libavcodec/shorten.c

   1 /*
   2  * Shorten decoder
   3  * Copyright (c) 2005 Jeff Muizelaar
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * Libav is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with Libav; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file
  24  * Shorten decoder
  25  * @author Jeff Muizelaar
  26  *
  27  */
  28
  29 #include <limits.h>
  30 #include "avcodec.h"
  31 #include "bytestream.h"
  32 #include "get_bits.h"
  33 #include "golomb.h"
  34 #include "internal.h"
  35
  36 #define MAX_CHANNELS 8
  37 #define MAX_BLOCKSIZE 65535
  38
  39 #define OUT_BUFFER_SIZE 16384
  40
  41 #define ULONGSIZE 2
  42
  43 #define WAVE_FORMAT_PCM 0x0001
  44
  45 #define DEFAULT_BLOCK_SIZE 256
  46
  47 #define TYPESIZE 4
  48 #define CHANSIZE 0
  49 #define LPCQSIZE 2
  50 #define ENERGYSIZE 3
  51 #define BITSHIFTSIZE 2
  52
  53 #define TYPE_S16HL 3
  54 #define TYPE_S16LH 5
  55
  56 #define NWRAP 3
  57 #define NSKIPSIZE 1
  58
  59 #define LPCQUANT 5
  60 #define V2LPCQOFFSET (1 << LPCQUANT)
  61
  62 #define FNSIZE 2
  63 #define FN_DIFF0        0
  64 #define FN_DIFF1        1
  65 #define FN_DIFF2        2
  66 #define FN_DIFF3        3
  67 #define FN_QUIT         4
  68 #define FN_BLOCKSIZE    5
  69 #define FN_BITSHIFT     6
  70 #define FN_QLPC         7
  71 #define FN_ZERO         8
  72 #define FN_VERBATIM     9
  73
  74 /** indicates if the FN_* command is audio or non-audio */
  75 static const uint8_t is_audio_command[10] = { 1, 1, 1, 1, 0, 0, 0, 1, 1, 0 };
  76
  77 #define VERBATIM_CKSIZE_SIZE 5
  78 #define VERBATIM_BYTE_SIZE 8
  79 #define CANONICAL_HEADER_SIZE 44
  80
  81 typedef struct ShortenContext {
  82     AVCodecContext *avctx;
  83     AVFrame frame;
  84     GetBitContext gb;
  85
  86     int min_framesize, max_framesize;
  87     int channels;
  88
  89     int32_t *decoded[MAX_CHANNELS];
  90     int32_t *decoded_base[MAX_CHANNELS];
  91     int32_t *offset[MAX_CHANNELS];
  92     int *coeffs;
  93     uint8_t *bitstream;
  94     int bitstream_size;
  95     int bitstream_index;
  96     unsigned int allocated_bitstream_size;
  97     int header_size;
  98     uint8_t header[OUT_BUFFER_SIZE];
  99     int version;
 100     int cur_chan;
 101     int bitshift;
 102     int nmean;
 103     int internal_ftype;
 104     int nwrap;
 105     int blocksize;
 106     int bitindex;
 107     int32_t lpcqoffset;
 108     int got_header;
 109     int got_quit_command;
 110 } ShortenContext;
 111
 112 static av_cold int shorten_decode_init(AVCodecContext * avctx)
 113 {
 114     ShortenContext *s = avctx->priv_data;
 115     s->avctx = avctx;
 116     avctx->sample_fmt = AV_SAMPLE_FMT_S16P;
 117
 118     avcodec_get_frame_defaults(&s->frame);
 119     avctx->coded_frame = &s->frame;
 120
 121     return 0;
 122 }
 123
 124 static int allocate_buffers(ShortenContext *s)
 125 {
 126     int i, chan;
 127     int *coeffs;
 128     void *tmp_ptr;
 129
 130     for (chan=0; chan<s->channels; chan++) {
 131         if(FFMAX(1, s->nmean) >= UINT_MAX/sizeof(int32_t)){
 132             av_log(s->avctx, AV_LOG_ERROR, "nmean too large\n");
 133             return -1;
 134         }
 135         if(s->blocksize + s->nwrap >= UINT_MAX/sizeof(int32_t) || s->blocksize + s->nwrap <= (unsigned)s->nwrap){
 136             av_log(s->avctx, AV_LOG_ERROR, "s->blocksize + s->nwrap too large\n");
 137             return -1;
 138         }
 139
 140         tmp_ptr = av_realloc(s->offset[chan], sizeof(int32_t)*FFMAX(1, s->nmean));
 141         if (!tmp_ptr)
 142             return AVERROR(ENOMEM);
 143         s->offset[chan] = tmp_ptr;
 144
 145         tmp_ptr = av_realloc(s->decoded_base[chan], (s->blocksize + s->nwrap) *
 146                              sizeof(s->decoded_base[0][0]));
 147         if (!tmp_ptr)
 148             return AVERROR(ENOMEM);
 149         s->decoded_base[chan] = tmp_ptr;
 150         for (i=0; i<s->nwrap; i++)
 151             s->decoded_base[chan][i] = 0;
 152         s->decoded[chan] = s->decoded_base[chan] + s->nwrap;
 153     }
 154
 155     coeffs = av_realloc(s->coeffs, s->nwrap * sizeof(*s->coeffs));
 156     if (!coeffs)
 157         return AVERROR(ENOMEM);
 158     s->coeffs = coeffs;
 159
 160     return 0;
 161 }
 162
 163
 164 static inline unsigned int get_uint(ShortenContext *s, int k)
 165 {
 166     if (s->version != 0)
 167         k = get_ur_golomb_shorten(&s->gb, ULONGSIZE);
 168     return get_ur_golomb_shorten(&s->gb, k);
 169 }
 170
 171
 172 static void fix_bitshift(ShortenContext *s, int32_t *buffer)
 173 {
 174     int i;
 175
 176     if (s->bitshift != 0)
 177         for (i = 0; i < s->blocksize; i++)
 178             buffer[i] <<= s->bitshift;
 179 }
 180
 181
 182 static int init_offset(ShortenContext *s)
 183 {
 184     int32_t mean = 0;
 185     int  chan, i;
 186     int nblock = FFMAX(1, s->nmean);
 187     /* initialise offset */
 188     switch (s->internal_ftype)
 189     {
 190         case TYPE_S16HL:
 191         case TYPE_S16LH:
 192             mean = 0;
 193             break;
 194         default:
 195             av_log(s->avctx, AV_LOG_ERROR, "unknown audio type");
 196             return AVERROR_INVALIDDATA;
 197     }
 198
 199     for (chan = 0; chan < s->channels; chan++)
 200         for (i = 0; i < nblock; i++)
 201             s->offset[chan][i] = mean;
 202     return 0;
 203 }
 204
 205 static int decode_wave_header(AVCodecContext *avctx, const uint8_t *header,
 206                               int header_size)
 207 {
 208     int len;
 209     short wave_format;
 210
 211
 212     if (bytestream_get_le32(&header) != MKTAG('R','I','F','F')) {
 213         av_log(avctx, AV_LOG_ERROR, "missing RIFF tag\n");
 214         return -1;
 215     }
 216
 217     header += 4; /* chunk size */;
 218
 219     if (bytestream_get_le32(&header) != MKTAG('W','A','V','E')) {
 220         av_log(avctx, AV_LOG_ERROR, "missing WAVE tag\n");
 221         return -1;
 222     }
 223
 224     while (bytestream_get_le32(&header) != MKTAG('f','m','t',' ')) {
 225         len = bytestream_get_le32(&header);
 226         header += len;
 227     }
 228     len = bytestream_get_le32(&header);
 229
 230     if (len < 16) {
 231         av_log(avctx, AV_LOG_ERROR, "fmt chunk was too short\n");
 232         return -1;
 233     }
 234
 235     wave_format = bytestream_get_le16(&header);
 236
 237     switch (wave_format) {
 238         case WAVE_FORMAT_PCM:
 239             break;
 240         default:
 241             av_log(avctx, AV_LOG_ERROR, "unsupported wave format\n");
 242             return -1;
 243     }
 244
 245     header += 2;        // skip channels    (already got from shorten header)
 246     avctx->sample_rate = bytestream_get_le32(&header);
 247     header += 4;        // skip bit rate    (represents original uncompressed bit rate)
 248     header += 2;        // skip block align (not needed)
 249     avctx->bits_per_coded_sample = bytestream_get_le16(&header);
 250
 251     if (avctx->bits_per_coded_sample != 16) {
 252         av_log(avctx, AV_LOG_ERROR, "unsupported number of bits per sample\n");
 253         return -1;
 254     }
 255
 256     len -= 16;
 257     if (len > 0)
 258         av_log(avctx, AV_LOG_INFO, "%d header bytes unparsed\n", len);
 259
 260     return 0;
 261 }
 262
 263 static void output_buffer(int16_t **samples, int nchan, int blocksize,
 264                           int32_t **buffer)
 265 {
 266     int i, ch;
 267     for (ch = 0; ch < nchan; ch++) {
 268         int32_t *in  = buffer[ch];
 269         int16_t *out = samples[ch];
 270         for (i = 0; i < blocksize; i++)
 271             out[i] = av_clip_int16(in[i]);
 272     }
 273 }
 274
 275 static const int fixed_coeffs[3][3] = {
 276     { 1,  0,  0 },
 277     { 2, -1,  0 },
 278     { 3, -3,  1 }
 279 };
 280
 281 static int decode_subframe_lpc(ShortenContext *s, int command, int channel,
 282                                int residual_size, int32_t coffset)
 283 {
 284     int pred_order, sum, qshift, init_sum, i, j;
 285     const int *coeffs;
 286
 287     if (command == FN_QLPC) {
 288         /* read/validate prediction order */
 289         pred_order = get_ur_golomb_shorten(&s->gb, LPCQSIZE);
 290         if (pred_order > s->nwrap) {
 291             av_log(s->avctx, AV_LOG_ERROR, "invalid pred_order %d\n", pred_order);
 292             return AVERROR(EINVAL);
 293         }
 294         /* read LPC coefficients */
 295         for (i=0; i<pred_order; i++)
 296             s->coeffs[i] = get_sr_golomb_shorten(&s->gb, LPCQUANT);
 297         coeffs = s->coeffs;
 298
 299         qshift = LPCQUANT;
 300     } else {
 301         /* fixed LPC coeffs */
 302         pred_order = command;
 303         coeffs     = fixed_coeffs[pred_order-1];
 304         qshift     = 0;
 305     }
 306
 307     /* subtract offset from previous samples to use in prediction */
 308     if (command == FN_QLPC && coffset)
 309         for (i = -pred_order; i < 0; i++)
 310             s->decoded[channel][i] -= coffset;
 311
 312     /* decode residual and do LPC prediction */
 313     init_sum = pred_order ? (command == FN_QLPC ? s->lpcqoffset : 0) : coffset;
 314     for (i=0; i < s->blocksize; i++) {
 315         sum = init_sum;
 316         for (j=0; j<pred_order; j++)
 317             sum += coeffs[j] * s->decoded[channel][i-j-1];
 318         s->decoded[channel][i] = get_sr_golomb_shorten(&s->gb, residual_size) + (sum >> qshift);
 319     }
 320
 321     /* add offset to current samples */
 322     if (command == FN_QLPC && coffset)
 323         for (i = 0; i < s->blocksize; i++)
 324             s->decoded[channel][i] += coffset;
 325
 326     return 0;
 327 }
 328
 329 static int read_header(ShortenContext *s)
 330 {
 331     int i, ret;
 332     int maxnlpc = 0;
 333     /* shorten signature */
 334     if (get_bits_long(&s->gb, 32) != AV_RB32("ajkg")) {
 335         av_log(s->avctx, AV_LOG_ERROR, "missing shorten magic 'ajkg'\n");
 336         return -1;
 337     }
 338
 339     s->lpcqoffset = 0;
 340     s->blocksize = DEFAULT_BLOCK_SIZE;
 341     s->nmean = -1;
 342     s->version = get_bits(&s->gb, 8);
 343     s->internal_ftype = get_uint(s, TYPESIZE);
 344
 345     s->channels = get_uint(s, CHANSIZE);
 346     if (s->channels <= 0 || s->channels > MAX_CHANNELS) {
 347         av_log(s->avctx, AV_LOG_ERROR, "too many channels: %d\n", s->channels);
 348         return -1;
 349     }
 350     s->avctx->channels = s->channels;
 351
 352     /* get blocksize if version > 0 */
 353     if (s->version > 0) {
 354         int skip_bytes, blocksize;
 355
 356         blocksize = get_uint(s, av_log2(DEFAULT_BLOCK_SIZE));
 357         if (!blocksize || blocksize > MAX_BLOCKSIZE) {
 358             av_log(s->avctx, AV_LOG_ERROR, "invalid or unsupported block size: %d\n",
 359                    blocksize);
 360             return AVERROR(EINVAL);
 361         }
 362         s->blocksize = blocksize;
 363
 364         maxnlpc = get_uint(s, LPCQSIZE);
 365         s->nmean = get_uint(s, 0);
 366
 367         skip_bytes = get_uint(s, NSKIPSIZE);
 368         for (i=0; i<skip_bytes; i++) {
 369             skip_bits(&s->gb, 8);
 370         }
 371     }
 372     s->nwrap = FFMAX(NWRAP, maxnlpc);
 373
 374     if ((ret = allocate_buffers(s)) < 0)
 375         return ret;
 376
 377     if ((ret = init_offset(s)) < 0)
 378         return ret;
 379
 380     if (s->version > 1)
 381         s->lpcqoffset = V2LPCQOFFSET;
 382
 383     if (get_ur_golomb_shorten(&s->gb, FNSIZE) != FN_VERBATIM) {
 384         av_log(s->avctx, AV_LOG_ERROR, "missing verbatim section at beginning of stream\n");
 385         return -1;
 386     }
 387
 388     s->header_size = get_ur_golomb_shorten(&s->gb, VERBATIM_CKSIZE_SIZE);
 389     if (s->header_size >= OUT_BUFFER_SIZE || s->header_size < CANONICAL_HEADER_SIZE) {
 390         av_log(s->avctx, AV_LOG_ERROR, "header is wrong size: %d\n", s->header_size);
 391         return -1;
 392     }
 393
 394     for (i=0; i<s->header_size; i++)
 395         s->header[i] = (char)get_ur_golomb_shorten(&s->gb, VERBATIM_BYTE_SIZE);
 396
 397     if (decode_wave_header(s->avctx, s->header, s->header_size) < 0)
 398         return -1;
 399
 400     s->cur_chan = 0;
 401     s->bitshift = 0;
 402
 403     s->got_header = 1;
 404
 405     return 0;
 406 }
 407
 408 static int shorten_decode_frame(AVCodecContext *avctx, void *data,
 409                                 int *got_frame_ptr, AVPacket *avpkt)
 410 {
 411     const uint8_t *buf = avpkt->data;
 412     int buf_size = avpkt->size;
 413     ShortenContext *s = avctx->priv_data;
 414     int i, input_buf_size = 0;
 415     int ret;
 416
 417     /* allocate internal bitstream buffer */
 418     if(s->max_framesize == 0){
 419         void *tmp_ptr;
 420         s->max_framesize= 1024; // should hopefully be enough for the first header
 421         tmp_ptr = av_fast_realloc(s->bitstream, &s->allocated_bitstream_size,
 422                                   s->max_framesize);
 423         if (!tmp_ptr) {
 424             av_log(avctx, AV_LOG_ERROR, "error allocating bitstream buffer\n");
 425             return AVERROR(ENOMEM);
 426         }
 427         s->bitstream = tmp_ptr;
 428     }
 429
 430     /* append current packet data to bitstream buffer */
 431     if(1 && s->max_framesize){//FIXME truncated
 432         buf_size= FFMIN(buf_size, s->max_framesize - s->bitstream_size);
 433         input_buf_size= buf_size;
 434
 435         if(s->bitstream_index + s->bitstream_size + buf_size > s->allocated_bitstream_size){
 436             memmove(s->bitstream, &s->bitstream[s->bitstream_index], s->bitstream_size);
 437             s->bitstream_index=0;
 438         }
 439         if (buf)
 440             memcpy(&s->bitstream[s->bitstream_index + s->bitstream_size], buf, buf_size);
 441         buf= &s->bitstream[s->bitstream_index];
 442         buf_size += s->bitstream_size;
 443         s->bitstream_size= buf_size;
 444
 445         /* do not decode until buffer has at least max_framesize bytes or
 446            the end of the file has been reached */
 447         if (buf_size < s->max_framesize && avpkt->data) {
 448             *got_frame_ptr = 0;
 449             return input_buf_size;
 450         }
 451     }
 452     /* init and position bitstream reader */
 453     init_get_bits(&s->gb, buf, buf_size*8);
 454     skip_bits(&s->gb, s->bitindex);
 455
 456     /* process header or next subblock */
 457     if (!s->got_header) {
 458         if ((ret = read_header(s)) < 0)
 459             return ret;
 460         *got_frame_ptr = 0;
 461         goto finish_frame;
 462     }
 463
 464     /* if quit command was read previously, don't decode anything */
 465     if (s->got_quit_command) {
 466         *got_frame_ptr = 0;
 467         return avpkt->size;
 468     }
 469
 470     s->cur_chan = 0;
 471     while (s->cur_chan < s->channels) {
 472         unsigned cmd;
 473         int len;
 474
 475         if (get_bits_left(&s->gb) < 3+FNSIZE) {
 476             *got_frame_ptr = 0;
 477             break;
 478         }
 479
 480         cmd = get_ur_golomb_shorten(&s->gb, FNSIZE);
 481
 482         if (cmd > FN_VERBATIM) {
 483             av_log(avctx, AV_LOG_ERROR, "unknown shorten function %d\n", cmd);
 484             *got_frame_ptr = 0;
 485             break;
 486         }
 487
 488         if (!is_audio_command[cmd]) {
 489             /* process non-audio command */
 490             switch (cmd) {
 491                 case FN_VERBATIM:
 492                     len = get_ur_golomb_shorten(&s->gb, VERBATIM_CKSIZE_SIZE);
 493                     while (len--) {
 494                         get_ur_golomb_shorten(&s->gb, VERBATIM_BYTE_SIZE);
 495                     }
 496                     break;
 497                 case FN_BITSHIFT:
 498                     s->bitshift = get_ur_golomb_shorten(&s->gb, BITSHIFTSIZE);
 499                     break;
 500                 case FN_BLOCKSIZE: {
 501                     int blocksize = get_uint(s, av_log2(s->blocksize));
 502                     if (blocksize > s->blocksize) {
 503                         av_log(avctx, AV_LOG_ERROR, "Increasing block size is not supported\n");
 504                         return AVERROR_PATCHWELCOME;
 505                     }
 506                     if (!blocksize || blocksize > MAX_BLOCKSIZE) {
 507                         av_log(avctx, AV_LOG_ERROR, "invalid or unsupported "
 508                                "block size: %d\n", blocksize);
 509                         return AVERROR(EINVAL);
 510                     }
 511                     s->blocksize = blocksize;
 512                     break;
 513                 }
 514                 case FN_QUIT:
 515                     s->got_quit_command = 1;
 516                     break;
 517             }
 518             if (cmd == FN_BLOCKSIZE || cmd == FN_QUIT) {
 519                 *got_frame_ptr = 0;
 520                 break;
 521             }
 522         } else {
 523             /* process audio command */
 524             int residual_size = 0;
 525             int channel = s->cur_chan;
 526             int32_t coffset;
 527
 528             /* get Rice code for residual decoding */
 529             if (cmd != FN_ZERO) {
 530                 residual_size = get_ur_golomb_shorten(&s->gb, ENERGYSIZE);
 531                 /* This is a hack as version 0 differed in the definition
 532                  * of get_sr_golomb_shorten(). */
 533                 if (s->version == 0)
 534                     residual_size--;
 535             }
 536
 537             /* calculate sample offset using means from previous blocks */
 538             if (s->nmean == 0)
 539                 coffset = s->offset[channel][0];
 540             else {
 541                 int32_t sum = (s->version < 2) ? 0 : s->nmean / 2;
 542                 for (i=0; i<s->nmean; i++)
 543                     sum += s->offset[channel][i];
 544                 coffset = sum / s->nmean;
 545                 if (s->version >= 2)
 546                     coffset >>= FFMIN(1, s->bitshift);
 547             }
 548
 549             /* decode samples for this channel */
 550             if (cmd == FN_ZERO) {
 551                 for (i=0; i<s->blocksize; i++)
 552                     s->decoded[channel][i] = 0;
 553             } else {
 554                 if ((ret = decode_subframe_lpc(s, cmd, channel, residual_size, coffset)) < 0)
 555                     return ret;
 556             }
 557
 558             /* update means with info from the current block */
 559             if (s->nmean > 0) {
 560                 int32_t sum = (s->version < 2) ? 0 : s->blocksize / 2;
 561                 for (i=0; i<s->blocksize; i++)
 562                     sum += s->decoded[channel][i];
 563
 564                 for (i=1; i<s->nmean; i++)
 565                     s->offset[channel][i-1] = s->offset[channel][i];
 566
 567                 if (s->version < 2)
 568                     s->offset[channel][s->nmean - 1] = sum / s->blocksize;
 569                 else
 570                     s->offset[channel][s->nmean - 1] = (sum / s->blocksize) << s->bitshift;
 571             }
 572
 573             /* copy wrap samples for use with next block */
 574             for (i=-s->nwrap; i<0; i++)
 575                 s->decoded[channel][i] = s->decoded[channel][i + s->blocksize];
 576
 577             /* shift samples to add in unused zero bits which were removed
 578                during encoding */
 579             fix_bitshift(s, s->decoded[channel]);
 580
 581             /* if this is the last channel in the block, output the samples */
 582             s->cur_chan++;
 583             if (s->cur_chan == s->channels) {
 584                 /* get output buffer */
 585                 s->frame.nb_samples = s->blocksize;
 586                 if ((ret = ff_get_buffer(avctx, &s->frame)) < 0) {
 587                     av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 588                     return ret;
 589                 }
 590                 /* interleave output */
 591                 output_buffer((int16_t **)s->frame.extended_data, s->channels,
 592                               s->blocksize, s->decoded);
 593
 594                 *got_frame_ptr   = 1;
 595                 *(AVFrame *)data = s->frame;
 596             }
 597         }
 598     }
 599     if (s->cur_chan < s->channels)
 600         *got_frame_ptr = 0;
 601
 602 finish_frame:
 603     s->bitindex = get_bits_count(&s->gb) - 8*((get_bits_count(&s->gb))/8);
 604     i= (get_bits_count(&s->gb))/8;
 605     if (i > buf_size) {
 606         av_log(s->avctx, AV_LOG_ERROR, "overread: %d\n", i - buf_size);
 607         s->bitstream_size=0;
 608         s->bitstream_index=0;
 609         return -1;
 610     }
 611     if (s->bitstream_size) {
 612         s->bitstream_index += i;
 613         s->bitstream_size  -= i;
 614         return input_buf_size;
 615     } else
 616         return i;
 617 }
 618
 619 static av_cold int shorten_decode_close(AVCodecContext *avctx)
 620 {
 621     ShortenContext *s = avctx->priv_data;
 622     int i;
 623
 624     for (i = 0; i < s->channels; i++) {
 625         s->decoded[i] = NULL;
 626         av_freep(&s->decoded_base[i]);
 627         av_freep(&s->offset[i]);
 628     }
 629     av_freep(&s->bitstream);
 630     av_freep(&s->coeffs);
 631
 632     return 0;
 633 }
 634
 635 AVCodec ff_shorten_decoder = {
 636     .name           = "shorten",
 637     .type           = AVMEDIA_TYPE_AUDIO,
 638     .id             = AV_CODEC_ID_SHORTEN,
 639     .priv_data_size = sizeof(ShortenContext),
 640     .init           = shorten_decode_init,
 641     .close          = shorten_decode_close,
 642     .decode         = shorten_decode_frame,
 643     .capabilities   = CODEC_CAP_DELAY | CODEC_CAP_DR1,
 644     .long_name      = NULL_IF_CONFIG_SMALL("Shorten"),
 645     .sample_fmts    = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S16P,
 646                                                       AV_SAMPLE_FMT_NONE },
 647 };