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libavcodec/shorten.c

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00001 /*
00002  * Shorten decoder
00003  * Copyright (c) 2005 Jeff Muizelaar
00004  *
00005  * This file is part of Libav.
00006  *
00007  * Libav is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * Libav is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with Libav; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00029 #include <limits.h>
00030 #include "avcodec.h"
00031 #include "bytestream.h"
00032 #include "get_bits.h"
00033 #include "golomb.h"
00034 
00035 #define MAX_CHANNELS 8
00036 #define MAX_BLOCKSIZE 65535
00037 
00038 #define OUT_BUFFER_SIZE 16384
00039 
00040 #define ULONGSIZE 2
00041 
00042 #define WAVE_FORMAT_PCM 0x0001
00043 
00044 #define DEFAULT_BLOCK_SIZE 256
00045 
00046 #define TYPESIZE 4
00047 #define CHANSIZE 0
00048 #define LPCQSIZE 2
00049 #define ENERGYSIZE 3
00050 #define BITSHIFTSIZE 2
00051 
00052 #define TYPE_S16HL 3
00053 #define TYPE_S16LH 5
00054 
00055 #define NWRAP 3
00056 #define NSKIPSIZE 1
00057 
00058 #define LPCQUANT 5
00059 #define V2LPCQOFFSET (1 << LPCQUANT)
00060 
00061 #define FNSIZE 2
00062 #define FN_DIFF0        0
00063 #define FN_DIFF1        1
00064 #define FN_DIFF2        2
00065 #define FN_DIFF3        3
00066 #define FN_QUIT         4
00067 #define FN_BLOCKSIZE    5
00068 #define FN_BITSHIFT     6
00069 #define FN_QLPC         7
00070 #define FN_ZERO         8
00071 #define FN_VERBATIM     9
00072 
00074 static const uint8_t is_audio_command[10] = { 1, 1, 1, 1, 0, 0, 0, 1, 1, 0 };
00075 
00076 #define VERBATIM_CKSIZE_SIZE 5
00077 #define VERBATIM_BYTE_SIZE 8
00078 #define CANONICAL_HEADER_SIZE 44
00079 
00080 typedef struct ShortenContext {
00081     AVCodecContext *avctx;
00082     AVFrame frame;
00083     GetBitContext gb;
00084 
00085     int min_framesize, max_framesize;
00086     unsigned channels;
00087 
00088     int32_t *decoded[MAX_CHANNELS];
00089     int32_t *decoded_base[MAX_CHANNELS];
00090     int32_t *offset[MAX_CHANNELS];
00091     int *coeffs;
00092     uint8_t *bitstream;
00093     int bitstream_size;
00094     int bitstream_index;
00095     unsigned int allocated_bitstream_size;
00096     int header_size;
00097     uint8_t header[OUT_BUFFER_SIZE];
00098     int version;
00099     int cur_chan;
00100     int bitshift;
00101     int nmean;
00102     int internal_ftype;
00103     int nwrap;
00104     int blocksize;
00105     int bitindex;
00106     int32_t lpcqoffset;
00107     int got_header;
00108     int got_quit_command;
00109 } ShortenContext;
00110 
00111 static av_cold int shorten_decode_init(AVCodecContext *avctx)
00112 {
00113     ShortenContext *s = avctx->priv_data;
00114     s->avctx          = avctx;
00115     avctx->sample_fmt = AV_SAMPLE_FMT_S16;
00116 
00117     avcodec_get_frame_defaults(&s->frame);
00118     avctx->coded_frame = &s->frame;
00119 
00120     return 0;
00121 }
00122 
00123 static int allocate_buffers(ShortenContext *s)
00124 {
00125     int i, chan;
00126     int *coeffs;
00127     void *tmp_ptr;
00128 
00129     for (chan = 0; chan < s->channels; chan++) {
00130         if (FFMAX(1, s->nmean) >= UINT_MAX / sizeof(int32_t)) {
00131             av_log(s->avctx, AV_LOG_ERROR, "nmean too large\n");
00132             return AVERROR_INVALIDDATA;
00133         }
00134         if (s->blocksize + s->nwrap >= UINT_MAX / sizeof(int32_t) ||
00135             s->blocksize + s->nwrap <= (unsigned)s->nwrap) {
00136             av_log(s->avctx, AV_LOG_ERROR,
00137                    "s->blocksize + s->nwrap too large\n");
00138             return AVERROR_INVALIDDATA;
00139         }
00140 
00141         tmp_ptr =
00142             av_realloc(s->offset[chan], sizeof(int32_t) * FFMAX(1, s->nmean));
00143         if (!tmp_ptr)
00144             return AVERROR(ENOMEM);
00145         s->offset[chan] = tmp_ptr;
00146 
00147         tmp_ptr = av_realloc(s->decoded_base[chan], (s->blocksize + s->nwrap) *
00148                              sizeof(s->decoded_base[0][0]));
00149         if (!tmp_ptr)
00150             return AVERROR(ENOMEM);
00151         s->decoded_base[chan] = tmp_ptr;
00152         for (i = 0; i < s->nwrap; i++)
00153             s->decoded_base[chan][i] = 0;
00154         s->decoded[chan] = s->decoded_base[chan] + s->nwrap;
00155     }
00156 
00157     coeffs = av_realloc(s->coeffs, s->nwrap * sizeof(*s->coeffs));
00158     if (!coeffs)
00159         return AVERROR(ENOMEM);
00160     s->coeffs = coeffs;
00161 
00162     return 0;
00163 }
00164 
00165 static inline unsigned int get_uint(ShortenContext *s, int k)
00166 {
00167     if (s->version != 0)
00168         k = get_ur_golomb_shorten(&s->gb, ULONGSIZE);
00169     return get_ur_golomb_shorten(&s->gb, k);
00170 }
00171 
00172 static void fix_bitshift(ShortenContext *s, int32_t *buffer)
00173 {
00174     int i;
00175 
00176     if (s->bitshift != 0)
00177         for (i = 0; i < s->blocksize; i++)
00178             buffer[i] <<= s->bitshift;
00179 }
00180 
00181 static int init_offset(ShortenContext *s)
00182 {
00183     int32_t mean = 0;
00184     int chan, i;
00185     int nblock = FFMAX(1, s->nmean);
00186     /* initialise offset */
00187     switch (s->internal_ftype) {
00188     case TYPE_S16HL:
00189     case TYPE_S16LH:
00190         mean = 0;
00191         break;
00192     default:
00193         av_log(s->avctx, AV_LOG_ERROR, "unknown audio type");
00194         return AVERROR_INVALIDDATA;
00195     }
00196 
00197     for (chan = 0; chan < s->channels; chan++)
00198         for (i = 0; i < nblock; i++)
00199             s->offset[chan][i] = mean;
00200     return 0;
00201 }
00202 
00203 static int decode_wave_header(AVCodecContext *avctx, const uint8_t *header,
00204                               int header_size)
00205 {
00206     int len;
00207     short wave_format;
00208 
00209     if (bytestream_get_le32(&header) != MKTAG('R', 'I', 'F', 'F')) {
00210         av_log(avctx, AV_LOG_ERROR, "missing RIFF tag\n");
00211         return AVERROR_INVALIDDATA;
00212     }
00213 
00214     header += 4; /* chunk size */
00215 
00216     if (bytestream_get_le32(&header) != MKTAG('W', 'A', 'V', 'E')) {
00217         av_log(avctx, AV_LOG_ERROR, "missing WAVE tag\n");
00218         return AVERROR_INVALIDDATA;
00219     }
00220 
00221     while (bytestream_get_le32(&header) != MKTAG('f', 'm', 't', ' ')) {
00222         len     = bytestream_get_le32(&header);
00223         header += len;
00224     }
00225     len = bytestream_get_le32(&header);
00226 
00227     if (len < 16) {
00228         av_log(avctx, AV_LOG_ERROR, "fmt chunk was too short\n");
00229         return AVERROR_INVALIDDATA;
00230     }
00231 
00232     wave_format = bytestream_get_le16(&header);
00233 
00234     switch (wave_format) {
00235     case WAVE_FORMAT_PCM:
00236         break;
00237     default:
00238         av_log(avctx, AV_LOG_ERROR, "unsupported wave format\n");
00239         return AVERROR(ENOSYS);
00240     }
00241 
00242     header += 2;        // skip channels    (already got from shorten header)
00243     avctx->sample_rate = bytestream_get_le32(&header);
00244     header += 4;        // skip bit rate    (represents original uncompressed bit rate)
00245     header += 2;        // skip block align (not needed)
00246     avctx->bits_per_coded_sample = bytestream_get_le16(&header);
00247 
00248     if (avctx->bits_per_coded_sample != 16) {
00249         av_log(avctx, AV_LOG_ERROR, "unsupported number of bits per sample\n");
00250         return AVERROR(ENOSYS);
00251     }
00252 
00253     len -= 16;
00254     if (len > 0)
00255         av_log(avctx, AV_LOG_INFO, "%d header bytes unparsed\n", len);
00256 
00257     return 0;
00258 }
00259 
00260 static void interleave_buffer(int16_t *samples, int nchan, int blocksize,
00261                               int32_t **buffer)
00262 {
00263     int i, chan;
00264     for (i=0; i<blocksize; i++)
00265         for (chan=0; chan < nchan; chan++)
00266             *samples++ = av_clip_int16(buffer[chan][i]);
00267 }
00268 
00269 static const int fixed_coeffs[3][3] = {
00270     { 1,  0,  0 },
00271     { 2, -1,  0 },
00272     { 3, -3,  1 }
00273 };
00274 
00275 static int decode_subframe_lpc(ShortenContext *s, int command, int channel,
00276                                int residual_size, int32_t coffset)
00277 {
00278     int pred_order, sum, qshift, init_sum, i, j;
00279     const int *coeffs;
00280 
00281     if (command == FN_QLPC) {
00282         /* read/validate prediction order */
00283         pred_order = get_ur_golomb_shorten(&s->gb, LPCQSIZE);
00284         if (pred_order > s->nwrap) {
00285             av_log(s->avctx, AV_LOG_ERROR, "invalid pred_order %d\n",
00286                    pred_order);
00287             return AVERROR(EINVAL);
00288         }
00289         /* read LPC coefficients */
00290         for (i = 0; i < pred_order; i++)
00291             s->coeffs[i] = get_sr_golomb_shorten(&s->gb, LPCQUANT);
00292         coeffs = s->coeffs;
00293 
00294         qshift = LPCQUANT;
00295     } else {
00296         /* fixed LPC coeffs */
00297         pred_order = command;
00298         coeffs     = fixed_coeffs[pred_order - 1];
00299         qshift     = 0;
00300     }
00301 
00302     /* subtract offset from previous samples to use in prediction */
00303     if (command == FN_QLPC && coffset)
00304         for (i = -pred_order; i < 0; i++)
00305             s->decoded[channel][i] -= coffset;
00306 
00307     /* decode residual and do LPC prediction */
00308     init_sum = pred_order ? (command == FN_QLPC ? s->lpcqoffset : 0) : coffset;
00309     for (i = 0; i < s->blocksize; i++) {
00310         sum = init_sum;
00311         for (j = 0; j < pred_order; j++)
00312             sum += coeffs[j] * s->decoded[channel][i - j - 1];
00313         s->decoded[channel][i] = get_sr_golomb_shorten(&s->gb, residual_size) +
00314                                  (sum >> qshift);
00315     }
00316 
00317     /* add offset to current samples */
00318     if (command == FN_QLPC && coffset)
00319         for (i = 0; i < s->blocksize; i++)
00320             s->decoded[channel][i] += coffset;
00321 
00322     return 0;
00323 }
00324 
00325 static int read_header(ShortenContext *s)
00326 {
00327     int i, ret;
00328     int maxnlpc = 0;
00329     /* shorten signature */
00330     if (get_bits_long(&s->gb, 32) != AV_RB32("ajkg")) {
00331         av_log(s->avctx, AV_LOG_ERROR, "missing shorten magic 'ajkg'\n");
00332         return AVERROR_INVALIDDATA;
00333     }
00334 
00335     s->lpcqoffset     = 0;
00336     s->blocksize      = DEFAULT_BLOCK_SIZE;
00337     s->nmean          = -1;
00338     s->version        = get_bits(&s->gb, 8);
00339     s->internal_ftype = get_uint(s, TYPESIZE);
00340 
00341     s->channels = get_uint(s, CHANSIZE);
00342     if (!s->channels) {
00343         av_log(s->avctx, AV_LOG_ERROR, "No channels reported\n");
00344         return AVERROR_INVALIDDATA;
00345     }
00346     if (s->channels > MAX_CHANNELS) {
00347         av_log(s->avctx, AV_LOG_ERROR, "too many channels: %d\n", s->channels);
00348         s->channels = 0;
00349         return AVERROR_INVALIDDATA;
00350     }
00351     s->avctx->channels = s->channels;
00352 
00353     /* get blocksize if version > 0 */
00354     if (s->version > 0) {
00355         int skip_bytes;
00356         unsigned blocksize;
00357 
00358         blocksize = get_uint(s, av_log2(DEFAULT_BLOCK_SIZE));
00359         if (!blocksize || blocksize > MAX_BLOCKSIZE) {
00360             av_log(s->avctx, AV_LOG_ERROR,
00361                    "invalid or unsupported block size: %d\n",
00362                    blocksize);
00363             return AVERROR(EINVAL);
00364         }
00365         s->blocksize = blocksize;
00366 
00367         maxnlpc  = get_uint(s, LPCQSIZE);
00368         s->nmean = get_uint(s, 0);
00369 
00370         skip_bytes = get_uint(s, NSKIPSIZE);
00371         for (i = 0; i < skip_bytes; i++)
00372             skip_bits(&s->gb, 8);
00373     }
00374     s->nwrap = FFMAX(NWRAP, maxnlpc);
00375 
00376     if ((ret = allocate_buffers(s)) < 0)
00377         return ret;
00378 
00379     if ((ret = init_offset(s)) < 0)
00380         return ret;
00381 
00382     if (s->version > 1)
00383         s->lpcqoffset = V2LPCQOFFSET;
00384 
00385     if (get_ur_golomb_shorten(&s->gb, FNSIZE) != FN_VERBATIM) {
00386         av_log(s->avctx, AV_LOG_ERROR,
00387                "missing verbatim section at beginning of stream\n");
00388         return AVERROR_INVALIDDATA;
00389     }
00390 
00391     s->header_size = get_ur_golomb_shorten(&s->gb, VERBATIM_CKSIZE_SIZE);
00392     if (s->header_size >= OUT_BUFFER_SIZE ||
00393         s->header_size < CANONICAL_HEADER_SIZE) {
00394         av_log(s->avctx, AV_LOG_ERROR, "header is wrong size: %d\n",
00395                s->header_size);
00396         return AVERROR_INVALIDDATA;
00397     }
00398 
00399     for (i = 0; i < s->header_size; i++)
00400         s->header[i] = (char)get_ur_golomb_shorten(&s->gb, VERBATIM_BYTE_SIZE);
00401 
00402     if ((ret = decode_wave_header(s->avctx, s->header, s->header_size)) < 0)
00403         return ret;
00404 
00405     s->cur_chan = 0;
00406     s->bitshift = 0;
00407 
00408     s->got_header = 1;
00409 
00410     return 0;
00411 }
00412 
00413 static int shorten_decode_frame(AVCodecContext *avctx, void *data,
00414                                 int *got_frame_ptr, AVPacket *avpkt)
00415 {
00416     const uint8_t *buf = avpkt->data;
00417     int buf_size       = avpkt->size;
00418     ShortenContext *s  = avctx->priv_data;
00419     int i, input_buf_size = 0;
00420     int ret;
00421 
00422     /* allocate internal bitstream buffer */
00423     if (s->max_framesize == 0) {
00424         void *tmp_ptr;
00425         s->max_framesize = 1024; // should hopefully be enough for the first header
00426         tmp_ptr = av_fast_realloc(s->bitstream, &s->allocated_bitstream_size,
00427                                   s->max_framesize);
00428         if (!tmp_ptr) {
00429             av_log(avctx, AV_LOG_ERROR, "error allocating bitstream buffer\n");
00430             return AVERROR(ENOMEM);
00431         }
00432         s->bitstream = tmp_ptr;
00433     }
00434 
00435     /* append current packet data to bitstream buffer */
00436     if (1 && s->max_framesize) { //FIXME truncated
00437         buf_size       = FFMIN(buf_size, s->max_framesize - s->bitstream_size);
00438         input_buf_size = buf_size;
00439 
00440         if (s->bitstream_index + s->bitstream_size + buf_size >
00441             s->allocated_bitstream_size) {
00442             memmove(s->bitstream, &s->bitstream[s->bitstream_index],
00443                     s->bitstream_size);
00444             s->bitstream_index = 0;
00445         }
00446         if (buf)
00447             memcpy(&s->bitstream[s->bitstream_index + s->bitstream_size], buf,
00448                    buf_size);
00449         buf               = &s->bitstream[s->bitstream_index];
00450         buf_size         += s->bitstream_size;
00451         s->bitstream_size = buf_size;
00452 
00453         /* do not decode until buffer has at least max_framesize bytes or
00454          * the end of the file has been reached */
00455         if (buf_size < s->max_framesize && avpkt->data) {
00456             *got_frame_ptr = 0;
00457             return input_buf_size;
00458         }
00459     }
00460     /* init and position bitstream reader */
00461     init_get_bits(&s->gb, buf, buf_size * 8);
00462     skip_bits(&s->gb, s->bitindex);
00463 
00464     /* process header or next subblock */
00465     if (!s->got_header) {
00466         if ((ret = read_header(s)) < 0)
00467             return ret;
00468         *got_frame_ptr = 0;
00469         goto finish_frame;
00470     }
00471 
00472     /* if quit command was read previously, don't decode anything */
00473     if (s->got_quit_command) {
00474         *got_frame_ptr = 0;
00475         return avpkt->size;
00476     }
00477 
00478     s->cur_chan = 0;
00479     while (s->cur_chan < s->channels) {
00480         int cmd;
00481         int len;
00482 
00483         if (get_bits_left(&s->gb) < 3 + FNSIZE) {
00484             *got_frame_ptr = 0;
00485             break;
00486         }
00487 
00488         cmd = get_ur_golomb_shorten(&s->gb, FNSIZE);
00489 
00490         if (cmd > FN_VERBATIM) {
00491             av_log(avctx, AV_LOG_ERROR, "unknown shorten function %d\n", cmd);
00492             *got_frame_ptr = 0;
00493             break;
00494         }
00495 
00496         if (!is_audio_command[cmd]) {
00497             /* process non-audio command */
00498             switch (cmd) {
00499             case FN_VERBATIM:
00500                 len = get_ur_golomb_shorten(&s->gb, VERBATIM_CKSIZE_SIZE);
00501                 while (len--)
00502                     get_ur_golomb_shorten(&s->gb, VERBATIM_BYTE_SIZE);
00503                 break;
00504             case FN_BITSHIFT:
00505                 s->bitshift = get_ur_golomb_shorten(&s->gb, BITSHIFTSIZE);
00506                 break;
00507             case FN_BLOCKSIZE: {
00508                 unsigned blocksize = get_uint(s, av_log2(s->blocksize));
00509                 if (blocksize > s->blocksize) {
00510                     av_log(avctx, AV_LOG_ERROR,
00511                            "Increasing block size is not supported\n");
00512                     return AVERROR_PATCHWELCOME;
00513                 }
00514                 if (!blocksize || blocksize > MAX_BLOCKSIZE) {
00515                     av_log(avctx, AV_LOG_ERROR, "invalid or unsupported "
00516                                                 "block size: %d\n", blocksize);
00517                     return AVERROR(EINVAL);
00518                 }
00519                 s->blocksize = blocksize;
00520                 break;
00521             }
00522             case FN_QUIT:
00523                 s->got_quit_command = 1;
00524                 break;
00525             }
00526             if (cmd == FN_BLOCKSIZE || cmd == FN_QUIT) {
00527                 *got_frame_ptr = 0;
00528                 break;
00529             }
00530         } else {
00531             /* process audio command */
00532             int residual_size = 0;
00533             int channel = s->cur_chan;
00534             int32_t coffset;
00535 
00536             /* get Rice code for residual decoding */
00537             if (cmd != FN_ZERO) {
00538                 residual_size = get_ur_golomb_shorten(&s->gb, ENERGYSIZE);
00539                 /* this is a hack as version 0 differed in defintion of get_sr_golomb_shorten */
00540                 if (s->version == 0)
00541                     residual_size--;
00542             }
00543 
00544             /* calculate sample offset using means from previous blocks */
00545             if (s->nmean == 0)
00546                 coffset = s->offset[channel][0];
00547             else {
00548                 int32_t sum = (s->version < 2) ? 0 : s->nmean / 2;
00549                 for (i = 0; i < s->nmean; i++)
00550                     sum += s->offset[channel][i];
00551                 coffset = sum / s->nmean;
00552                 if (s->version >= 2)
00553                     coffset >>= FFMIN(1, s->bitshift);
00554             }
00555 
00556             /* decode samples for this channel */
00557             if (cmd == FN_ZERO) {
00558                 for (i = 0; i < s->blocksize; i++)
00559                     s->decoded[channel][i] = 0;
00560             } else {
00561                 if ((ret = decode_subframe_lpc(s, cmd, channel,
00562                                                residual_size, coffset)) < 0)
00563                     return ret;
00564             }
00565 
00566             /* update means with info from the current block */
00567             if (s->nmean > 0) {
00568                 int32_t sum = (s->version < 2) ? 0 : s->blocksize / 2;
00569                 for (i = 0; i < s->blocksize; i++)
00570                     sum += s->decoded[channel][i];
00571 
00572                 for (i = 1; i < s->nmean; i++)
00573                     s->offset[channel][i - 1] = s->offset[channel][i];
00574 
00575                 if (s->version < 2)
00576                     s->offset[channel][s->nmean - 1] = sum / s->blocksize;
00577                 else
00578                     s->offset[channel][s->nmean - 1] = (sum / s->blocksize) << s->bitshift;
00579             }
00580 
00581             /* copy wrap samples for use with next block */
00582             for (i = -s->nwrap; i < 0; i++)
00583                 s->decoded[channel][i] = s->decoded[channel][i + s->blocksize];
00584 
00585             /* shift samples to add in unused zero bits which were removed
00586              * during encoding */
00587             fix_bitshift(s, s->decoded[channel]);
00588 
00589             /* if this is the last channel in the block, output the samples */
00590             s->cur_chan++;
00591             if (s->cur_chan == s->channels) {
00592                 /* get output buffer */
00593                 s->frame.nb_samples = s->blocksize;
00594                 if ((ret = avctx->get_buffer(avctx, &s->frame)) < 0) {
00595                     av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00596                     return ret;
00597                 }
00598                 /* interleave output */
00599                 interleave_buffer((int16_t *)s->frame.data[0], s->channels,
00600                                   s->blocksize, s->decoded);
00601 
00602                 *got_frame_ptr   = 1;
00603                 *(AVFrame *)data = s->frame;
00604             }
00605         }
00606     }
00607     if (s->cur_chan < s->channels)
00608         *got_frame_ptr = 0;
00609 
00610 finish_frame:
00611     s->bitindex = get_bits_count(&s->gb) - 8 * (get_bits_count(&s->gb) / 8);
00612     i           = get_bits_count(&s->gb) / 8;
00613     if (i > buf_size) {
00614         av_log(s->avctx, AV_LOG_ERROR, "overread: %d\n", i - buf_size);
00615         s->bitstream_size  = 0;
00616         s->bitstream_index = 0;
00617         return AVERROR_INVALIDDATA;
00618     }
00619     if (s->bitstream_size) {
00620         s->bitstream_index += i;
00621         s->bitstream_size  -= i;
00622         return input_buf_size;
00623     } else
00624         return i;
00625 }
00626 
00627 static av_cold int shorten_decode_close(AVCodecContext *avctx)
00628 {
00629     ShortenContext *s = avctx->priv_data;
00630     int i;
00631 
00632     for (i = 0; i < s->channels; i++) {
00633         s->decoded[i] = NULL;
00634         av_freep(&s->decoded_base[i]);
00635         av_freep(&s->offset[i]);
00636     }
00637     av_freep(&s->bitstream);
00638     av_freep(&s->coeffs);
00639 
00640     return 0;
00641 }
00642 
00643 AVCodec ff_shorten_decoder = {
00644     .name           = "shorten",
00645     .type           = AVMEDIA_TYPE_AUDIO,
00646     .id             = CODEC_ID_SHORTEN,
00647     .priv_data_size = sizeof(ShortenContext),
00648     .init           = shorten_decode_init,
00649     .close          = shorten_decode_close,
00650     .decode         = shorten_decode_frame,
00651     .capabilities   = CODEC_CAP_DELAY | CODEC_CAP_DR1,
00652     .long_name= NULL_IF_CONFIG_SMALL("Shorten"),
00653 };
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