libavformat/options.c

   1 /*
   2  * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
   3  *
   4  * This file is part of FFmpeg.
   5  *
   6  * FFmpeg is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * FFmpeg is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with FFmpeg; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20 #include "avformat.h"
  21 #include "avformat_internal.h"
  22 #include "avio_internal.h"
  23 #include "demux.h"
  24 #include "internal.h"
  25
  26 #include "libavcodec/avcodec.h"
  27 #include "libavcodec/codec_par.h"
  28
  29 #include "libavutil/avassert.h"
  30 #include "libavutil/iamf.h"
  31 #include "libavutil/internal.h"
  32 #include "libavutil/intmath.h"
  33 #include "libavutil/mem.h"
  34 #include "libavutil/opt.h"
  35
  36 /**
  37  * @file
  38  * Options definition for AVFormatContext.
  39  */
  40
  41 FF_DISABLE_DEPRECATION_WARNINGS
  42 #include "options_table.h"
  43 FF_ENABLE_DEPRECATION_WARNINGS
  44
  45 static const char* format_to_name(void* ptr)
  46 {
  47     AVFormatContext* fc = (AVFormatContext*) ptr;
  48     if(fc->iformat) return fc->iformat->name;
  49     else if(fc->oformat) return fc->oformat->name;
  50     else return fc->av_class->class_name;
  51 }
  52
  53 static void *format_child_next(void *obj, void *prev)
  54 {
  55     AVFormatContext *s = obj;
  56     if (!prev && s->priv_data &&
  57         ((s->iformat && s->iformat->priv_class) ||
  58           s->oformat && s->oformat->priv_class))
  59         return s->priv_data;
  60     if (s->pb && s->pb->av_class && prev != s->pb)
  61         return s->pb;
  62     return NULL;
  63 }
  64
  65 enum {
  66     CHILD_CLASS_ITER_AVIO = 0,
  67     CHILD_CLASS_ITER_MUX,
  68     CHILD_CLASS_ITER_DEMUX,
  69     CHILD_CLASS_ITER_DONE,
  70
  71 };
  72
  73 #define ITER_STATE_SHIFT 16
  74
  75 static const AVClass *format_child_class_iterate(void **iter)
  76 {
  77     // we use the low 16 bits of iter as the value to be passed to
  78     // av_(de)muxer_iterate()
  79     void *val = (void*)(((uintptr_t)*iter) & ((1 << ITER_STATE_SHIFT) - 1));
  80     unsigned int state = ((uintptr_t)*iter) >> ITER_STATE_SHIFT;
  81     const AVClass *ret = NULL;
  82
  83     if (state == CHILD_CLASS_ITER_AVIO) {
  84         ret = &ff_avio_class;
  85         state++;
  86         goto finish;
  87     }
  88
  89     if (state == CHILD_CLASS_ITER_MUX) {
  90         const AVOutputFormat *ofmt;
  91
  92         while ((ofmt = av_muxer_iterate(&val))) {
  93             ret = ofmt->priv_class;
  94             if (ret)
  95                 goto finish;
  96         }
  97
  98         val = NULL;
  99         state++;
 100     }
 101
 102     if (state == CHILD_CLASS_ITER_DEMUX) {
 103         const AVInputFormat *ifmt;
 104
 105         while ((ifmt = av_demuxer_iterate(&val))) {
 106             ret = ifmt->priv_class;
 107             if (ret)
 108                 goto finish;
 109         }
 110         val = NULL;
 111         state++;
 112     }
 113
 114 finish:
 115     // make sure none av_(de)muxer_iterate does not set the high bits of val
 116     av_assert0(!((uintptr_t)val >> ITER_STATE_SHIFT));
 117     *iter = (void*)((uintptr_t)val | (state << ITER_STATE_SHIFT));
 118     return ret;
 119 }
 120
 121 static AVClassCategory get_category(void *ptr)
 122 {
 123     AVFormatContext* s = ptr;
 124     if(s->iformat) return AV_CLASS_CATEGORY_DEMUXER;
 125     else           return AV_CLASS_CATEGORY_MUXER;
 126 }
 127
 128 static const AVClass av_format_context_class = {
 129     .class_name     = "AVFormatContext",
 130     .item_name      = format_to_name,
 131     .option         = avformat_options,
 132     .version        = LIBAVUTIL_VERSION_INT,
 133     .child_next     = format_child_next,
 134     .child_class_iterate = format_child_class_iterate,
 135     .category       = AV_CLASS_CATEGORY_MUXER,
 136     .get_category   = get_category,
 137 };
 138
 139 static int io_open_default(AVFormatContext *s, AVIOContext **pb,
 140                            const char *url, int flags, AVDictionary **options)
 141 {
 142     int loglevel;
 143
 144     if (!strcmp(url, s->url) ||
 145         s->iformat && !strcmp(s->iformat->name, "image2") ||
 146         s->oformat && !strcmp(s->oformat->name, "image2")
 147     ) {
 148         loglevel = AV_LOG_DEBUG;
 149     } else
 150         loglevel = AV_LOG_INFO;
 151
 152     av_log(s, loglevel, "Opening \'%s\' for %s\n", url, flags & AVIO_FLAG_WRITE ? "writing" : "reading");
 153
 154     return ffio_open_whitelist(pb, url, flags, &s->interrupt_callback, options, s->protocol_whitelist, s->protocol_blacklist);
 155 }
 156
 157 static int io_close2_default(AVFormatContext *s, AVIOContext *pb)
 158 {
 159     return avio_close(pb);
 160 }
 161
 162 AVFormatContext *avformat_alloc_context(void)
 163 {
 164     FormatContextInternal *fci;
 165     FFFormatContext *si;
 166     AVFormatContext *s;
 167
 168     fci = av_mallocz(sizeof(*fci));
 169     if (!fci)
 170         return NULL;
 171
 172     si = &fci->fc;
 173     s = &si->pub;
 174     s->av_class = &av_format_context_class;
 175     s->io_open  = io_open_default;
 176     s->io_close2= io_close2_default;
 177
 178     av_opt_set_defaults(s);
 179
 180     si->pkt = av_packet_alloc();
 181     si->parse_pkt = av_packet_alloc();
 182     if (!si->pkt || !si->parse_pkt) {
 183         avformat_free_context(s);
 184         return NULL;
 185     }
 186
 187     return s;
 188 }
 189
 190 const AVClass *avformat_get_class(void)
 191 {
 192     return &av_format_context_class;
 193 }
 194
 195 #define DISPOSITION_OPT(ctx)                                                                                                        \
 196     { "disposition", NULL, offsetof(ctx, disposition), AV_OPT_TYPE_FLAGS, { .i64 = 0 },                                             \
 197         .flags = AV_OPT_FLAG_ENCODING_PARAM, .unit = "disposition" },                                                               \
 198         { "default",            .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_DEFAULT           },    .unit = "disposition" }, \
 199         { "dub",                .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_DUB               },    .unit = "disposition" }, \
 200         { "original",           .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_ORIGINAL          },    .unit = "disposition" }, \
 201         { "comment",            .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_COMMENT           },    .unit = "disposition" }, \
 202         { "lyrics",             .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_LYRICS            },    .unit = "disposition" }, \
 203         { "karaoke",            .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_KARAOKE           },    .unit = "disposition" }, \
 204         { "forced",             .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_FORCED            },    .unit = "disposition" }, \
 205         { "hearing_impaired",   .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_HEARING_IMPAIRED  },    .unit = "disposition" }, \
 206         { "visual_impaired",    .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_VISUAL_IMPAIRED   },    .unit = "disposition" }, \
 207         { "clean_effects",      .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_CLEAN_EFFECTS     },    .unit = "disposition" }, \
 208         { "attached_pic",       .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_ATTACHED_PIC      },    .unit = "disposition" }, \
 209         { "timed_thumbnails",   .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_TIMED_THUMBNAILS  },    .unit = "disposition" }, \
 210         { "non_diegetic",       .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_NON_DIEGETIC      },    .unit = "disposition" }, \
 211         { "captions",           .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_CAPTIONS          },    .unit = "disposition" }, \
 212         { "descriptions",       .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_DESCRIPTIONS      },    .unit = "disposition" }, \
 213         { "metadata",           .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_METADATA          },    .unit = "disposition" }, \
 214         { "dependent",          .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_DEPENDENT         },    .unit = "disposition" }, \
 215         { "still_image",        .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_STILL_IMAGE       },    .unit = "disposition" }, \
 216         { "multilayer",         .type = AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_MULTILAYER        },    .unit = "disposition" }
 217
 218 static const AVOption stream_options[] = {
 219     DISPOSITION_OPT(AVStream),
 220     { "discard", NULL, offsetof(AVStream, discard), AV_OPT_TYPE_INT, { .i64 = AVDISCARD_DEFAULT }, INT_MIN, INT_MAX,
 221         .flags = AV_OPT_FLAG_DECODING_PARAM, .unit = "avdiscard" },
 222         { "none",               .type = AV_OPT_TYPE_CONST, {.i64 = AVDISCARD_NONE     }, .unit = "avdiscard" },
 223         { "default",            .type = AV_OPT_TYPE_CONST, {.i64 = AVDISCARD_DEFAULT  }, .unit = "avdiscard" },
 224         { "noref",              .type = AV_OPT_TYPE_CONST, {.i64 = AVDISCARD_NONREF   }, .unit = "avdiscard" },
 225         { "bidir",              .type = AV_OPT_TYPE_CONST, {.i64 = AVDISCARD_BIDIR    }, .unit = "avdiscard" },
 226         { "nointra",            .type = AV_OPT_TYPE_CONST, {.i64 = AVDISCARD_NONINTRA }, .unit = "avdiscard" },
 227         { "nokey",              .type = AV_OPT_TYPE_CONST, {.i64 = AVDISCARD_NONKEY   }, .unit = "avdiscard" },
 228         { "all",                .type = AV_OPT_TYPE_CONST, {.i64 = AVDISCARD_ALL      }, .unit = "avdiscard" },
 229     { NULL }
 230 };
 231
 232 static const AVClass stream_class = {
 233     .class_name     = "AVStream",
 234     .item_name      = av_default_item_name,
 235     .version        = LIBAVUTIL_VERSION_INT,
 236     .option         = stream_options,
 237 };
 238
 239 const AVClass *av_stream_get_class(void)
 240 {
 241     return &stream_class;
 242 }
 243
 244 AVStream *avformat_new_stream(AVFormatContext *s, const AVCodec *c)
 245 {
 246     FFStream *sti;
 247     AVStream *st;
 248     AVStream **streams;
 249
 250     if (s->nb_streams >= s->max_streams) {
 251         av_log(s, AV_LOG_ERROR, "Number of streams exceeds max_streams parameter"
 252                " (%d), see the documentation if you wish to increase it\n",
 253                s->max_streams);
 254         return NULL;
 255     }
 256     streams = av_realloc_array(s->streams, s->nb_streams + 1, sizeof(*streams));
 257     if (!streams)
 258         return NULL;
 259     s->streams = streams;
 260
 261     sti = av_mallocz(sizeof(*sti));
 262     if (!sti)
 263         return NULL;
 264     st = &sti->pub;
 265
 266     st->av_class = &stream_class;
 267     st->codecpar = avcodec_parameters_alloc();
 268     if (!st->codecpar)
 269         goto fail;
 270
 271     sti->fmtctx = s;
 272
 273     if (s->iformat) {
 274         sti->avctx = avcodec_alloc_context3(NULL);
 275         if (!sti->avctx)
 276             goto fail;
 277
 278         sti->info = av_mallocz(sizeof(*sti->info));
 279         if (!sti->info)
 280             goto fail;
 281
 282 #if FF_API_R_FRAME_RATE
 283         sti->info->last_dts      = AV_NOPTS_VALUE;
 284 #endif
 285         sti->info->fps_first_dts = AV_NOPTS_VALUE;
 286         sti->info->fps_last_dts  = AV_NOPTS_VALUE;
 287
 288         /* default pts setting is MPEG-like */
 289         avpriv_set_pts_info(st, 33, 1, 90000);
 290         /* we set the current DTS to 0 so that formats without any timestamps
 291          * but durations get some timestamps, formats with some unknown
 292          * timestamps have their first few packets buffered and the
 293          * timestamps corrected before they are returned to the user */
 294         sti->cur_dts = RELATIVE_TS_BASE;
 295     } else {
 296         sti->cur_dts = AV_NOPTS_VALUE;
 297     }
 298
 299     st->index      = s->nb_streams;
 300     st->start_time = AV_NOPTS_VALUE;
 301     st->duration   = AV_NOPTS_VALUE;
 302     sti->first_dts     = AV_NOPTS_VALUE;
 303     sti->probe_packets = s->max_probe_packets;
 304     sti->pts_wrap_reference = AV_NOPTS_VALUE;
 305     sti->pts_wrap_behavior  = AV_PTS_WRAP_IGNORE;
 306
 307     sti->last_IP_pts = AV_NOPTS_VALUE;
 308     sti->last_dts_for_order_check = AV_NOPTS_VALUE;
 309     for (int i = 0; i < MAX_REORDER_DELAY + 1; i++)
 310         sti->pts_buffer[i] = AV_NOPTS_VALUE;
 311
 312     st->sample_aspect_ratio = (AVRational) { 0, 1 };
 313 #if FF_API_INTERNAL_TIMING
 314     sti->transferred_mux_tb = (AVRational) { 0, 1 };;
 315 #endif
 316
 317     sti->need_context_update = 1;
 318
 319     s->streams[s->nb_streams++] = st;
 320     return st;
 321 fail:
 322     ff_free_stream(&st);
 323     return NULL;
 324 }
 325
 326 #define FLAGS AV_OPT_FLAG_ENCODING_PARAM | AV_OPT_FLAG_VIDEO_PARAM
 327 #define OFFSET(x) offsetof(AVStreamGroupTileGrid, x)
 328 static const AVOption tile_grid_options[] = {
 329     { "grid_size", "size of the output canvas", OFFSET(coded_width),
 330         AV_OPT_TYPE_IMAGE_SIZE, { .str = NULL }, 0, INT_MAX, FLAGS },
 331     { "output_size", "size of valid pixels in output image meant for presentation", OFFSET(width),
 332         AV_OPT_TYPE_IMAGE_SIZE, { .str = NULL }, 0, INT_MAX, FLAGS },
 333     { "background_color", "set a background color for unused pixels",
 334         OFFSET(background), AV_OPT_TYPE_COLOR, { .str = "black"}, 0, 0, FLAGS },
 335     { "horizontal_offset", NULL, OFFSET(horizontal_offset), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, FLAGS },
 336     { "vertical_offset",   NULL, OFFSET(vertical_offset),   AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, FLAGS },
 337     { NULL },
 338 };
 339 #undef OFFSET
 340
 341 static const AVClass tile_grid_class = {
 342     .class_name = "AVStreamGroupTileGrid",
 343     .version    = LIBAVUTIL_VERSION_INT,
 344     .option     = tile_grid_options,
 345 };
 346
 347 #define OFFSET(x) offsetof(AVStreamGroupLCEVC, x)
 348 static const AVOption lcevc_options[] = {
 349     { "video_size", "size of video after LCEVC enhancement has been applied", OFFSET(width),
 350         AV_OPT_TYPE_IMAGE_SIZE, { .str = NULL }, 0, INT_MAX, FLAGS },
 351     { NULL },
 352 };
 353 #undef OFFSET
 354
 355 static const AVClass lcevc_class = {
 356     .class_name = "AVStreamGroupLCEVC",
 357     .version    = LIBAVUTIL_VERSION_INT,
 358     .option     = lcevc_options,
 359 };
 360
 361 static void *stream_group_child_next(void *obj, void *prev)
 362 {
 363     AVStreamGroup *stg = obj;
 364     if (!prev) {
 365         switch(stg->type) {
 366         case AV_STREAM_GROUP_PARAMS_IAMF_AUDIO_ELEMENT:
 367             return stg->params.iamf_audio_element;
 368         case AV_STREAM_GROUP_PARAMS_IAMF_MIX_PRESENTATION:
 369             return stg->params.iamf_mix_presentation;
 370         case AV_STREAM_GROUP_PARAMS_TILE_GRID:
 371             return stg->params.tile_grid;
 372         case AV_STREAM_GROUP_PARAMS_LCEVC:
 373             return stg->params.lcevc;
 374         default:
 375             break;
 376         }
 377     }
 378     return NULL;
 379 }
 380
 381 #undef FLAGS
 382
 383 static const AVClass *stream_group_child_iterate(void **opaque)
 384 {
 385     uintptr_t i = (uintptr_t)*opaque;
 386     const AVClass *ret = NULL;
 387
 388     switch(i) {
 389     case AV_STREAM_GROUP_PARAMS_NONE:
 390         i++;
 391     // fall-through
 392     case AV_STREAM_GROUP_PARAMS_IAMF_AUDIO_ELEMENT:
 393         ret = av_iamf_audio_element_get_class();
 394         break;
 395     case AV_STREAM_GROUP_PARAMS_IAMF_MIX_PRESENTATION:
 396         ret = av_iamf_mix_presentation_get_class();
 397         break;
 398     case AV_STREAM_GROUP_PARAMS_TILE_GRID:
 399         ret = &tile_grid_class;
 400         break;
 401     case AV_STREAM_GROUP_PARAMS_LCEVC:
 402         ret = &lcevc_class;
 403         break;
 404     default:
 405         break;
 406     }
 407
 408     if (ret)
 409         *opaque = (void*)(i + 1);
 410     return ret;
 411 }
 412
 413 static const AVOption stream_group_options[] = {
 414     DISPOSITION_OPT(AVStreamGroup),
 415     {"id", "Set group id", offsetof(AVStreamGroup, id), AV_OPT_TYPE_INT64, {.i64 = 0}, 0, INT64_MAX, AV_OPT_FLAG_ENCODING_PARAM },
 416     { NULL }
 417 };
 418
 419 static const AVClass stream_group_class = {
 420     .class_name     = "AVStreamGroup",
 421     .item_name      = av_default_item_name,
 422     .version        = LIBAVUTIL_VERSION_INT,
 423     .option         = stream_group_options,
 424     .child_next     = stream_group_child_next,
 425     .child_class_iterate = stream_group_child_iterate,
 426 };
 427
 428 const AVClass *av_stream_group_get_class(void)
 429 {
 430     return &stream_group_class;
 431 }
 432
 433 AVStreamGroup *avformat_stream_group_create(AVFormatContext *s,
 434                                             enum AVStreamGroupParamsType type,
 435                                             AVDictionary **options)
 436 {
 437     AVStreamGroup **stream_groups;
 438     AVStreamGroup *stg;
 439     FFStreamGroup *stgi;
 440
 441     stream_groups = av_realloc_array(s->stream_groups, s->nb_stream_groups + 1,
 442                                      sizeof(*stream_groups));
 443     if (!stream_groups)
 444         return NULL;
 445     s->stream_groups = stream_groups;
 446
 447     stgi = av_mallocz(sizeof(*stgi));
 448     if (!stgi)
 449         return NULL;
 450     stg = &stgi->pub;
 451
 452     stg->av_class = &stream_group_class;
 453     av_opt_set_defaults(stg);
 454     stg->type = type;
 455     switch (type) {
 456     case AV_STREAM_GROUP_PARAMS_IAMF_AUDIO_ELEMENT:
 457         stg->params.iamf_audio_element = av_iamf_audio_element_alloc();
 458         if (!stg->params.iamf_audio_element)
 459             goto fail;
 460         break;
 461     case AV_STREAM_GROUP_PARAMS_IAMF_MIX_PRESENTATION:
 462         stg->params.iamf_mix_presentation = av_iamf_mix_presentation_alloc();
 463         if (!stg->params.iamf_mix_presentation)
 464             goto fail;
 465         break;
 466     case AV_STREAM_GROUP_PARAMS_TILE_GRID:
 467         stg->params.tile_grid = av_mallocz(sizeof(*stg->params.tile_grid));
 468         if (!stg->params.tile_grid)
 469             goto fail;
 470         stg->params.tile_grid->av_class = &tile_grid_class;
 471         av_opt_set_defaults(stg->params.tile_grid);
 472         break;
 473     case AV_STREAM_GROUP_PARAMS_LCEVC:
 474         stg->params.lcevc = av_mallocz(sizeof(*stg->params.lcevc));
 475         if (!stg->params.lcevc)
 476             goto fail;
 477         stg->params.lcevc->av_class = &lcevc_class;
 478         av_opt_set_defaults(stg->params.lcevc);
 479         break;
 480     default:
 481         goto fail;
 482     }
 483
 484     if (options) {
 485         if (av_opt_set_dict2(stg, options, AV_OPT_SEARCH_CHILDREN))
 486             goto fail;
 487     }
 488
 489     stgi->fmtctx = s;
 490     stg->index   = s->nb_stream_groups;
 491
 492     s->stream_groups[s->nb_stream_groups++] = stg;
 493
 494     return stg;
 495 fail:
 496     ff_free_stream_group(&stg);
 497     return NULL;
 498 }
 499
 500 static int stream_group_add_stream(AVStreamGroup *stg, AVStream *st)
 501 {
 502     AVStream **streams = av_realloc_array(stg->streams, stg->nb_streams + 1,
 503                                           sizeof(*stg->streams));
 504     if (!streams)
 505         return AVERROR(ENOMEM);
 506
 507     stg->streams = streams;
 508     stg->streams[stg->nb_streams++] = st;
 509
 510     return 0;
 511 }
 512
 513 int avformat_stream_group_add_stream(AVStreamGroup *stg, AVStream *st)
 514 {
 515     const FFStreamGroup *stgi = cffstreamgroup(stg);
 516     const FFStream *sti = cffstream(st);
 517
 518     if (stgi->fmtctx != sti->fmtctx)
 519         return AVERROR(EINVAL);
 520
 521     for (int i = 0; i < stg->nb_streams; i++)
 522         if (stg->streams[i]->index == st->index)
 523             return AVERROR(EEXIST);
 524
 525     return stream_group_add_stream(stg, st);
 526 }
 527
 528 static int option_is_disposition(const AVOption *opt)
 529 {
 530     return opt->type == AV_OPT_TYPE_CONST &&
 531            opt->unit && !strcmp(opt->unit, "disposition");
 532 }
 533
 534 int av_disposition_from_string(const char *disp)
 535 {
 536     for (const AVOption *opt = stream_options; opt->name; opt++)
 537         if (option_is_disposition(opt) && !strcmp(disp, opt->name))
 538             return opt->default_val.i64;
 539     return AVERROR(EINVAL);
 540 }
 541
 542 const char *av_disposition_to_string(int disposition)
 543 {
 544     int val;
 545
 546     if (disposition <= 0)
 547         return NULL;
 548
 549     val = 1 << ff_ctz(disposition);
 550     for (const AVOption *opt = stream_options; opt->name; opt++)
 551         if (option_is_disposition(opt) && opt->default_val.i64 == val)
 552             return opt->name;
 553
 554     return NULL;
 555 }