libavutil/hwcontext.c

   1 /*
   2  * This file is part of Libav.
   3  *
   4  * Libav is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * Libav is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with Libav; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17  */
  18
  19 #include "config.h"
  20
  21 #include "buffer.h"
  22 #include "common.h"
  23 #include "hwcontext.h"
  24 #include "hwcontext_internal.h"
  25 #include "imgutils.h"
  26 #include "log.h"
  27 #include "mem.h"
  28 #include "pixdesc.h"
  29 #include "pixfmt.h"
  30
  31 static const HWContextType * const hw_table[] = {
  32 #if CONFIG_CUDA
  33     &ff_hwcontext_type_cuda,
  34 #endif
  35 #if CONFIG_DXVA2
  36     &ff_hwcontext_type_dxva2,
  37 #endif
  38 #if CONFIG_LIBMFX
  39     &ff_hwcontext_type_qsv,
  40 #endif
  41 #if CONFIG_VAAPI
  42     &ff_hwcontext_type_vaapi,
  43 #endif
  44 #if CONFIG_VDPAU
  45     &ff_hwcontext_type_vdpau,
  46 #endif
  47     NULL,
  48 };
  49
  50 const char *hw_type_names[] = {
  51     [AV_HWDEVICE_TYPE_CUDA]   = "cuda",
  52     [AV_HWDEVICE_TYPE_DXVA2]  = "dxva2",
  53     [AV_HWDEVICE_TYPE_QSV]    = "qsv",
  54     [AV_HWDEVICE_TYPE_VAAPI]  = "vaapi",
  55     [AV_HWDEVICE_TYPE_VDPAU]  = "vdpau",
  56 };
  57
  58 enum AVHWDeviceType av_hwdevice_find_type_by_name(const char *name)
  59 {
  60     int type;
  61     for (type = 0; type < FF_ARRAY_ELEMS(hw_type_names); type++) {
  62         if (hw_type_names[type] && !strcmp(hw_type_names[type], name))
  63             return type;
  64     }
  65     return AV_HWDEVICE_TYPE_NONE;
  66 }
  67
  68 const char *av_hwdevice_get_type_name(enum AVHWDeviceType type)
  69 {
  70     if (type >= 0 && type < FF_ARRAY_ELEMS(hw_type_names))
  71         return hw_type_names[type];
  72     else
  73         return NULL;
  74 }
  75
  76 enum AVHWDeviceType av_hwdevice_iterate_types(enum AVHWDeviceType prev)
  77 {
  78     enum AVHWDeviceType next;
  79     int i, set = 0;
  80     for (i = 0; hw_table[i]; i++) {
  81         if (prev != AV_HWDEVICE_TYPE_NONE && hw_table[i]->type <= prev)
  82             continue;
  83         if (!set || hw_table[i]->type < next) {
  84             next = hw_table[i]->type;
  85             set = 1;
  86         }
  87     }
  88     return set ? next : AV_HWDEVICE_TYPE_NONE;
  89 }
  90
  91 static const AVClass hwdevice_ctx_class = {
  92     .class_name = "AVHWDeviceContext",
  93     .item_name  = av_default_item_name,
  94     .version    = LIBAVUTIL_VERSION_INT,
  95 };
  96
  97 static void hwdevice_ctx_free(void *opaque, uint8_t *data)
  98 {
  99     AVHWDeviceContext *ctx = (AVHWDeviceContext*)data;
 100
 101     /* uninit might still want access the hw context and the user
 102      * free() callback might destroy it, so uninit has to be called first */
 103     if (ctx->internal->hw_type->device_uninit)
 104         ctx->internal->hw_type->device_uninit(ctx);
 105
 106     if (ctx->free)
 107         ctx->free(ctx);
 108
 109     av_buffer_unref(&ctx->internal->source_device);
 110
 111     av_freep(&ctx->hwctx);
 112     av_freep(&ctx->internal->priv);
 113     av_freep(&ctx->internal);
 114     av_freep(&ctx);
 115 }
 116
 117 AVBufferRef *av_hwdevice_ctx_alloc(enum AVHWDeviceType type)
 118 {
 119     AVHWDeviceContext *ctx;
 120     AVBufferRef *buf;
 121     const HWContextType *hw_type = NULL;
 122     int i;
 123
 124     for (i = 0; hw_table[i]; i++) {
 125         if (hw_table[i]->type == type) {
 126             hw_type = hw_table[i];
 127             break;
 128         }
 129     }
 130     if (!hw_type)
 131         return NULL;
 132
 133     ctx = av_mallocz(sizeof(*ctx));
 134     if (!ctx)
 135         return NULL;
 136
 137     ctx->internal = av_mallocz(sizeof(*ctx->internal));
 138     if (!ctx->internal)
 139         goto fail;
 140
 141     if (hw_type->device_priv_size) {
 142         ctx->internal->priv = av_mallocz(hw_type->device_priv_size);
 143         if (!ctx->internal->priv)
 144             goto fail;
 145     }
 146
 147     if (hw_type->device_hwctx_size) {
 148         ctx->hwctx = av_mallocz(hw_type->device_hwctx_size);
 149         if (!ctx->hwctx)
 150             goto fail;
 151     }
 152
 153     buf = av_buffer_create((uint8_t*)ctx, sizeof(*ctx),
 154                            hwdevice_ctx_free, NULL,
 155                            AV_BUFFER_FLAG_READONLY);
 156     if (!buf)
 157         goto fail;
 158
 159     ctx->type     = type;
 160     ctx->av_class = &hwdevice_ctx_class;
 161
 162     ctx->internal->hw_type = hw_type;
 163
 164     return buf;
 165
 166 fail:
 167     if (ctx->internal)
 168         av_freep(&ctx->internal->priv);
 169     av_freep(&ctx->internal);
 170     av_freep(&ctx->hwctx);
 171     av_freep(&ctx);
 172     return NULL;
 173 }
 174
 175 int av_hwdevice_ctx_init(AVBufferRef *ref)
 176 {
 177     AVHWDeviceContext *ctx = (AVHWDeviceContext*)ref->data;
 178     int ret;
 179
 180     if (ctx->internal->hw_type->device_init) {
 181         ret = ctx->internal->hw_type->device_init(ctx);
 182         if (ret < 0)
 183             goto fail;
 184     }
 185
 186     return 0;
 187 fail:
 188     if (ctx->internal->hw_type->device_uninit)
 189         ctx->internal->hw_type->device_uninit(ctx);
 190     return ret;
 191 }
 192
 193 static const AVClass hwframe_ctx_class = {
 194     .class_name = "AVHWFramesContext",
 195     .item_name  = av_default_item_name,
 196     .version    = LIBAVUTIL_VERSION_INT,
 197 };
 198
 199 static void hwframe_ctx_free(void *opaque, uint8_t *data)
 200 {
 201     AVHWFramesContext *ctx = (AVHWFramesContext*)data;
 202
 203     if (ctx->internal->source_frames) {
 204         av_buffer_unref(&ctx->internal->source_frames);
 205
 206     } else {
 207         if (ctx->internal->pool_internal)
 208             av_buffer_pool_uninit(&ctx->internal->pool_internal);
 209
 210         if (ctx->internal->hw_type->frames_uninit)
 211             ctx->internal->hw_type->frames_uninit(ctx);
 212
 213         if (ctx->free)
 214             ctx->free(ctx);
 215     }
 216
 217     av_buffer_unref(&ctx->device_ref);
 218
 219     av_freep(&ctx->hwctx);
 220     av_freep(&ctx->internal->priv);
 221     av_freep(&ctx->internal);
 222     av_freep(&ctx);
 223 }
 224
 225 AVBufferRef *av_hwframe_ctx_alloc(AVBufferRef *device_ref_in)
 226 {
 227     AVHWDeviceContext *device_ctx = (AVHWDeviceContext*)device_ref_in->data;
 228     const HWContextType  *hw_type = device_ctx->internal->hw_type;
 229     AVHWFramesContext *ctx;
 230     AVBufferRef *buf, *device_ref = NULL;;
 231
 232     ctx = av_mallocz(sizeof(*ctx));
 233     if (!ctx)
 234         return NULL;
 235
 236     ctx->internal = av_mallocz(sizeof(*ctx->internal));
 237     if (!ctx->internal)
 238         goto fail;
 239
 240     if (hw_type->frames_priv_size) {
 241         ctx->internal->priv = av_mallocz(hw_type->frames_priv_size);
 242         if (!ctx->internal->priv)
 243             goto fail;
 244     }
 245
 246     if (hw_type->frames_hwctx_size) {
 247         ctx->hwctx = av_mallocz(hw_type->frames_hwctx_size);
 248         if (!ctx->hwctx)
 249             goto fail;
 250     }
 251
 252     device_ref = av_buffer_ref(device_ref_in);
 253     if (!device_ref)
 254         goto fail;
 255
 256     buf = av_buffer_create((uint8_t*)ctx, sizeof(*ctx),
 257                            hwframe_ctx_free, NULL,
 258                            AV_BUFFER_FLAG_READONLY);
 259     if (!buf)
 260         goto fail;
 261
 262     ctx->av_class   = &hwframe_ctx_class;
 263     ctx->device_ref = device_ref;
 264     ctx->device_ctx = device_ctx;
 265     ctx->format     = AV_PIX_FMT_NONE;
 266     ctx->sw_format  = AV_PIX_FMT_NONE;
 267
 268     ctx->internal->hw_type = hw_type;
 269
 270     return buf;
 271
 272 fail:
 273     if (device_ref)
 274         av_buffer_unref(&device_ref);
 275     if (ctx->internal)
 276         av_freep(&ctx->internal->priv);
 277     av_freep(&ctx->internal);
 278     av_freep(&ctx->hwctx);
 279     av_freep(&ctx);
 280     return NULL;
 281 }
 282
 283 static int hwframe_pool_prealloc(AVBufferRef *ref)
 284 {
 285     AVHWFramesContext *ctx = (AVHWFramesContext*)ref->data;
 286     AVFrame **frames;
 287     int i, ret = 0;
 288
 289     frames = av_mallocz_array(ctx->initial_pool_size, sizeof(*frames));
 290     if (!frames)
 291         return AVERROR(ENOMEM);
 292
 293     for (i = 0; i < ctx->initial_pool_size; i++) {
 294         frames[i] = av_frame_alloc();
 295         if (!frames[i])
 296             goto fail;
 297
 298         ret = av_hwframe_get_buffer(ref, frames[i], 0);
 299         if (ret < 0)
 300             goto fail;
 301     }
 302
 303 fail:
 304     for (i = 0; i < ctx->initial_pool_size; i++)
 305         av_frame_free(&frames[i]);
 306     av_freep(&frames);
 307
 308     return ret;
 309 }
 310
 311 int av_hwframe_ctx_init(AVBufferRef *ref)
 312 {
 313     AVHWFramesContext *ctx = (AVHWFramesContext*)ref->data;
 314     const enum AVPixelFormat *pix_fmt;
 315     int ret;
 316
 317     if (ctx->internal->source_frames) {
 318         /* A derived frame context is already initialised. */
 319         return 0;
 320     }
 321
 322     /* validate the pixel format */
 323     for (pix_fmt = ctx->internal->hw_type->pix_fmts; *pix_fmt != AV_PIX_FMT_NONE; pix_fmt++) {
 324         if (*pix_fmt == ctx->format)
 325             break;
 326     }
 327     if (*pix_fmt == AV_PIX_FMT_NONE) {
 328         av_log(ctx, AV_LOG_ERROR,
 329                "The hardware pixel format '%s' is not supported by the device type '%s'\n",
 330                av_get_pix_fmt_name(ctx->format), ctx->internal->hw_type->name);
 331         return AVERROR(ENOSYS);
 332     }
 333
 334     /* validate the dimensions */
 335     ret = av_image_check_size(ctx->width, ctx->height, 0, ctx);
 336     if (ret < 0)
 337         return ret;
 338
 339     /* format-specific init */
 340     if (ctx->internal->hw_type->frames_init) {
 341         ret = ctx->internal->hw_type->frames_init(ctx);
 342         if (ret < 0)
 343             goto fail;
 344     }
 345
 346     if (ctx->internal->pool_internal && !ctx->pool)
 347         ctx->pool = ctx->internal->pool_internal;
 348
 349     /* preallocate the frames in the pool, if requested */
 350     if (ctx->initial_pool_size > 0) {
 351         ret = hwframe_pool_prealloc(ref);
 352         if (ret < 0)
 353             goto fail;
 354     }
 355
 356     return 0;
 357 fail:
 358     if (ctx->internal->hw_type->frames_uninit)
 359         ctx->internal->hw_type->frames_uninit(ctx);
 360     return ret;
 361 }
 362
 363 int av_hwframe_transfer_get_formats(AVBufferRef *hwframe_ref,
 364                                     enum AVHWFrameTransferDirection dir,
 365                                     enum AVPixelFormat **formats, int flags)
 366 {
 367     AVHWFramesContext *ctx = (AVHWFramesContext*)hwframe_ref->data;
 368
 369     if (!ctx->internal->hw_type->transfer_get_formats)
 370         return AVERROR(ENOSYS);
 371
 372     return ctx->internal->hw_type->transfer_get_formats(ctx, dir, formats);
 373 }
 374
 375 static int transfer_data_alloc(AVFrame *dst, const AVFrame *src, int flags)
 376 {
 377     AVHWFramesContext *ctx = (AVHWFramesContext*)src->hw_frames_ctx->data;
 378     AVFrame *frame_tmp;
 379     int ret = 0;
 380
 381     frame_tmp = av_frame_alloc();
 382     if (!frame_tmp)
 383         return AVERROR(ENOMEM);
 384
 385     /* if the format is set, use that
 386      * otherwise pick the first supported one */
 387     if (dst->format >= 0) {
 388         frame_tmp->format = dst->format;
 389     } else {
 390         enum AVPixelFormat *formats;
 391
 392         ret = av_hwframe_transfer_get_formats(src->hw_frames_ctx,
 393                                               AV_HWFRAME_TRANSFER_DIRECTION_FROM,
 394                                               &formats, 0);
 395         if (ret < 0)
 396             goto fail;
 397         frame_tmp->format = formats[0];
 398         av_freep(&formats);
 399     }
 400     frame_tmp->width  = ctx->width;
 401     frame_tmp->height = ctx->height;
 402
 403     ret = av_frame_get_buffer(frame_tmp, 32);
 404     if (ret < 0)
 405         goto fail;
 406
 407     ret = av_hwframe_transfer_data(frame_tmp, src, flags);
 408     if (ret < 0)
 409         goto fail;
 410
 411     frame_tmp->width  = src->width;
 412     frame_tmp->height = src->height;
 413
 414     av_frame_move_ref(dst, frame_tmp);
 415
 416 fail:
 417     av_frame_free(&frame_tmp);
 418     return ret;
 419 }
 420
 421 int av_hwframe_transfer_data(AVFrame *dst, const AVFrame *src, int flags)
 422 {
 423     AVHWFramesContext *ctx;
 424     int ret;
 425
 426     if (!dst->buf[0])
 427         return transfer_data_alloc(dst, src, flags);
 428
 429     if (src->hw_frames_ctx) {
 430         ctx = (AVHWFramesContext*)src->hw_frames_ctx->data;
 431
 432         ret = ctx->internal->hw_type->transfer_data_from(ctx, dst, src);
 433         if (ret < 0)
 434             return ret;
 435     } else if (dst->hw_frames_ctx) {
 436         ctx = (AVHWFramesContext*)dst->hw_frames_ctx->data;
 437
 438         ret = ctx->internal->hw_type->transfer_data_to(ctx, dst, src);
 439         if (ret < 0)
 440             return ret;
 441     } else
 442         return AVERROR(ENOSYS);
 443
 444     return 0;
 445 }
 446
 447 int av_hwframe_get_buffer(AVBufferRef *hwframe_ref, AVFrame *frame, int flags)
 448 {
 449     AVHWFramesContext *ctx = (AVHWFramesContext*)hwframe_ref->data;
 450     int ret;
 451
 452     if (ctx->internal->source_frames) {
 453         // This is a derived frame context, so we allocate in the source
 454         // and map the frame immediately.
 455         AVFrame *src_frame;
 456
 457         src_frame = av_frame_alloc();
 458         if (!src_frame)
 459             return AVERROR(ENOMEM);
 460
 461         ret = av_hwframe_get_buffer(ctx->internal->source_frames,
 462                                     src_frame, 0);
 463         if (ret < 0)
 464             return ret;
 465
 466         ret = av_hwframe_map(frame, src_frame, 0);
 467         if (ret) {
 468             av_log(ctx, AV_LOG_ERROR, "Failed to map frame into derived "
 469                    "frame context: %d.\n", ret);
 470             av_frame_free(&src_frame);
 471             return ret;
 472         }
 473
 474         // Free the source frame immediately - the mapped frame still
 475         // contains a reference to it.
 476         av_frame_free(&src_frame);
 477
 478         return 0;
 479     }
 480
 481     if (!ctx->internal->hw_type->frames_get_buffer)
 482         return AVERROR(ENOSYS);
 483
 484     if (!ctx->pool)
 485         return AVERROR(EINVAL);
 486
 487     frame->hw_frames_ctx = av_buffer_ref(hwframe_ref);
 488     if (!frame->hw_frames_ctx)
 489         return AVERROR(ENOMEM);
 490
 491     ret = ctx->internal->hw_type->frames_get_buffer(ctx, frame);
 492     if (ret < 0) {
 493         av_buffer_unref(&frame->hw_frames_ctx);
 494         return ret;
 495     }
 496
 497     return 0;
 498 }
 499
 500 void *av_hwdevice_hwconfig_alloc(AVBufferRef *ref)
 501 {
 502     AVHWDeviceContext *ctx = (AVHWDeviceContext*)ref->data;
 503     const HWContextType  *hw_type = ctx->internal->hw_type;
 504
 505     if (hw_type->device_hwconfig_size == 0)
 506         return NULL;
 507
 508     return av_mallocz(hw_type->device_hwconfig_size);
 509 }
 510
 511 AVHWFramesConstraints *av_hwdevice_get_hwframe_constraints(AVBufferRef *ref,
 512                                                            const void *hwconfig)
 513 {
 514     AVHWDeviceContext *ctx = (AVHWDeviceContext*)ref->data;
 515     const HWContextType  *hw_type = ctx->internal->hw_type;
 516     AVHWFramesConstraints *constraints;
 517
 518     if (!hw_type->frames_get_constraints)
 519         return NULL;
 520
 521     constraints = av_mallocz(sizeof(*constraints));
 522     if (!constraints)
 523         return NULL;
 524
 525     constraints->min_width = constraints->min_height = 0;
 526     constraints->max_width = constraints->max_height = INT_MAX;
 527
 528     if (hw_type->frames_get_constraints(ctx, hwconfig, constraints) >= 0) {
 529         return constraints;
 530     } else {
 531         av_hwframe_constraints_free(&constraints);
 532         return NULL;
 533     }
 534 }
 535
 536 void av_hwframe_constraints_free(AVHWFramesConstraints **constraints)
 537 {
 538     if (*constraints) {
 539         av_freep(&(*constraints)->valid_hw_formats);
 540         av_freep(&(*constraints)->valid_sw_formats);
 541     }
 542     av_freep(constraints);
 543 }
 544
 545 int av_hwdevice_ctx_create(AVBufferRef **pdevice_ref, enum AVHWDeviceType type,
 546                            const char *device, AVDictionary *opts, int flags)
 547 {
 548     AVBufferRef *device_ref = NULL;
 549     AVHWDeviceContext *device_ctx;
 550     int ret = 0;
 551
 552     device_ref = av_hwdevice_ctx_alloc(type);
 553     if (!device_ref) {
 554         ret = AVERROR(ENOMEM);
 555         goto fail;
 556     }
 557     device_ctx = (AVHWDeviceContext*)device_ref->data;
 558
 559     if (!device_ctx->internal->hw_type->device_create) {
 560         ret = AVERROR(ENOSYS);
 561         goto fail;
 562     }
 563
 564     ret = device_ctx->internal->hw_type->device_create(device_ctx, device,
 565                                                        opts, flags);
 566     if (ret < 0)
 567         goto fail;
 568
 569     ret = av_hwdevice_ctx_init(device_ref);
 570     if (ret < 0)
 571         goto fail;
 572
 573     *pdevice_ref = device_ref;
 574     return 0;
 575 fail:
 576     av_buffer_unref(&device_ref);
 577     *pdevice_ref = NULL;
 578     return ret;
 579 }
 580
 581 int av_hwdevice_ctx_create_derived(AVBufferRef **dst_ref_ptr,
 582                                    enum AVHWDeviceType type,
 583                                    AVBufferRef *src_ref, int flags)
 584 {
 585     AVBufferRef *dst_ref = NULL, *tmp_ref;
 586     AVHWDeviceContext *dst_ctx, *tmp_ctx;
 587     int ret = 0;
 588
 589     tmp_ref = src_ref;
 590     while (tmp_ref) {
 591         tmp_ctx = (AVHWDeviceContext*)tmp_ref->data;
 592         if (tmp_ctx->type == type) {
 593             dst_ref = av_buffer_ref(tmp_ref);
 594             if (!dst_ref) {
 595                 ret = AVERROR(ENOMEM);
 596                 goto fail;
 597             }
 598             goto done;
 599         }
 600         tmp_ref = tmp_ctx->internal->source_device;
 601     }
 602
 603     dst_ref = av_hwdevice_ctx_alloc(type);
 604     if (!dst_ref) {
 605         ret = AVERROR(ENOMEM);
 606         goto fail;
 607     }
 608     dst_ctx = (AVHWDeviceContext*)dst_ref->data;
 609
 610     tmp_ref = src_ref;
 611     while (tmp_ref) {
 612         tmp_ctx = (AVHWDeviceContext*)tmp_ref->data;
 613         if (dst_ctx->internal->hw_type->device_derive) {
 614             ret = dst_ctx->internal->hw_type->device_derive(dst_ctx,
 615                                                             tmp_ctx,
 616                                                             flags);
 617             if (ret == 0) {
 618                 dst_ctx->internal->source_device = av_buffer_ref(src_ref);
 619                 if (!dst_ctx->internal->source_device) {
 620                     ret = AVERROR(ENOMEM);
 621                     goto fail;
 622                 }
 623                 goto done;
 624             }
 625             if (ret != AVERROR(ENOSYS))
 626                 goto fail;
 627         }
 628         tmp_ref = tmp_ctx->internal->source_device;
 629     }
 630
 631     ret = AVERROR(ENOSYS);
 632     goto fail;
 633
 634 done:
 635     *dst_ref_ptr = dst_ref;
 636     return 0;
 637
 638 fail:
 639     av_buffer_unref(&dst_ref);
 640     *dst_ref_ptr = NULL;
 641     return ret;
 642 }
 643
 644 static void ff_hwframe_unmap(void *opaque, uint8_t *data)
 645 {
 646     HWMapDescriptor *hwmap = (HWMapDescriptor*)data;
 647     AVHWFramesContext *ctx = opaque;
 648
 649     if (hwmap->unmap)
 650         hwmap->unmap(ctx, hwmap);
 651
 652     av_frame_free(&hwmap->source);
 653
 654     av_buffer_unref(&hwmap->hw_frames_ctx);
 655
 656     av_free(hwmap);
 657 }
 658
 659 int ff_hwframe_map_create(AVBufferRef *hwframe_ref,
 660                           AVFrame *dst, const AVFrame *src,
 661                           void (*unmap)(AVHWFramesContext *ctx,
 662                                         HWMapDescriptor *hwmap),
 663                           void *priv)
 664 {
 665     AVHWFramesContext *ctx = (AVHWFramesContext*)hwframe_ref->data;
 666     HWMapDescriptor *hwmap;
 667     int ret;
 668
 669     hwmap = av_mallocz(sizeof(*hwmap));
 670     if (!hwmap) {
 671         ret = AVERROR(ENOMEM);
 672         goto fail;
 673     }
 674
 675     hwmap->source = av_frame_alloc();
 676     if (!hwmap->source) {
 677         ret = AVERROR(ENOMEM);
 678         goto fail;
 679     }
 680     ret = av_frame_ref(hwmap->source, src);
 681     if (ret < 0)
 682         goto fail;
 683
 684     hwmap->hw_frames_ctx = av_buffer_ref(hwframe_ref);
 685     if (!hwmap->hw_frames_ctx) {
 686         ret = AVERROR(ENOMEM);
 687         goto fail;
 688     }
 689
 690     hwmap->unmap = unmap;
 691     hwmap->priv  = priv;
 692
 693     dst->buf[0] = av_buffer_create((uint8_t*)hwmap, sizeof(*hwmap),
 694                                    &ff_hwframe_unmap, ctx, 0);
 695     if (!dst->buf[0]) {
 696         ret = AVERROR(ENOMEM);
 697         goto fail;
 698     }
 699
 700     return 0;
 701
 702 fail:
 703     if (hwmap) {
 704         av_buffer_unref(&hwmap->hw_frames_ctx);
 705         av_frame_free(&hwmap->source);
 706     }
 707     av_free(hwmap);
 708     return ret;
 709 }
 710
 711 int av_hwframe_map(AVFrame *dst, const AVFrame *src, int flags)
 712 {
 713     AVHWFramesContext *src_frames, *dst_frames;
 714     HWMapDescriptor *hwmap;
 715     int ret;
 716
 717     if (src->hw_frames_ctx && dst->hw_frames_ctx) {
 718         src_frames = (AVHWFramesContext*)src->hw_frames_ctx->data;
 719         dst_frames = (AVHWFramesContext*)dst->hw_frames_ctx->data;
 720
 721         if ((src_frames == dst_frames &&
 722              src->format == dst_frames->sw_format &&
 723              dst->format == dst_frames->format) ||
 724             (src_frames->internal->source_frames &&
 725              src_frames->internal->source_frames->data ==
 726              (uint8_t*)dst_frames)) {
 727             // This is an unmap operation.  We don't need to directly
 728             // do anything here other than fill in the original frame,
 729             // because the real unmap will be invoked when the last
 730             // reference to the mapped frame disappears.
 731             if (!src->buf[0]) {
 732                 av_log(src_frames, AV_LOG_ERROR, "Invalid mapping "
 733                        "found when attempting unmap.\n");
 734                 return AVERROR(EINVAL);
 735             }
 736             hwmap = (HWMapDescriptor*)src->buf[0]->data;
 737             av_frame_unref(dst);
 738             return av_frame_ref(dst, hwmap->source);
 739         }
 740     }
 741
 742     if (src->hw_frames_ctx) {
 743         src_frames = (AVHWFramesContext*)src->hw_frames_ctx->data;
 744
 745         if (src_frames->format == src->format &&
 746             src_frames->internal->hw_type->map_from) {
 747             ret = src_frames->internal->hw_type->map_from(src_frames,
 748                                                           dst, src, flags);
 749             if (ret != AVERROR(ENOSYS))
 750                 return ret;
 751         }
 752     }
 753
 754     if (dst->hw_frames_ctx) {
 755         dst_frames = (AVHWFramesContext*)dst->hw_frames_ctx->data;
 756
 757         if (dst_frames->format == dst->format &&
 758             dst_frames->internal->hw_type->map_to) {
 759             ret = dst_frames->internal->hw_type->map_to(dst_frames,
 760                                                         dst, src, flags);
 761             if (ret != AVERROR(ENOSYS))
 762                 return ret;
 763         }
 764     }
 765
 766     return AVERROR(ENOSYS);
 767 }
 768
 769 int av_hwframe_ctx_create_derived(AVBufferRef **derived_frame_ctx,
 770                                   enum AVPixelFormat format,
 771                                   AVBufferRef *derived_device_ctx,
 772                                   AVBufferRef *source_frame_ctx,
 773                                   int flags)
 774 {
 775     AVBufferRef   *dst_ref = NULL;
 776     AVHWFramesContext *dst = NULL;
 777     AVHWFramesContext *src = (AVHWFramesContext*)source_frame_ctx->data;
 778     int ret;
 779
 780     if (src->internal->source_frames) {
 781         AVHWFramesContext *src_src =
 782             (AVHWFramesContext*)src->internal->source_frames->data;
 783         AVHWDeviceContext *dst_dev =
 784             (AVHWDeviceContext*)derived_device_ctx->data;
 785
 786         if (src_src->device_ctx == dst_dev) {
 787             // This is actually an unmapping, so we just return a
 788             // reference to the source frame context.
 789             *derived_frame_ctx =
 790                 av_buffer_ref(src->internal->source_frames);
 791             if (!*derived_frame_ctx) {
 792                 ret = AVERROR(ENOMEM);
 793                 goto fail;
 794             }
 795             return 0;
 796         }
 797     }
 798
 799     dst_ref = av_hwframe_ctx_alloc(derived_device_ctx);
 800     if (!dst_ref) {
 801         ret = AVERROR(ENOMEM);
 802         goto fail;
 803     }
 804
 805     dst = (AVHWFramesContext*)dst_ref->data;
 806
 807     dst->format    = format;
 808     dst->sw_format = src->sw_format;
 809     dst->width     = src->width;
 810     dst->height    = src->height;
 811
 812     dst->internal->source_frames = av_buffer_ref(source_frame_ctx);
 813     if (!dst->internal->source_frames) {
 814         ret = AVERROR(ENOMEM);
 815         goto fail;
 816     }
 817
 818     ret = av_hwframe_ctx_init(dst_ref);
 819     if (ret)
 820         goto fail;
 821
 822     *derived_frame_ctx = dst_ref;
 823     return 0;
 824
 825 fail:
 826     if (dst)
 827         av_buffer_unref(&dst->internal->source_frames);
 828     av_buffer_unref(&dst_ref);
 829     return ret;
 830 }