITS)    ///< maximum block size

 #define WMALL_BLOCK_SIZES    (WMALL_BLOCK_MAX_BITS - WMALL_BLOCK_MIN_BITS + 1) ///< possible block sizes
 

 #define WMALL_COEFF_PAD_SIZE   16                       ///< pad coef buffers with 0 for use with SIMD

 
 /**

  * @brief frame-specific decoder context for a single channel

  */

 typedef struct WmallChannelCtx {

     int16_t     prev_block_len;                         ///< length of the previous block
     uint8_t     transmit_coefs;
     uint8_t     num_subframes;
     uint16_t    subframe_len[MAX_SUBFRAMES];            ///< subframe length in samples
     uint16_t    subframe_offsets[MAX_SUBFRAMES];        ///< subframe positions in the current frame
     uint8_t     cur_subframe;                           ///< current subframe number
     uint16_t    decoded_samples;                        ///< number of already processed samples
     int         quant_step;                             ///< quantization step for the current subframe
     int         transient_counter;                      ///< number of transient samples from the beginning of the transient zone

 } WmallChannelCtx;
 
 /**
  * @brief main decoder context
  */
 typedef struct WmallDecodeCtx {
     /* generic decoder variables */

     AVCodecContext  *avctx;

     AVFrame         *frame;

     LLAudDSPContext dsp;                           ///< accelerated DSP functions

     uint8_t         *frame_data;                    ///< compressed frame data
     int             max_frame_size;                 ///< max bitstream size

     PutBitContext   pb;                             ///< context for filling the frame_data buffer

 
     /* frame size dependent frame information (set during initialization) */

     uint32_t        decode_flags;                   ///< used compression features
     int             len_prefix;                     ///< frame is prefixed with its length
     int             dynamic_range_compression;      ///< frame contains DRC data
     uint8_t         bits_per_sample;                ///< integer audio sample size for the unscaled IMDCT output (used to scale to [-1.0, 1.0])
     uint16_t        samples_per_frame;              ///< number of samples to output
     uint16_t        log2_frame_size;
     int8_t          num_channels;                   ///< number of channels in the stream (same as AVCodecContext.num_channels)
     int8_t          lfe_channel;                    ///< lfe channel index
     uint8_t         max_num_subframes;
     uint8_t         subframe_len_bits;              ///< number of bits used for the subframe length
     uint8_t         max_subframe_len_bit;           ///< flag indicating that the subframe is of maximum size when the first subframe length bit is 1
     uint16_t        min_samples_per_subframe;

 
     /* packet decode state */

     GetBitContext   pgb;                            ///< bitstream reader context for the packet
     int             next_packet_start;              ///< start offset of the next WMA packet in the demuxer packet
     uint8_t         packet_offset;                  ///< offset to the frame in the packet
     uint8_t         packet_sequence_number;         ///< current packet number
     int             num_saved_bits;                 ///< saved number of bits
     int             frame_offset;                   ///< frame offset in the bit reservoir
     int             subframe_offset;                ///< subframe offset in the bit reservoir
     uint8_t         packet_loss;                    ///< set in case of bitstream error
     uint8_t         packet_done;                    ///< set when a packet is fully decoded

 
     /* frame decode state */

     uint32_t        frame_num;                      ///< current frame number (not used for decoding)
     GetBitContext   gb;                             ///< bitstream reader context
     int             buf_bit_size;                   ///< buffer size in bits

     int16_t         *samples_16[WMALL_MAX_CHANNELS]; ///< current sample buffer pointer (16-bit)
     int32_t         *samples_32[WMALL_MAX_CHANNELS]; ///< current sample buffer pointer (24-bit)

     uint8_t         drc_gain;                       ///< gain for the DRC tool
     int8_t          skip_frame;                     ///< skip output step
     int8_t          parsed_all_subframes;           ///< all subframes decoded?

 
     /* subframe/block decode state */

     int16_t         subframe_len;                   ///< current subframe length
     int8_t          channels_for_cur_subframe;      ///< number of channels that contain the subframe
     int8_t          channel_indexes_for_cur_subframe[WMALL_MAX_CHANNELS];

     WmallChannelCtx channel[WMALL_MAX_CHANNELS];    ///< per channel data

     // WMA Lossless-specific

 
     uint8_t do_arith_coding;
     uint8_t do_ac_filter;
     uint8_t do_inter_ch_decorr;
     uint8_t do_mclms;
     uint8_t do_lpc;
 

     int8_t  acfilter_order;
     int8_t  acfilter_scaling;

     int16_t acfilter_coeffs[16];

     int     acfilter_prevvalues[WMALL_MAX_CHANNELS][16];

     int8_t  mclms_order;
     int8_t  mclms_scaling;

     int16_t mclms_coeffs[WMALL_MAX_CHANNELS * WMALL_MAX_CHANNELS * 32];
     int16_t mclms_coeffs_cur[WMALL_MAX_CHANNELS * WMALL_MAX_CHANNELS];

     int32_t mclms_prevvalues[WMALL_MAX_CHANNELS * 2 * 32];
     int32_t mclms_updates[WMALL_MAX_CHANNELS * 2 * 32];

     int     mclms_recent;

     int     movave_scaling;
     int     quant_stepsize;

 
     struct {

         int order;
         int scaling;
         int coefsend;
         int bitsend;

         DECLARE_ALIGNED(16, int16_t, coefs)[MAX_ORDER + WMALL_COEFF_PAD_SIZE/sizeof(int16_t)];

         DECLARE_ALIGNED(16, int32_t, lms_prevvalues)[MAX_ORDER * 2 + WMALL_COEFF_PAD_SIZE/sizeof(int16_t)];

         DECLARE_ALIGNED(16, int16_t, lms_updates)[MAX_ORDER * 2 + WMALL_COEFF_PAD_SIZE/sizeof(int16_t)];

         int recent;

     } cdlms[WMALL_MAX_CHANNELS][9];

     int cdlms_ttl[WMALL_MAX_CHANNELS];

 
     int bV3RTM;
 

     int is_channel_coded[WMALL_MAX_CHANNELS];
     int update_speed[WMALL_MAX_CHANNELS];

     int transient[WMALL_MAX_CHANNELS];
     int transient_pos[WMALL_MAX_CHANNELS];

     int seekable_tile;
 

     int ave_sum[WMALL_MAX_CHANNELS];

     int channel_residues[WMALL_MAX_CHANNELS][WMALL_BLOCK_MAX_SIZE];

     int lpc_coefs[WMALL_MAX_CHANNELS][40];

     int lpc_order;
     int lpc_scaling;
     int lpc_intbits;
 } WmallDecodeCtx;
 

 /** Get sign of integer (1 for positive, -1 for negative and 0 for zero) */

 #define WMASIGN(x) (((x) > 0) - ((x) < 0))

 
 static av_cold int decode_init(AVCodecContext *avctx)
 {

     WmallDecodeCtx *s  = avctx->priv_data;

     uint8_t *edata_ptr = avctx->extradata;
     unsigned int channel_mask;

     int i, log2_max_num_subframes;

     if (!avctx->block_align) {
         av_log(avctx, AV_LOG_ERROR, "block_align is not set\n");
         return AVERROR(EINVAL);
     }
 

     s->max_frame_size = MAX_FRAMESIZE * avctx->channels;
     s->frame_data = av_mallocz(s->max_frame_size + AV_INPUT_BUFFER_PADDING_SIZE);
     if (!s->frame_data)
         return AVERROR(ENOMEM);
 

     s->avctx = avctx;

     ff_llauddsp_init(&s->dsp);

     init_put_bits(&s->pb, s->frame_data, s->max_frame_size);

 
     if (avctx->extradata_size >= 18) {

         s->decode_flags    = AV_RL16(edata_ptr + 14);
         channel_mask       = AV_RL32(edata_ptr +  2);

         s->bits_per_sample = AV_RL16(edata_ptr);

         if (s->bits_per_sample == 16)

             avctx->sample_fmt = AV_SAMPLE_FMT_S16P;

         else if (s->bits_per_sample == 24) {

             avctx->sample_fmt = AV_SAMPLE_FMT_S32P;

             avctx->bits_per_raw_sample = 24;

         } else {

             av_log(avctx, AV_LOG_ERROR, "Unknown bit-depth: %"PRIu8"\n",

                    s->bits_per_sample);
             return AVERROR_INVALIDDATA;
         }

         /* dump the extradata */

         for (i = 0; i < avctx->extradata_size; i++)

             ff_dlog(avctx, "[%x] ", avctx->extradata[i]);
         ff_dlog(avctx, "\n");

 
     } else {

         avpriv_request_sample(avctx, "Unsupported extradata size");

         return AVERROR_PATCHWELCOME;

     }
 

     /* generic init */

     s->log2_frame_size = av_log2(avctx->block_align) + 4;
 

     /* frame info */

     s->skip_frame  = 1; /* skip first frame */
     s->packet_loss = 1;

     s->len_prefix  = s->decode_flags & 0x40;

     /* get frame len */
     s->samples_per_frame = 1 << ff_wma_get_frame_len_bits(avctx->sample_rate,
                                                           3, s->decode_flags);

     av_assert0(s->samples_per_frame <= WMALL_BLOCK_MAX_SIZE);

     /* init previous block len */

     for (i = 0; i < avctx->channels; i++)
         s->channel[i].prev_block_len = s->samples_per_frame;
 

     /* subframe info */
     log2_max_num_subframes  = (s->decode_flags & 0x38) >> 3;

     s->max_num_subframes    = 1 << log2_max_num_subframes;

     s->max_subframe_len_bit = 0;

     s->subframe_len_bits    = av_log2(log2_max_num_subframes) + 1;

 
     s->min_samples_per_subframe  = s->samples_per_frame / s->max_num_subframes;

     s->dynamic_range_compression = s->decode_flags & 0x80;
     s->bV3RTM                    = s->decode_flags & 0x100;

 
     if (s->max_num_subframes > MAX_SUBFRAMES) {

         av_log(avctx, AV_LOG_ERROR, "invalid number of subframes %"PRIu8"\n",

                s->max_num_subframes);
         return AVERROR_INVALIDDATA;
     }
 
     s->num_channels = avctx->channels;
 

     /* extract lfe channel position */

     s->lfe_channel = -1;
 
     if (channel_mask & 8) {
         unsigned int mask;

         for (mask = 1; mask < 16; mask <<= 1)

             if (channel_mask & mask)
                 ++s->lfe_channel;
     }
 
     if (s->num_channels < 0) {

         av_log(avctx, AV_LOG_ERROR, "invalid number of channels %"PRId8"\n",

                s->num_channels);

         return AVERROR_INVALIDDATA;
     } else if (s->num_channels > WMALL_MAX_CHANNELS) {

         avpriv_request_sample(avctx,
                               "More than %d channels", WMALL_MAX_CHANNELS);

         return AVERROR_PATCHWELCOME;
     }
 

     s->frame = av_frame_alloc();
     if (!s->frame)
         return AVERROR(ENOMEM);
 

     avctx->channel_layout = channel_mask;
     return 0;
 }
 
 /**

  * @brief Decode the subframe length.
  * @param s      context
  * @param offset sample offset in the frame
  * @return decoded subframe length on success, < 0 in case of an error

  */
 static int decode_subframe_length(WmallDecodeCtx *s, int offset)
 {

     int frame_len_ratio, subframe_len, len;

     /* no need to read from the bitstream when only one length is possible */

     if (offset == s->samples_per_frame - s->min_samples_per_subframe)
         return s->min_samples_per_subframe;
 

     len             = av_log2(s->max_num_subframes - 1) + 1;

     frame_len_ratio = get_bits(&s->gb, len);

     subframe_len    = s->min_samples_per_subframe * (frame_len_ratio + 1);

     /* sanity check the length */

     if (subframe_len < s->min_samples_per_subframe ||
         subframe_len > s->samples_per_frame) {
         av_log(s->avctx, AV_LOG_ERROR, "broken frame: subframe_len %i\n",
                subframe_len);
         return AVERROR_INVALIDDATA;
     }
     return subframe_len;
 }
 
 /**

  * @brief Decode how the data in the frame is split into subframes.

  *       Every WMA frame contains the encoded data for a fixed number of
  *       samples per channel. The data for every channel might be split
  *       into several subframes. This function will reconstruct the list of
  *       subframes for every channel.
  *
  *       If the subframes are not evenly split, the algorithm estimates the
  *       channels with the lowest number of total samples.
  *       Afterwards, for each of these channels a bit is read from the
  *       bitstream that indicates if the channel contains a subframe with the
  *       next subframe size that is going to be read from the bitstream or not.
  *       If a channel contains such a subframe, the subframe size gets added to
  *       the channel's subframe list.
  *       The algorithm repeats these steps until the frame is properly divided
  *       between the individual channels.
  *

  * @param s context
  * @return 0 on success, < 0 in case of an error

  */

 static int decode_tilehdr(WmallDecodeCtx *s)

 {

     uint16_t num_samples[WMALL_MAX_CHANNELS] = { 0 }; /* sum of samples for all currently known subframes of a channel */
     uint8_t  contains_subframe[WMALL_MAX_CHANNELS];   /* flag indicating if a channel contains the current subframe */
     int channels_for_cur_subframe = s->num_channels;  /* number of channels that contain the current subframe */
     int fixed_channel_layout = 0;                     /* flag indicating that all channels use the same subfra2me offsets and sizes */
     int min_channel_len = 0;                          /* smallest sum of samples (channels with this length will be processed first) */
     int c, tile_aligned;
 
     /* reset tiling information */

     for (c = 0; c < s->num_channels; c++)
         s->channel[c].num_subframes = 0;
 

     tile_aligned = get_bits1(&s->gb);
     if (s->max_num_subframes == 1 || tile_aligned)

         fixed_channel_layout = 1;

     /* loop until the frame data is split between the subframes */

     do {

         int subframe_len, in_use = 0;

         /* check which channels contain the subframe */

         for (c = 0; c < s->num_channels; c++) {
             if (num_samples[c] == min_channel_len) {
                 if (fixed_channel_layout || channels_for_cur_subframe == 1 ||

                    (min_channel_len == s->samples_per_frame - s->min_samples_per_subframe)) {

                     contains_subframe[c] = 1;

                 } else {

                     contains_subframe[c] = get_bits1(&s->gb);

                 }

                 in_use |= contains_subframe[c];

             } else
                 contains_subframe[c] = 0;
         }
 

         if (!in_use) {
             av_log(s->avctx, AV_LOG_ERROR,
                    "Found empty subframe\n");
             return AVERROR_INVALIDDATA;
         }
 

         /* get subframe length, subframe_len == 0 is not allowed */

         if ((subframe_len = decode_subframe_length(s, min_channel_len)) <= 0)

             return AVERROR_INVALIDDATA;

         /* add subframes to the individual channels and find new min_channel_len */

         min_channel_len += subframe_len;
         for (c = 0; c < s->num_channels; c++) {

             WmallChannelCtx *chan = &s->channel[c];

 
             if (contains_subframe[c]) {
                 if (chan->num_subframes >= MAX_SUBFRAMES) {
                     av_log(s->avctx, AV_LOG_ERROR,
                            "broken frame: num subframes > 31\n");
                     return AVERROR_INVALIDDATA;
                 }
                 chan->subframe_len[chan->num_subframes] = subframe_len;
                 num_samples[c] += subframe_len;
                 ++chan->num_subframes;
                 if (num_samples[c] > s->samples_per_frame) {
                     av_log(s->avctx, AV_LOG_ERROR, "broken frame: "

                            "channel len(%"PRIu16") > samples_per_frame(%"PRIu16")\n",

                            num_samples[c], s->samples_per_frame);

                     return AVERROR_INVALIDDATA;
                 }
             } else if (num_samples[c] <= min_channel_len) {
                 if (num_samples[c] < min_channel_len) {
                     channels_for_cur_subframe = 0;
                     min_channel_len = num_samples[c];
                 }
                 ++channels_for_cur_subframe;
             }
         }
     } while (min_channel_len < s->samples_per_frame);
 
     for (c = 0; c < s->num_channels; c++) {

         int i, offset = 0;

         for (i = 0; i < s->channel[c].num_subframes; i++) {

             s->channel[c].subframe_offsets[i] = offset;

             offset += s->channel[c].subframe_len[i];
         }
     }
 
     return 0;
 }
 
 static void decode_ac_filter(WmallDecodeCtx *s)
 {
     int i;

     s->acfilter_order   = get_bits(&s->gb, 4) + 1;

     s->acfilter_scaling = get_bits(&s->gb, 4);
 

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

         s->acfilter_coeffs[i] = get_bitsz(&s->gb, s->acfilter_scaling) + 1;

 }
 
 static void decode_mclms(WmallDecodeCtx *s)
 {

     s->mclms_order   = (get_bits(&s->gb, 4) + 1) * 2;

     s->mclms_scaling = get_bits(&s->gb, 4);

     if (get_bits1(&s->gb)) {
         int i, send_coef_bits;

         int cbits = av_log2(s->mclms_scaling + 1);

         if (1 << cbits < s->mclms_scaling + 1)

             cbits++;
 

         send_coef_bits = get_bitsz(&s->gb, cbits) + 2;

         for (i = 0; i < s->mclms_order * s->num_channels * s->num_channels; i++)

             s->mclms_coeffs[i] = get_bits(&s->gb, send_coef_bits);
 

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

             int c;

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

                 s->mclms_coeffs_cur[i * s->num_channels + c] = get_bits(&s->gb, send_coef_bits);
         }

     }
 }
 

 static int decode_cdlms(WmallDecodeCtx *s)

 {
     int c, i;
     int cdlms_send_coef = get_bits1(&s->gb);
 

     for (c = 0; c < s->num_channels; c++) {

         s->cdlms_ttl[c] = get_bits(&s->gb, 3) + 1;

         for (i = 0; i < s->cdlms_ttl[c]; i++) {

             s->cdlms[c][i].order = (get_bits(&s->gb, 7) + 1) * 8;

             if (s->cdlms[c][i].order > MAX_ORDER) {
                 av_log(s->avctx, AV_LOG_ERROR,
                        "Order[%d][%d] %d > max (%d), not supported\n",
                        c, i, s->cdlms[c][i].order, MAX_ORDER);
                 s->cdlms[0][0].order = 0;
                 return AVERROR_INVALIDDATA;
             }

             if(s->cdlms[c][i].order & 8 && s->bits_per_sample == 16) {

                 static int warned;
                 if(!warned)
                     avpriv_request_sample(s->avctx, "CDLMS of order %d",
                                           s->cdlms[c][i].order);
                 warned = 1;
             }

         }

         for (i = 0; i < s->cdlms_ttl[c]; i++)

             s->cdlms[c][i].scaling = get_bits(&s->gb, 4);
 

         if (cdlms_send_coef) {
             for (i = 0; i < s->cdlms_ttl[c]; i++) {

                 int cbits, shift_l, shift_r, j;
                 cbits = av_log2(s->cdlms[c][i].order);

                 if ((1 << cbits) < s->cdlms[c][i].order)

                     cbits++;
                 s->cdlms[c][i].coefsend = get_bits(&s->gb, cbits) + 1;
 
                 cbits = av_log2(s->cdlms[c][i].scaling + 1);

                 if ((1 << cbits) < s->cdlms[c][i].scaling + 1)

                     cbits++;
 

                 s->cdlms[c][i].bitsend = get_bitsz(&s->gb, cbits) + 2;

                 shift_l = 32 - s->cdlms[c][i].bitsend;

                 shift_r = 32 - s->cdlms[c][i].scaling - 2;
                 for (j = 0; j < s->cdlms[c][i].coefsend; j++)

                     s->cdlms[c][i].coefs[j] =
                         (get_bits(&s->gb, s->cdlms[c][i].bitsend) << shift_l) >> shift_r;
             }
         }

 
         for (i = 0; i < s->cdlms_ttl[c]; i++)
             memset(s->cdlms[c][i].coefs + s->cdlms[c][i].order,
                    0, WMALL_COEFF_PAD_SIZE);

     }

 
     return 0;

 }
 
 static int decode_channel_residues(WmallDecodeCtx *s, int ch, int tile_size)
 {
     int i = 0;
     unsigned int ave_mean;
     s->transient[ch] = get_bits1(&s->gb);

     if (s->transient[ch]) {
         s->transient_pos[ch] = get_bits(&s->gb, av_log2(tile_size));

         if (s->transient_pos[ch])

             s->transient[ch] = 0;
         s->channel[ch].transient_counter =
             FFMAX(s->channel[ch].transient_counter, s->samples_per_frame / 2);
     } else if (s->channel[ch].transient_counter)
         s->transient[ch] = 1;

     if (s->seekable_tile) {

         ave_mean = get_bits(&s->gb, s->bits_per_sample);
         s->ave_sum[ch] = ave_mean << (s->movave_scaling + 1);

     }
 

     if (s->seekable_tile) {
         if (s->do_inter_ch_decorr)

             s->channel_residues[ch][0] = get_sbits_long(&s->gb, s->bits_per_sample + 1);

         else

             s->channel_residues[ch][0] = get_sbits_long(&s->gb, s->bits_per_sample);

         i++;

     }

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

         int quo = 0, rem, rem_bits, residue;

         while(get_bits1(&s->gb)) {

             quo++;

             if (get_bits_left(&s->gb) <= 0)
                 return -1;
         }

         if (quo >= 32)

             quo += get_bits_long(&s->gb, get_bits(&s->gb, 5) + 1);

         ave_mean = (s->ave_sum[ch] + (1 << s->movave_scaling)) >> (s->movave_scaling + 1);
         if (ave_mean <= 1)
             residue = quo;
         else {
             rem_bits = av_ceil_log2(ave_mean);

             rem      = get_bits_long(&s->gb, rem_bits);

             residue  = (quo << rem_bits) + rem;
         }

         s->ave_sum[ch] = residue + s->ave_sum[ch] -
                          (s->ave_sum[ch] >> s->movave_scaling);

         residue = (residue >> 1) ^ -(residue & 1);

         s->channel_residues[ch][i] = residue;

     }
 
     return 0;
 
 }
 

 static void decode_lpc(WmallDecodeCtx *s)

 {
     int ch, i, cbits;

     s->lpc_order   = get_bits(&s->gb, 5) + 1;

     s->lpc_scaling = get_bits(&s->gb, 4);
     s->lpc_intbits = get_bits(&s->gb, 3) + 1;
     cbits = s->lpc_scaling + s->lpc_intbits;

     for (ch = 0; ch < s->num_channels; ch++)
         for (i = 0; i < s->lpc_order; i++)

             s->lpc_coefs[ch][i] = get_sbits(&s->gb, cbits);

 }
 

 static void clear_codec_buffers(WmallDecodeCtx *s)
 {
     int ich, ilms;
 

     memset(s->acfilter_coeffs,     0, sizeof(s->acfilter_coeffs));
     memset(s->acfilter_prevvalues, 0, sizeof(s->acfilter_prevvalues));
     memset(s->lpc_coefs,           0, sizeof(s->lpc_coefs));

     memset(s->mclms_coeffs,     0, sizeof(s->mclms_coeffs));
     memset(s->mclms_coeffs_cur, 0, sizeof(s->mclms_coeffs_cur));
     memset(s->mclms_prevvalues, 0, sizeof(s->mclms_prevvalues));
     memset(s->mclms_updates,    0, sizeof(s->mclms_updates));

 
     for (ich = 0; ich < s->num_channels; ich++) {
         for (ilms = 0; ilms < s->cdlms_ttl[ich]; ilms++) {

             memset(s->cdlms[ich][ilms].coefs, 0,
                    sizeof(s->cdlms[ich][ilms].coefs));
             memset(s->cdlms[ich][ilms].lms_prevvalues, 0,
                    sizeof(s->cdlms[ich][ilms].lms_prevvalues));
             memset(s->cdlms[ich][ilms].lms_updates, 0,
                    sizeof(s->cdlms[ich][ilms].lms_updates));

         }
         s->ave_sum[ich] = 0;
     }
 }

 /**

  * @brief Reset filter parameters and transient area at new seekable tile.

  */

 static void reset_codec(WmallDecodeCtx *s)
 {
     int ich, ilms;
     s->mclms_recent = s->mclms_order * s->num_channels;

     for (ich = 0; ich < s->num_channels; ich++) {

         for (ilms = 0; ilms < s->cdlms_ttl[ich]; ilms++)

             s->cdlms[ich][ilms].recent = s->cdlms[ich][ilms].order;

         /* first sample of a seekable subframe is considered as the starting of

             a transient area which is samples_per_frame samples long */

         s->channel[ich].transient_counter = s->samples_per_frame;

         s->transient[ich]     = 1;

         s->transient_pos[ich] = 0;

     }

 }
 

 static void mclms_update(WmallDecodeCtx *s, int icoef, int *pred)

 {

     int i, j, ich, pred_error;
     int order        = s->mclms_order;

     int num_channels = s->num_channels;

     int range        = 1 << (s->bits_per_sample - 1);

 
     for (ich = 0; ich < num_channels; ich++) {

         pred_error = s->channel_residues[ich][icoef] - pred[ich];

         if (pred_error > 0) {
             for (i = 0; i < order * num_channels; i++)
                 s->mclms_coeffs[i + ich * order * num_channels] +=
                     s->mclms_updates[s->mclms_recent + i];

             for (j = 0; j < ich; j++)
                 s->mclms_coeffs_cur[ich * num_channels + j] += WMASIGN(s->channel_residues[j][icoef]);

         } else if (pred_error < 0) {
             for (i = 0; i < order * num_channels; i++)
                 s->mclms_coeffs[i + ich * order * num_channels] -=
                     s->mclms_updates[s->mclms_recent + i];

             for (j = 0; j < ich; j++)
                 s->mclms_coeffs_cur[ich * num_channels + j] -= WMASIGN(s->channel_residues[j][icoef]);

         }
     }
 
     for (ich = num_channels - 1; ich >= 0; ich--) {
         s->mclms_recent--;

         s->mclms_prevvalues[s->mclms_recent] = av_clip(s->channel_residues[ich][icoef],
             -range, range - 1);

         s->mclms_updates[s->mclms_recent] = WMASIGN(s->channel_residues[ich][icoef]);

     }
 
     if (s->mclms_recent == 0) {

         memcpy(&s->mclms_prevvalues[order * num_channels],

                s->mclms_prevvalues,

                sizeof(int32_t) * order * num_channels);

         memcpy(&s->mclms_updates[order * num_channels],

                s->mclms_updates,

                sizeof(int32_t) * order * num_channels);

         s->mclms_recent = num_channels * order;
     }
 }

 
 static void mclms_predict(WmallDecodeCtx *s, int icoef, int *pred)

 {
     int ich, i;

     int order        = s->mclms_order;

     int num_channels = s->num_channels;
 
     for (ich = 0; ich < num_channels; ich++) {

         pred[ich] = 0;

         if (!s->is_channel_coded[ich])
             continue;
         for (i = 0; i < order * num_channels; i++)

             pred[ich] += (uint32_t)s->mclms_prevvalues[i + s->mclms_recent] *

                          s->mclms_coeffs[i + order * num_channels * ich];

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

             pred[ich] += (uint32_t)s->channel_residues[i][icoef] *

                          s->mclms_coeffs_cur[i + num_channels * ich];
         pred[ich] += 1 << s->mclms_scaling - 1;
         pred[ich] >>= s->mclms_scaling;
         s->channel_residues[ich][icoef] += pred[ich];

     }
 }
 
 static void revert_mclms(WmallDecodeCtx *s, int tile_size)
 {

     int icoef, pred[WMALL_MAX_CHANNELS] = { 0 };

     for (icoef = 0; icoef < tile_size; icoef++) {

         mclms_predict(s, icoef, pred);
         mclms_update(s, icoef, pred);

     }
 }
 

 static void use_high_update_speed(WmallDecodeCtx *s, int ich)
 {
     int ilms, recent, icoef;

     for (ilms = s->cdlms_ttl[ich] - 1; ilms >= 0; ilms--) {

         recent = s->cdlms[ich][ilms].recent;

         if (s->update_speed[ich] == 16)
             continue;

         if (s->bV3RTM) {
             for (icoef = 0; icoef < s->cdlms[ich][ilms].order; icoef++)
                 s->cdlms[ich][ilms].lms_updates[icoef + recent] *= 2;
         } else {
             for (icoef = 0; icoef < s->cdlms[ich][ilms].order; icoef++)
                 s->cdlms[ich][ilms].lms_updates[icoef] *= 2;
         }
     }

     s->update_speed[ich] = 16;

 }
 
 static void use_normal_update_speed(WmallDecodeCtx *s, int ich)
 {
     int ilms, recent, icoef;

     for (ilms = s->cdlms_ttl[ich] - 1; ilms >= 0; ilms--) {

         recent = s->cdlms[ich][ilms].recent;

         if (s->update_speed[ich] == 8)
             continue;

         if (s->bV3RTM)

             for (icoef = 0; icoef < s->cdlms[ich][ilms].order; icoef++)
                 s->cdlms[ich][ilms].lms_updates[icoef + recent] /= 2;

         else

             for (icoef = 0; icoef < s->cdlms[ich][ilms].order; icoef++)
                 s->cdlms[ich][ilms].lms_updates[icoef] /= 2;
     }

     s->update_speed[ich] = 8;

 }
 

 #define CD_LMS(bits, ROUND) \
 static void lms_update ## bits (WmallDecodeCtx *s, int ich, int ilms, int input) \
 { \
     int recent = s->cdlms[ich][ilms].recent; \
     int range  = 1 << s->bits_per_sample - 1; \
     int order  = s->cdlms[ich][ilms].order; \
     int ##bits##_t *prev = (int##bits##_t *)s->cdlms[ich][ilms].lms_prevvalues; \
  \
     if (recent) \
         recent--; \
     else { \
         memcpy(prev + order, prev, (bits/8) * order); \
         memcpy(s->cdlms[ich][ilms].lms_updates + order, \
                s->cdlms[ich][ilms].lms_updates, \
                sizeof(*s->cdlms[ich][ilms].lms_updates) * order); \
         recent = order - 1; \
     } \
  \
     prev[recent] = av_clip(input, -range, range - 1); \
     s->cdlms[ich][ilms].lms_updates[recent] = WMASIGN(input) * s->update_speed[ich]; \
  \
     s->cdlms[ich][ilms].lms_updates[recent + (order >> 4)] >>= 2; \
     s->cdlms[ich][ilms].lms_updates[recent + (order >> 3)] >>= 1; \
     s->cdlms[ich][ilms].recent = recent; \
     memset(s->cdlms[ich][ilms].lms_updates + recent + order, 0, \
            sizeof(s->cdlms[ich][ilms].lms_updates) - \
            sizeof(*s->cdlms[ich][ilms].lms_updates)*(recent+order)); \
 } \
  \
 static void revert_cdlms ## bits (WmallDecodeCtx *s, int ch, \
                                   int coef_begin, int coef_end) \
 { \
     int icoef, pred, ilms, num_lms, residue, input; \
  \
     num_lms = s->cdlms_ttl[ch]; \
     for (ilms = num_lms - 1; ilms >= 0; ilms--) { \
         for (icoef = coef_begin; icoef < coef_end; icoef++) { \
             int##bits##_t *prevvalues = (int##bits##_t *)s->cdlms[ch][ilms].lms_prevvalues; \
             pred = 1 << (s->cdlms[ch][ilms].scaling - 1); \
             residue = s->channel_residues[ch][icoef]; \
             pred += s->dsp.scalarproduct_and_madd_int## bits (s->cdlms[ch][ilms].coefs, \
                                                         prevvalues + s->cdlms[ch][ilms].recent, \
                                                         s->cdlms[ch][ilms].lms_updates + \
                                                         s->cdlms[ch][ilms].recent, \
                                                         FFALIGN(s->cdlms[ch][ilms].order, ROUND), \
                                                         WMASIGN(residue)); \
             input = residue + (pred >> s->cdlms[ch][ilms].scaling); \
             lms_update ## bits(s, ch, ilms, input); \
             s->channel_residues[ch][icoef] = input; \
         } \
     } \
     if (bits <= 16) emms_c(); \

 }
 

 CD_LMS(16, WMALL_COEFF_PAD_SIZE)
 CD_LMS(32, 8)
 

 static void revert_inter_ch_decorr(WmallDecodeCtx *s, int tile_size)
 {
     if (s->num_channels != 2)
         return;

     else if (s->is_channel_coded[0] || s->is_channel_coded[1]) {

         int icoef;

         for (icoef = 0; icoef < tile_size; icoef++) {
             s->channel_residues[0][icoef] -= s->channel_residues[1][icoef] >> 1;
             s->channel_residues[1][icoef] += s->channel_residues[0][icoef];
         }
     }
 }

 static void revert_acfilter(WmallDecodeCtx *s, int tile_size)
 {

     int ich, pred, i, j;

     int16_t *filter_coeffs = s->acfilter_coeffs;

     int scaling            = s->acfilter_scaling;
     int order              = s->acfilter_order;

     for (ich = 0; ich < s->num_channels; ich++) {

         int *prevvalues = s->acfilter_prevvalues[ich];
         for (i = 0; i < order; i++) {
             pred = 0;
             for (j = 0; j < order; j++) {
                 if (i <= j)
                     pred += filter_coeffs[j] * prevvalues[j - i];
                 else
                     pred += s->channel_residues[ich][i - j - 1] * filter_coeffs[j];
             }
             pred >>= scaling;
             s->channel_residues[ich][i] += pred;
         }
         for (i = order; i < tile_size; i++) {
             pred = 0;
             for (j = 0; j < order; j++)

                 pred += (uint32_t)s->channel_residues[ich][i - j - 1] * filter_coeffs[j];

             pred >>= scaling;

             s->channel_residues[ich][i] += pred;

         }

         for (j = 0; j < order; j++)
             prevvalues[j] = s->channel_residues[ich][tile_size - j - 1];

     }
 }

 static int decode_subframe(WmallDecodeCtx *s)
 {

     int offset        = s->samples_per_frame;
     int subframe_len  = s->samples_per_frame;
     int total_samples = s->samples_per_frame * s->num_channels;

     int i, j, rawpcm_tile, padding_zeroes, res;

 
     s->subframe_offset = get_bits_count(&s->gb);
 

     /* reset channel context and find the next block offset and size

         == the next block of the channel with the smallest number of

         decoded samples */

     for (i = 0; i < s->num_channels; i++) {
         if (offset > s->channel[i].decoded_samples) {
             offset = s->channel[i].decoded_samples;
             subframe_len =
                 s->channel[i].subframe_len[s->channel[i].cur_subframe];
         }
     }
 

     /* get a list of all channels that contain the estimated block */

     s->channels_for_cur_subframe = 0;
     for (i = 0; i < s->num_channels; i++) {
         const int cur_subframe = s->channel[i].cur_subframe;

         /* subtract already processed samples */

         total_samples -= s->channel[i].decoded_samples;
 

         /* and count if there are multiple subframes that match our profile */

         if (offset == s->channel[i].decoded_samples &&
             subframe_len == s->channel[i].subframe_len[cur_subframe]) {
             total_samples -= s->channel[i].subframe_len[cur_subframe];
             s->channel[i].decoded_samples +=
                 s->channel[i].subframe_len[cur_subframe];
             s->channel_indexes_for_cur_subframe[s->channels_for_cur_subframe] = i;
             ++s->channels_for_cur_subframe;
         }
     }
 

     /* check if the frame will be complete after processing the

         estimated block */
     if (!total_samples)
         s->parsed_all_subframes = 1;
 
 
     s->seekable_tile = get_bits1(&s->gb);

     if (s->seekable_tile) {

         clear_codec_buffers(s);

         s->do_arith_coding    = get_bits1(&s->gb);

         if (s->do_arith_coding) {

             avpriv_request_sample(s->avctx, "Arithmetic coding");

             return AVERROR_PATCHWELCOME;

         }
         s->do_ac_filter       = get_bits1(&s->gb);
         s->do_inter_ch_decorr = get_bits1(&s->gb);
         s->do_mclms           = get_bits1(&s->gb);

         if (s->do_ac_filter)

             decode_ac_filter(s);

         if (s->do_mclms)

             decode_mclms(s);

         if ((res = decode_cdlms(s)) < 0)
             return res;

         s->movave_scaling = get_bits(&s->gb, 3);
         s->quant_stepsize = get_bits(&s->gb, 8) + 1;

         reset_codec(s);

     }
 
     rawpcm_tile = get_bits1(&s->gb);
 
     if (!rawpcm_tile && !s->cdlms[0][0].order) {

         av_log(s->avctx, AV_LOG_DEBUG,
                "Waiting for seekable tile\n");

         av_frame_unref(s->frame);

         return -1;

     }
 
 

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

         s->is_channel_coded[i] = 1;

     if (!rawpcm_tile) {
         for (i = 0; i < s->num_channels; i++)

             s->is_channel_coded[i] = get_bits1(&s->gb);
 

         if (s->bV3RTM) {

             // LPC
             s->do_lpc = get_bits1(&s->gb);

             if (s->do_lpc) {

                 decode_lpc(s);

                 avpriv_request_sample(s->avctx, "Expect wrong output since "
                                       "inverse LPC filter");

             }

         } else

             s->do_lpc = 0;

     }
 
 

     if (get_bits1(&s->gb))

         padding_zeroes = get_bits(&s->gb, 5);

     else

         padding_zeroes = 0;

     if (rawpcm_tile) {

         int bits = s->bits_per_sample - padding_zeroes;

         if (bits <= 0) {
             av_log(s->avctx, AV_LOG_ERROR,
                    "Invalid number of padding bits in raw PCM tile\n");
             return AVERROR_INVALIDDATA;

         }

         ff_dlog(s->avctx, "RAWPCM %d bits per sample. "

                 "total %d bits, remain=%d\n", bits,

                 bits * s->num_channels * subframe_len, get_bits_count(&s->gb));

         for (i = 0; i < s->num_channels; i++)
             for (j = 0; j < subframe_len; j++)

                 s->channel_residues[i][j] = get_sbits_long(&s->gb, bits);

     } else {

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

             if (s->is_channel_coded[i]) {
                 decode_channel_residues(s, i, subframe_len);
                 if (s->seekable_tile)
                     use_high_update_speed(s, i);
                 else
                     use_normal_update_speed(s, i);

                 if (s->bits_per_sample > 16)
                     revert_cdlms32(s, i, 0, subframe_len);
                 else
                     revert_cdlms16(s, i, 0, subframe_len);

             } else {
                 memset(s->channel_residues[i], 0, sizeof(**s->channel_residues) * subframe_len);

             }

         }
 
         if (s->do_mclms)
             revert_mclms(s, subframe_len);
         if (s->do_inter_ch_decorr)
             revert_inter_ch_decorr(s, subframe_len);
         if (s->do_ac_filter)
             revert_acfilter(s, subframe_len);
 
         /* Dequantize */
         if (s->quant_stepsize != 1)
             for (i = 0; i < s->num_channels; i++)
                 for (j = 0; j < subframe_len; j++)
                     s->channel_residues[i][j] *= s->quant_stepsize;

     }

     /* Write to proper output buffer depending on bit-depth */

     for (i = 0; i < s->channels_for_cur_subframe; i++) {
         int c = s->channel_indexes_for_cur_subframe[i];
         int subframe_len = s->channel[c].subframe_len[s->channel[c].cur_subframe];
 
         for (j = 0; j < subframe_len; j++) {
             if (s->bits_per_sample == 16) {

                 *s->samples_16[c]++ = (int16_t) s->channel_residues[c][j] << padding_zeroes;

             } else {

                 *s->samples_32[c]++ = s->channel_residues[c][j] << (padding_zeroes + 8);

             }

         }

     }

     /* handled one subframe */

     for (i = 0; i < s->channels_for_cur_subframe; i++) {
         int c = s->channel_indexes_for_cur_subframe[i];
         if (s->channel[c].cur_subframe >= s->channel[c].num_subframes) {
             av_log(s->avctx, AV_LOG_ERROR, "broken subframe\n");
             return AVERROR_INVALIDDATA;
         }

         ++s->channel[c].cur_subframe;

     }
     return 0;
 }
 
 /**

  * @brief Decode one WMA frame.
  * @param s codec context
  * @return 0 if the trailer bit indicates that this is the last frame,
  *         1 if there are additional frames

  */
 static int decode_frame(WmallDecodeCtx *s)
 {
     GetBitContext* gb = &s->gb;

     int more_frames = 0, len = 0, i, ret;

     s->frame->nb_samples = s->samples_per_frame;
     if ((ret = ff_get_buffer(s->avctx, s->frame, 0)) < 0) {

         /* return an error if no frame could be decoded at all */

         s->packet_loss = 1;

         s->frame->nb_samples = 0;

         return ret;

     }

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

         s->samples_16[i] = (int16_t *)s->frame->extended_data[i];
         s->samples_32[i] = (int32_t *)s->frame->extended_data[i];

     }

     /* get frame length */

     if (s->len_prefix)

         len = get_bits(gb, s->log2_frame_size);

     /* decode tile information */

     if ((ret = decode_tilehdr(s))) {

         s->packet_loss = 1;

         av_frame_unref(s->frame);

         return ret;

     }
 

     /* read drc info */
     if (s->dynamic_range_compression)

         s->drc_gain = get_bits(gb, 8);

     /* no idea what these are for, might be the number of samples
        that need to be skipped at the beginning or end of a stream */

     if (get_bits1(gb)) {

         int av_unused skip;

         /* usually true for the first frame */

         if (get_bits1(gb)) {
             skip = get_bits(gb, av_log2(s->samples_per_frame * 2));

             ff_dlog(s->avctx, "start skip: %i\n", skip);

         }
 

         /* sometimes true for the last frame */

         if (get_bits1(gb)) {
             skip = get_bits(gb, av_log2(s->samples_per_frame * 2));

             ff_dlog(s->avctx, "end skip: %i\n", skip);

             s->frame->nb_samples -= skip;
             if (s->frame->nb_samples <= 0)
                 return AVERROR_INVALIDDATA;

         }
 
     }
 

     /* reset subframe states */

     s->parsed_all_subframes = 0;
     for (i = 0; i < s->num_channels; i++) {
         s->channel[i].decoded_samples = 0;
         s->channel[i].cur_subframe    = 0;
     }
 

     /* decode all subframes */

     while (!s->parsed_all_subframes) {

         int decoded_samples = s->channel[0].decoded_samples;

         if (decode_subframe(s) < 0) {
             s->packet_loss = 1;

             if (s->frame->nb_samples)
                 s->frame->nb_samples = decoded_samples;

             return 0;
         }
     }
 

     ff_dlog(s->avctx, "Frame done\n");

     s->skip_frame = 0;

 
     if (s->len_prefix) {
         if (len != (get_bits_count(gb) - s->frame_offset) + 2) {

             /* FIXME: not sure if this is always an error */

             av_log(s->avctx, AV_LOG_ERROR,

                    "frame[%"PRIu32"] would have to skip %i bits\n",
                    s->frame_num,

                    len - (get_bits_count(gb) - s->frame_offset) - 1);
             s->packet_loss = 1;
             return 0;
         }
 

         /* skip the rest of the frame data */

         skip_bits_long(gb, len - (get_bits_count(gb) - s->frame_offset) - 1);
     }
 

     /* decode trailer bit */

     more_frames = get_bits1(gb);
     ++s->frame_num;
     return more_frames;
 }
 
 /**

  * @brief Calculate remaining input buffer length.
  * @param s  codec context
  * @param gb bitstream reader context
  * @return remaining size in bits

  */
 static int remaining_bits(WmallDecodeCtx *s, GetBitContext *gb)
 {
     return s->buf_bit_size - get_bits_count(gb);
 }
 
 /**

  * @brief Fill the bit reservoir with a (partial) frame.
  * @param s      codec context
  * @param gb     bitstream reader context
  * @param len    length of the partial frame
  * @param append decides whether to reset the buffer or not

  */
 static void save_bits(WmallDecodeCtx *s, GetBitContext* gb, int len,
                       int append)
 {
     int buflen;

     PutBitContext tmp;

     /* when the frame data does not need to be concatenated, the input buffer
         is reset and additional bits from the previous frame are copied

         and skipped later so that a fast byte copy is possible */
 
     if (!append) {

         s->frame_offset   = get_bits_count(gb) & 7;

         s->num_saved_bits = s->frame_offset;

         init_put_bits(&s->pb, s->frame_data, s->max_frame_size);

     }
 
     buflen = (s->num_saved_bits + len + 8) >> 3;
 

     if (len <= 0 || buflen > s->max_frame_size) {

         avpriv_request_sample(s->avctx, "Too small input buffer");

         s->packet_loss = 1;

         s->num_saved_bits = 0;

         return;
     }
 
     s->num_saved_bits += len;
     if (!append) {
         avpriv_copy_bits(&s->pb, gb->buffer + (get_bits_count(gb) >> 3),

                          s->num_saved_bits);

     } else {
         int align = 8 - (get_bits_count(gb) & 7);
         align = FFMIN(align, len);
         put_bits(&s->pb, align, get_bits(gb, align));
         len -= align;
         avpriv_copy_bits(&s->pb, gb->buffer + (get_bits_count(gb) >> 3), len);
     }
     skip_bits_long(gb, len);
 

     tmp = s->pb;
     flush_put_bits(&tmp);

 
     init_get_bits(&s->gb, s->frame_data, s->num_saved_bits);
     skip_bits(&s->gb, s->frame_offset);
 }
 

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

 {
     WmallDecodeCtx *s = avctx->priv_data;
     GetBitContext* gb  = &s->pgb;
     const uint8_t* buf = avpkt->data;
     int buf_size       = avpkt->size;

     int num_bits_prev_frame, packet_sequence_number, spliced_packet;

     s->frame->nb_samples = 0;

     if (!buf_size && s->num_saved_bits > get_bits_count(&s->gb)) {
         s->packet_done = 0;
         if (!decode_frame(s))
             s->num_saved_bits = 0;
     } else if (s->packet_done || s->packet_loss) {

         s->packet_done = 0;
 

         if (!buf_size)
             return 0;

         s->next_packet_start = buf_size - FFMIN(avctx->block_align, buf_size);
         buf_size             = FFMIN(avctx->block_align, buf_size);

         s->buf_bit_size      = buf_size << 3;

         /* parse packet header */

         init_get_bits(gb, buf, s->buf_bit_size);

         packet_sequence_number = get_bits(gb, 4);

         skip_bits(gb, 1);   // Skip seekable_frame_in_packet, currently unused

         spliced_packet = get_bits1(gb);

         if (spliced_packet)

             avpriv_request_sample(avctx, "Bitstream splicing");

         /* get number of bits that need to be added to the previous frame */

         num_bits_prev_frame = get_bits(gb, s->log2_frame_size);
 

         /* check for packet loss */

         if (!s->packet_loss &&
             ((s->packet_sequence_number + 1) & 0xF) != packet_sequence_number) {
             s->packet_loss = 1;

             av_log(avctx, AV_LOG_ERROR,
                    "Packet loss detected! seq %"PRIx8" vs %x\n",

                    s->packet_sequence_number, packet_sequence_number);
         }
         s->packet_sequence_number = packet_sequence_number;
 
         if (num_bits_prev_frame > 0) {
             int remaining_packet_bits = s->buf_bit_size - get_bits_count(gb);
             if (num_bits_prev_frame >= remaining_packet_bits) {
                 num_bits_prev_frame = remaining_packet_bits;
                 s->packet_done = 1;
             }
 

             /* Append the previous frame data to the remaining data from the
              * previous packet to create a full frame. */

             save_bits(s, gb, num_bits_prev_frame, 1);
 

             /* decode the cross packet frame if it is valid */

             if (num_bits_prev_frame < remaining_packet_bits && !s->packet_loss)

                 decode_frame(s);

         } else if (s->num_saved_bits - s->frame_offset) {

             ff_dlog(avctx, "ignoring %x previously saved bits\n",

                     s->num_saved_bits - s->frame_offset);
         }
 
         if (s->packet_loss) {

             /* Reset number of saved bits so that the decoder does not start
              * to decode incomplete frames in the s->len_prefix == 0 case. */

             s->num_saved_bits = 0;

             s->packet_loss    = 0;

             init_put_bits(&s->pb, s->frame_data, s->max_frame_size);

         }
 
     } else {
         int frame_size;
 
         s->buf_bit_size = (avpkt->size - s->next_packet_start) << 3;
         init_get_bits(gb, avpkt->data, s->buf_bit_size);
         skip_bits(gb, s->packet_offset);
 
         if (s->len_prefix && remaining_bits(s, gb) > s->log2_frame_size &&
             (frame_size = show_bits(gb, s->log2_frame_size)) &&
             frame_size <= remaining_bits(s, gb)) {
             save_bits(s, gb, frame_size, 0);

 
             if (!s->packet_loss)
                 s->packet_done = !decode_frame(s);

         } else if (!s->len_prefix
                    && s->num_saved_bits > get_bits_count(&s->gb)) {

             /* when the frames do not have a length prefix, we don't know the
              * compressed length of the individual frames however, we know what
              * part of a new packet belongs to the previous frame therefore we
              * save the incoming packet first, then we append the "previous
              * frame" data from the next packet so that we get a buffer that
              * only contains full frames */

             s->packet_done = !decode_frame(s);
         } else {
             s->packet_done = 1;

         }

     }
 

     if (remaining_bits(s, gb) < 0) {
         av_log(avctx, AV_LOG_ERROR, "Overread %d\n", -remaining_bits(s, gb));
         s->packet_loss = 1;
     }
 

     if (s->packet_done && !s->packet_loss &&
         remaining_bits(s, gb) > 0) {

         /* save the rest of the data so that it can be decoded
          * with the next packet */

         save_bits(s, gb, remaining_bits(s, gb), 0);
     }
 

     *got_frame_ptr   = s->frame->nb_samples > 0;
     av_frame_move_ref(data, s->frame);

     s->packet_offset = get_bits_count(gb) & 7;
 

     return (s->packet_loss) ? AVERROR_INVALIDDATA : buf_size ? get_bits_count(gb) >> 3 : 0;

 }
 

 static void flush(AVCodecContext *avctx)
 {
     WmallDecodeCtx *s    = avctx->priv_data;
     s->packet_loss       = 1;
     s->packet_done       = 0;
     s->num_saved_bits    = 0;
     s->frame_offset      = 0;
     s->next_packet_start = 0;
     s->cdlms[0][0].order = 0;

     s->frame->nb_samples = 0;

     init_put_bits(&s->pb, s->frame_data, s->max_frame_size);

 }

 static av_cold int decode_close(AVCodecContext *avctx)
 {
     WmallDecodeCtx *s = avctx->priv_data;
 
     av_frame_free(&s->frame);

     av_freep(&s->frame_data);

 
     return 0;
 }
 

 AVCodec ff_wmalossless_decoder = {

     .name           = "wmalossless",

     .long_name      = NULL_IF_CONFIG_SMALL("Windows Media Audio Lossless"),

     .type           = AVMEDIA_TYPE_AUDIO,

     .id             = AV_CODEC_ID_WMALOSSLESS,

     .priv_data_size = sizeof(WmallDecodeCtx),
     .init           = decode_init,

     .close          = decode_close,

     .decode         = decode_packet,

     .flush          = flush,

     .capabilities   = AV_CODEC_CAP_SUBFRAMES | AV_CODEC_CAP_DR1 | AV_CODEC_CAP_DELAY,

     .sample_fmts    = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S16P,
                                                       AV_SAMPLE_FMT_S32P,
                                                       AV_SAMPLE_FMT_NONE },

 };