[ffvpx] Update ffvp9/ffvp8 to release 4.0.2

1 files changed, 873 insertions, 0 deletions

diff --git a/media/ffvpx/libavutil/hwcontext.c b/media/ffvpx/libavutil/hwcontext.c
new file mode 100644
index 000000000..70c556eca
--- /dev/null
+++ b/media/ffvpx/libavutil/hwcontext.c
@@ -0,0 +1,873 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "config.h"
+
+#include "buffer.h"
+#include "common.h"
+#include "hwcontext.h"
+#include "hwcontext_internal.h"
+#include "imgutils.h"
+#include "log.h"
+#include "mem.h"
+#include "pixdesc.h"
+#include "pixfmt.h"
+
+static const HWContextType * const hw_table[] = {
+#if CONFIG_CUDA
+    &ff_hwcontext_type_cuda,
+#endif
+#if CONFIG_D3D11VA
+    &ff_hwcontext_type_d3d11va,
+#endif
+#if CONFIG_LIBDRM
+    &ff_hwcontext_type_drm,
+#endif
+#if CONFIG_DXVA2
+    &ff_hwcontext_type_dxva2,
+#endif
+#if CONFIG_OPENCL
+    &ff_hwcontext_type_opencl,
+#endif
+#if CONFIG_QSV
+    &ff_hwcontext_type_qsv,
+#endif
+#if CONFIG_VAAPI
+    &ff_hwcontext_type_vaapi,
+#endif
+#if CONFIG_VDPAU
+    &ff_hwcontext_type_vdpau,
+#endif
+#if CONFIG_VIDEOTOOLBOX
+    &ff_hwcontext_type_videotoolbox,
+#endif
+#if CONFIG_MEDIACODEC
+    &ff_hwcontext_type_mediacodec,
+#endif
+    NULL,
+};
+
+static const char *const hw_type_names[] = {
+    [AV_HWDEVICE_TYPE_CUDA]   = "cuda",
+    [AV_HWDEVICE_TYPE_DRM]    = "drm",
+    [AV_HWDEVICE_TYPE_DXVA2]  = "dxva2",
+    [AV_HWDEVICE_TYPE_D3D11VA] = "d3d11va",
+    [AV_HWDEVICE_TYPE_OPENCL] = "opencl",
+    [AV_HWDEVICE_TYPE_QSV]    = "qsv",
+    [AV_HWDEVICE_TYPE_VAAPI]  = "vaapi",
+    [AV_HWDEVICE_TYPE_VDPAU]  = "vdpau",
+    [AV_HWDEVICE_TYPE_VIDEOTOOLBOX] = "videotoolbox",
+    [AV_HWDEVICE_TYPE_MEDIACODEC] = "mediacodec",
+};
+
+enum AVHWDeviceType av_hwdevice_find_type_by_name(const char *name)
+{
+    int type;
+    for (type = 0; type < FF_ARRAY_ELEMS(hw_type_names); type++) {
+        if (hw_type_names[type] && !strcmp(hw_type_names[type], name))
+            return type;
+    }
+    return AV_HWDEVICE_TYPE_NONE;
+}
+
+const char *av_hwdevice_get_type_name(enum AVHWDeviceType type)
+{
+    if (type > AV_HWDEVICE_TYPE_NONE &&
+        type < FF_ARRAY_ELEMS(hw_type_names))
+        return hw_type_names[type];
+    else
+        return NULL;
+}
+
+enum AVHWDeviceType av_hwdevice_iterate_types(enum AVHWDeviceType prev)
+{
+    enum AVHWDeviceType next;
+    int i, set = 0;
+    for (i = 0; hw_table[i]; i++) {
+        if (prev != AV_HWDEVICE_TYPE_NONE && hw_table[i]->type <= prev)
+            continue;
+        if (!set || hw_table[i]->type < next) {
+            next = hw_table[i]->type;
+            set = 1;
+        }
+    }
+    return set ? next : AV_HWDEVICE_TYPE_NONE;
+}
+
+static const AVClass hwdevice_ctx_class = {
+    .class_name = "AVHWDeviceContext",
+    .item_name  = av_default_item_name,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+static void hwdevice_ctx_free(void *opaque, uint8_t *data)
+{
+    AVHWDeviceContext *ctx = (AVHWDeviceContext*)data;
+
+    /* uninit might still want access the hw context and the user
+     * free() callback might destroy it, so uninit has to be called first */
+    if (ctx->internal->hw_type->device_uninit)
+        ctx->internal->hw_type->device_uninit(ctx);
+
+    if (ctx->free)
+        ctx->free(ctx);
+
+    av_buffer_unref(&ctx->internal->source_device);
+
+    av_freep(&ctx->hwctx);
+    av_freep(&ctx->internal->priv);
+    av_freep(&ctx->internal);
+    av_freep(&ctx);
+}
+
+AVBufferRef *av_hwdevice_ctx_alloc(enum AVHWDeviceType type)
+{
+    AVHWDeviceContext *ctx;
+    AVBufferRef *buf;
+    const HWContextType *hw_type = NULL;
+    int i;
+
+    for (i = 0; hw_table[i]; i++) {
+        if (hw_table[i]->type == type) {
+            hw_type = hw_table[i];
+            break;
+        }
+    }
+    if (!hw_type)
+        return NULL;
+
+    ctx = av_mallocz(sizeof(*ctx));
+    if (!ctx)
+        return NULL;
+
+    ctx->internal = av_mallocz(sizeof(*ctx->internal));
+    if (!ctx->internal)
+        goto fail;
+
+    if (hw_type->device_priv_size) {
+        ctx->internal->priv = av_mallocz(hw_type->device_priv_size);
+        if (!ctx->internal->priv)
+            goto fail;
+    }
+
+    if (hw_type->device_hwctx_size) {
+        ctx->hwctx = av_mallocz(hw_type->device_hwctx_size);
+        if (!ctx->hwctx)
+            goto fail;
+    }
+
+    buf = av_buffer_create((uint8_t*)ctx, sizeof(*ctx),
+                           hwdevice_ctx_free, NULL,
+                           AV_BUFFER_FLAG_READONLY);
+    if (!buf)
+        goto fail;
+
+    ctx->type     = type;
+    ctx->av_class = &hwdevice_ctx_class;
+
+    ctx->internal->hw_type = hw_type;
+
+    return buf;
+
+fail:
+    if (ctx->internal)
+        av_freep(&ctx->internal->priv);
+    av_freep(&ctx->internal);
+    av_freep(&ctx->hwctx);
+    av_freep(&ctx);
+    return NULL;
+}
+
+int av_hwdevice_ctx_init(AVBufferRef *ref)
+{
+    AVHWDeviceContext *ctx = (AVHWDeviceContext*)ref->data;
+    int ret;
+
+    if (ctx->internal->hw_type->device_init) {
+        ret = ctx->internal->hw_type->device_init(ctx);
+        if (ret < 0)
+            goto fail;
+    }
+
+    return 0;
+fail:
+    if (ctx->internal->hw_type->device_uninit)
+        ctx->internal->hw_type->device_uninit(ctx);
+    return ret;
+}
+
+static const AVClass hwframe_ctx_class = {
+    .class_name = "AVHWFramesContext",
+    .item_name  = av_default_item_name,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+static void hwframe_ctx_free(void *opaque, uint8_t *data)
+{
+    AVHWFramesContext *ctx = (AVHWFramesContext*)data;
+
+    if (ctx->internal->pool_internal)
+        av_buffer_pool_uninit(&ctx->internal->pool_internal);
+
+    if (ctx->internal->hw_type->frames_uninit)
+        ctx->internal->hw_type->frames_uninit(ctx);
+
+    if (ctx->free)
+        ctx->free(ctx);
+
+    av_buffer_unref(&ctx->internal->source_frames);
+
+    av_buffer_unref(&ctx->device_ref);
+
+    av_freep(&ctx->hwctx);
+    av_freep(&ctx->internal->priv);
+    av_freep(&ctx->internal);
+    av_freep(&ctx);
+}
+
+AVBufferRef *av_hwframe_ctx_alloc(AVBufferRef *device_ref_in)
+{
+    AVHWDeviceContext *device_ctx = (AVHWDeviceContext*)device_ref_in->data;
+    const HWContextType  *hw_type = device_ctx->internal->hw_type;
+    AVHWFramesContext *ctx;
+    AVBufferRef *buf, *device_ref = NULL;
+
+    ctx = av_mallocz(sizeof(*ctx));
+    if (!ctx)
+        return NULL;
+
+    ctx->internal = av_mallocz(sizeof(*ctx->internal));
+    if (!ctx->internal)
+        goto fail;
+
+    if (hw_type->frames_priv_size) {
+        ctx->internal->priv = av_mallocz(hw_type->frames_priv_size);
+        if (!ctx->internal->priv)
+            goto fail;
+    }
+
+    if (hw_type->frames_hwctx_size) {
+        ctx->hwctx = av_mallocz(hw_type->frames_hwctx_size);
+        if (!ctx->hwctx)
+            goto fail;
+    }
+
+    device_ref = av_buffer_ref(device_ref_in);
+    if (!device_ref)
+        goto fail;
+
+    buf = av_buffer_create((uint8_t*)ctx, sizeof(*ctx),
+                           hwframe_ctx_free, NULL,
+                           AV_BUFFER_FLAG_READONLY);
+    if (!buf)
+        goto fail;
+
+    ctx->av_class   = &hwframe_ctx_class;
+    ctx->device_ref = device_ref;
+    ctx->device_ctx = device_ctx;
+    ctx->format     = AV_PIX_FMT_NONE;
+    ctx->sw_format  = AV_PIX_FMT_NONE;
+
+    ctx->internal->hw_type = hw_type;
+
+    return buf;
+
+fail:
+    if (device_ref)
+        av_buffer_unref(&device_ref);
+    if (ctx->internal)
+        av_freep(&ctx->internal->priv);
+    av_freep(&ctx->internal);
+    av_freep(&ctx->hwctx);
+    av_freep(&ctx);
+    return NULL;
+}
+
+static int hwframe_pool_prealloc(AVBufferRef *ref)
+{
+    AVHWFramesContext *ctx = (AVHWFramesContext*)ref->data;
+    AVFrame **frames;
+    int i, ret = 0;
+
+    frames = av_mallocz_array(ctx->initial_pool_size, sizeof(*frames));
+    if (!frames)
+        return AVERROR(ENOMEM);
+
+    for (i = 0; i < ctx->initial_pool_size; i++) {
+        frames[i] = av_frame_alloc();
+        if (!frames[i])
+            goto fail;
+
+        ret = av_hwframe_get_buffer(ref, frames[i], 0);
+        if (ret < 0)
+            goto fail;
+    }
+
+fail:
+    for (i = 0; i < ctx->initial_pool_size; i++)
+        av_frame_free(&frames[i]);
+    av_freep(&frames);
+
+    return ret;
+}
+
+int av_hwframe_ctx_init(AVBufferRef *ref)
+{
+    AVHWFramesContext *ctx = (AVHWFramesContext*)ref->data;
+    const enum AVPixelFormat *pix_fmt;
+    int ret;
+
+    if (ctx->internal->source_frames) {
+        /* A derived frame context is already initialised. */
+        return 0;
+    }
+
+    /* validate the pixel format */
+    for (pix_fmt = ctx->internal->hw_type->pix_fmts; *pix_fmt != AV_PIX_FMT_NONE; pix_fmt++) {
+        if (*pix_fmt == ctx->format)
+            break;
+    }
+    if (*pix_fmt == AV_PIX_FMT_NONE) {
+        av_log(ctx, AV_LOG_ERROR,
+               "The hardware pixel format '%s' is not supported by the device type '%s'\n",
+               av_get_pix_fmt_name(ctx->format), ctx->internal->hw_type->name);
+        return AVERROR(ENOSYS);
+    }
+
+    /* validate the dimensions */
+    ret = av_image_check_size(ctx->width, ctx->height, 0, ctx);
+    if (ret < 0)
+        return ret;
+
+    /* format-specific init */
+    if (ctx->internal->hw_type->frames_init) {
+        ret = ctx->internal->hw_type->frames_init(ctx);
+        if (ret < 0)
+            goto fail;
+    }
+
+    if (ctx->internal->pool_internal && !ctx->pool)
+        ctx->pool = ctx->internal->pool_internal;
+
+    /* preallocate the frames in the pool, if requested */
+    if (ctx->initial_pool_size > 0) {
+        ret = hwframe_pool_prealloc(ref);
+        if (ret < 0)
+            goto fail;
+    }
+
+    return 0;
+fail:
+    if (ctx->internal->hw_type->frames_uninit)
+        ctx->internal->hw_type->frames_uninit(ctx);
+    return ret;
+}
+
+int av_hwframe_transfer_get_formats(AVBufferRef *hwframe_ref,
+                                    enum AVHWFrameTransferDirection dir,
+                                    enum AVPixelFormat **formats, int flags)
+{
+    AVHWFramesContext *ctx = (AVHWFramesContext*)hwframe_ref->data;
+
+    if (!ctx->internal->hw_type->transfer_get_formats)
+        return AVERROR(ENOSYS);
+
+    return ctx->internal->hw_type->transfer_get_formats(ctx, dir, formats);
+}
+
+static int transfer_data_alloc(AVFrame *dst, const AVFrame *src, int flags)
+{
+    AVHWFramesContext *ctx = (AVHWFramesContext*)src->hw_frames_ctx->data;
+    AVFrame *frame_tmp;
+    int ret = 0;
+
+    frame_tmp = av_frame_alloc();
+    if (!frame_tmp)
+        return AVERROR(ENOMEM);
+
+    /* if the format is set, use that
+     * otherwise pick the first supported one */
+    if (dst->format >= 0) {
+        frame_tmp->format = dst->format;
+    } else {
+        enum AVPixelFormat *formats;
+
+        ret = av_hwframe_transfer_get_formats(src->hw_frames_ctx,
+                                              AV_HWFRAME_TRANSFER_DIRECTION_FROM,
+                                              &formats, 0);
+        if (ret < 0)
+            goto fail;
+        frame_tmp->format = formats[0];
+        av_freep(&formats);
+    }
+    frame_tmp->width  = ctx->width;
+    frame_tmp->height = ctx->height;
+
+    ret = av_frame_get_buffer(frame_tmp, 32);
+    if (ret < 0)
+        goto fail;
+
+    ret = av_hwframe_transfer_data(frame_tmp, src, flags);
+    if (ret < 0)
+        goto fail;
+
+    frame_tmp->width  = src->width;
+    frame_tmp->height = src->height;
+
+    av_frame_move_ref(dst, frame_tmp);
+
+fail:
+    av_frame_free(&frame_tmp);
+    return ret;
+}
+
+int av_hwframe_transfer_data(AVFrame *dst, const AVFrame *src, int flags)
+{
+    AVHWFramesContext *ctx;
+    int ret;
+
+    if (!dst->buf[0])
+        return transfer_data_alloc(dst, src, flags);
+
+    if (src->hw_frames_ctx) {
+        ctx = (AVHWFramesContext*)src->hw_frames_ctx->data;
+
+        ret = ctx->internal->hw_type->transfer_data_from(ctx, dst, src);
+        if (ret < 0)
+            return ret;
+    } else if (dst->hw_frames_ctx) {
+        ctx = (AVHWFramesContext*)dst->hw_frames_ctx->data;
+
+        ret = ctx->internal->hw_type->transfer_data_to(ctx, dst, src);
+        if (ret < 0)
+            return ret;
+    } else
+        return AVERROR(ENOSYS);
+
+    return 0;
+}
+
+int av_hwframe_get_buffer(AVBufferRef *hwframe_ref, AVFrame *frame, int flags)
+{
+    AVHWFramesContext *ctx = (AVHWFramesContext*)hwframe_ref->data;
+    int ret;
+
+    if (ctx->internal->source_frames) {
+        // This is a derived frame context, so we allocate in the source
+        // and map the frame immediately.
+        AVFrame *src_frame;
+
+        frame->format = ctx->format;
+        frame->hw_frames_ctx = av_buffer_ref(hwframe_ref);
+        if (!frame->hw_frames_ctx)
+            return AVERROR(ENOMEM);
+
+        src_frame = av_frame_alloc();
+        if (!src_frame)
+            return AVERROR(ENOMEM);
+
+        ret = av_hwframe_get_buffer(ctx->internal->source_frames,
+                                    src_frame, 0);
+        if (ret < 0) {
+            av_frame_free(&src_frame);
+            return ret;
+        }
+
+        ret = av_hwframe_map(frame, src_frame,
+                             ctx->internal->source_allocation_map_flags);
+        if (ret) {
+            av_log(ctx, AV_LOG_ERROR, "Failed to map frame into derived "
+                   "frame context: %d.\n", ret);
+            av_frame_free(&src_frame);
+            return ret;
+        }
+
+        // Free the source frame immediately - the mapped frame still
+        // contains a reference to it.
+        av_frame_free(&src_frame);
+
+        return 0;
+    }
+
+    if (!ctx->internal->hw_type->frames_get_buffer)
+        return AVERROR(ENOSYS);
+
+    if (!ctx->pool)
+        return AVERROR(EINVAL);
+
+    frame->hw_frames_ctx = av_buffer_ref(hwframe_ref);
+    if (!frame->hw_frames_ctx)
+        return AVERROR(ENOMEM);
+
+    ret = ctx->internal->hw_type->frames_get_buffer(ctx, frame);
+    if (ret < 0) {
+        av_buffer_unref(&frame->hw_frames_ctx);
+        return ret;
+    }
+
+    return 0;
+}
+
+void *av_hwdevice_hwconfig_alloc(AVBufferRef *ref)
+{
+    AVHWDeviceContext *ctx = (AVHWDeviceContext*)ref->data;
+    const HWContextType  *hw_type = ctx->internal->hw_type;
+
+    if (hw_type->device_hwconfig_size == 0)
+        return NULL;
+
+    return av_mallocz(hw_type->device_hwconfig_size);
+}
+
+AVHWFramesConstraints *av_hwdevice_get_hwframe_constraints(AVBufferRef *ref,
+                                                           const void *hwconfig)
+{
+    AVHWDeviceContext *ctx = (AVHWDeviceContext*)ref->data;
+    const HWContextType  *hw_type = ctx->internal->hw_type;
+    AVHWFramesConstraints *constraints;
+
+    if (!hw_type->frames_get_constraints)
+        return NULL;
+
+    constraints = av_mallocz(sizeof(*constraints));
+    if (!constraints)
+        return NULL;
+
+    constraints->min_width = constraints->min_height = 0;
+    constraints->max_width = constraints->max_height = INT_MAX;
+
+    if (hw_type->frames_get_constraints(ctx, hwconfig, constraints) >= 0) {
+        return constraints;
+    } else {
+        av_hwframe_constraints_free(&constraints);
+        return NULL;
+    }
+}
+
+void av_hwframe_constraints_free(AVHWFramesConstraints **constraints)
+{
+    if (*constraints) {
+        av_freep(&(*constraints)->valid_hw_formats);
+        av_freep(&(*constraints)->valid_sw_formats);
+    }
+    av_freep(constraints);
+}
+
+int av_hwdevice_ctx_create(AVBufferRef **pdevice_ref, enum AVHWDeviceType type,
+                           const char *device, AVDictionary *opts, int flags)
+{
+    AVBufferRef *device_ref = NULL;
+    AVHWDeviceContext *device_ctx;
+    int ret = 0;
+
+    device_ref = av_hwdevice_ctx_alloc(type);
+    if (!device_ref) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+    device_ctx = (AVHWDeviceContext*)device_ref->data;
+
+    if (!device_ctx->internal->hw_type->device_create) {
+        ret = AVERROR(ENOSYS);
+        goto fail;
+    }
+
+    ret = device_ctx->internal->hw_type->device_create(device_ctx, device,
+                                                       opts, flags);
+    if (ret < 0)
+        goto fail;
+
+    ret = av_hwdevice_ctx_init(device_ref);
+    if (ret < 0)
+        goto fail;
+
+    *pdevice_ref = device_ref;
+    return 0;
+fail:
+    av_buffer_unref(&device_ref);
+    *pdevice_ref = NULL;
+    return ret;
+}
+
+int av_hwdevice_ctx_create_derived(AVBufferRef **dst_ref_ptr,
+                                   enum AVHWDeviceType type,
+                                   AVBufferRef *src_ref, int flags)
+{
+    AVBufferRef *dst_ref = NULL, *tmp_ref;
+    AVHWDeviceContext *dst_ctx, *tmp_ctx;
+    int ret = 0;
+
+    tmp_ref = src_ref;
+    while (tmp_ref) {
+        tmp_ctx = (AVHWDeviceContext*)tmp_ref->data;
+        if (tmp_ctx->type == type) {
+            dst_ref = av_buffer_ref(tmp_ref);
+            if (!dst_ref) {
+                ret = AVERROR(ENOMEM);
+                goto fail;
+            }
+            goto done;
+        }
+        tmp_ref = tmp_ctx->internal->source_device;
+    }
+
+    dst_ref = av_hwdevice_ctx_alloc(type);
+    if (!dst_ref) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+    dst_ctx = (AVHWDeviceContext*)dst_ref->data;
+
+    tmp_ref = src_ref;
+    while (tmp_ref) {
+        tmp_ctx = (AVHWDeviceContext*)tmp_ref->data;
+        if (dst_ctx->internal->hw_type->device_derive) {
+            ret = dst_ctx->internal->hw_type->device_derive(dst_ctx,
+                                                            tmp_ctx,
+                                                            flags);
+            if (ret == 0) {
+                dst_ctx->internal->source_device = av_buffer_ref(src_ref);
+                if (!dst_ctx->internal->source_device) {
+                    ret = AVERROR(ENOMEM);
+                    goto fail;
+                }
+                goto done;
+            }
+            if (ret != AVERROR(ENOSYS))
+                goto fail;
+        }
+        tmp_ref = tmp_ctx->internal->source_device;
+    }
+
+    ret = AVERROR(ENOSYS);
+    goto fail;
+
+done:
+    ret = av_hwdevice_ctx_init(dst_ref);
+    if (ret < 0)
+        goto fail;
+
+    *dst_ref_ptr = dst_ref;
+    return 0;
+
+fail:
+    av_buffer_unref(&dst_ref);
+    *dst_ref_ptr = NULL;
+    return ret;
+}
+
+static void ff_hwframe_unmap(void *opaque, uint8_t *data)
+{
+    HWMapDescriptor *hwmap = (HWMapDescriptor*)data;
+    AVHWFramesContext *ctx = opaque;
+
+    if (hwmap->unmap)
+        hwmap->unmap(ctx, hwmap);
+
+    av_frame_free(&hwmap->source);
+
+    av_buffer_unref(&hwmap->hw_frames_ctx);
+
+    av_free(hwmap);
+}
+
+int ff_hwframe_map_create(AVBufferRef *hwframe_ref,
+                          AVFrame *dst, const AVFrame *src,
+                          void (*unmap)(AVHWFramesContext *ctx,
+                                        HWMapDescriptor *hwmap),
+                          void *priv)
+{
+    AVHWFramesContext *ctx = (AVHWFramesContext*)hwframe_ref->data;
+    HWMapDescriptor *hwmap;
+    int ret;
+
+    hwmap = av_mallocz(sizeof(*hwmap));
+    if (!hwmap) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    hwmap->source = av_frame_alloc();
+    if (!hwmap->source) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+    ret = av_frame_ref(hwmap->source, src);
+    if (ret < 0)
+        goto fail;
+
+    hwmap->hw_frames_ctx = av_buffer_ref(hwframe_ref);
+    if (!hwmap->hw_frames_ctx) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    hwmap->unmap = unmap;
+    hwmap->priv  = priv;
+
+    dst->buf[0] = av_buffer_create((uint8_t*)hwmap, sizeof(*hwmap),
+                                   &ff_hwframe_unmap, ctx, 0);
+    if (!dst->buf[0]) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    return 0;
+
+fail:
+    if (hwmap) {
+        av_buffer_unref(&hwmap->hw_frames_ctx);
+        av_frame_free(&hwmap->source);
+    }
+    av_free(hwmap);
+    return ret;
+}
+
+int av_hwframe_map(AVFrame *dst, const AVFrame *src, int flags)
+{
+    AVHWFramesContext *src_frames, *dst_frames;
+    HWMapDescriptor *hwmap;
+    int ret;
+
+    if (src->hw_frames_ctx && dst->hw_frames_ctx) {
+        src_frames = (AVHWFramesContext*)src->hw_frames_ctx->data;
+        dst_frames = (AVHWFramesContext*)dst->hw_frames_ctx->data;
+
+        if ((src_frames == dst_frames &&
+             src->format == dst_frames->sw_format &&
+             dst->format == dst_frames->format) ||
+            (src_frames->internal->source_frames &&
+             src_frames->internal->source_frames->data ==
+             (uint8_t*)dst_frames)) {
+            // This is an unmap operation.  We don't need to directly
+            // do anything here other than fill in the original frame,
+            // because the real unmap will be invoked when the last
+            // reference to the mapped frame disappears.
+            if (!src->buf[0]) {
+                av_log(src_frames, AV_LOG_ERROR, "Invalid mapping "
+                       "found when attempting unmap.\n");
+                return AVERROR(EINVAL);
+            }
+            hwmap = (HWMapDescriptor*)src->buf[0]->data;
+            av_frame_unref(dst);
+            return av_frame_ref(dst, hwmap->source);
+        }
+    }
+
+    if (src->hw_frames_ctx) {
+        src_frames = (AVHWFramesContext*)src->hw_frames_ctx->data;
+
+        if (src_frames->format == src->format &&
+            src_frames->internal->hw_type->map_from) {
+            ret = src_frames->internal->hw_type->map_from(src_frames,
+                                                          dst, src, flags);
+            if (ret != AVERROR(ENOSYS))
+                return ret;
+        }
+    }
+
+    if (dst->hw_frames_ctx) {
+        dst_frames = (AVHWFramesContext*)dst->hw_frames_ctx->data;
+
+        if (dst_frames->format == dst->format &&
+            dst_frames->internal->hw_type->map_to) {
+            ret = dst_frames->internal->hw_type->map_to(dst_frames,
+                                                        dst, src, flags);
+            if (ret != AVERROR(ENOSYS))
+                return ret;
+        }
+    }
+
+    return AVERROR(ENOSYS);
+}
+
+int av_hwframe_ctx_create_derived(AVBufferRef **derived_frame_ctx,
+                                  enum AVPixelFormat format,
+                                  AVBufferRef *derived_device_ctx,
+                                  AVBufferRef *source_frame_ctx,
+                                  int flags)
+{
+    AVBufferRef   *dst_ref = NULL;
+    AVHWFramesContext *dst = NULL;
+    AVHWFramesContext *src = (AVHWFramesContext*)source_frame_ctx->data;
+    int ret;
+
+    if (src->internal->source_frames) {
+        AVHWFramesContext *src_src =
+            (AVHWFramesContext*)src->internal->source_frames->data;
+        AVHWDeviceContext *dst_dev =
+            (AVHWDeviceContext*)derived_device_ctx->data;
+
+        if (src_src->device_ctx == dst_dev) {
+            // This is actually an unmapping, so we just return a
+            // reference to the source frame context.
+            *derived_frame_ctx =
+                av_buffer_ref(src->internal->source_frames);
+            if (!*derived_frame_ctx) {
+                ret = AVERROR(ENOMEM);
+                goto fail;
+            }
+            return 0;
+        }
+    }
+
+    dst_ref = av_hwframe_ctx_alloc(derived_device_ctx);
+    if (!dst_ref) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    dst = (AVHWFramesContext*)dst_ref->data;
+
+    dst->format    = format;
+    dst->sw_format = src->sw_format;
+    dst->width     = src->width;
+    dst->height    = src->height;
+
+    dst->internal->source_frames = av_buffer_ref(source_frame_ctx);
+    if (!dst->internal->source_frames) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    dst->internal->source_allocation_map_flags =
+        flags & (AV_HWFRAME_MAP_READ      |
+                 AV_HWFRAME_MAP_WRITE     |
+                 AV_HWFRAME_MAP_OVERWRITE |
+                 AV_HWFRAME_MAP_DIRECT);
+
+    ret = AVERROR(ENOSYS);
+    if (src->internal->hw_type->frames_derive_from)
+        ret = src->internal->hw_type->frames_derive_from(dst, src, flags);
+    if (ret == AVERROR(ENOSYS) &&
+        dst->internal->hw_type->frames_derive_to)
+        ret = dst->internal->hw_type->frames_derive_to(dst, src, flags);
+    if (ret == AVERROR(ENOSYS))
+        ret = 0;
+    if (ret)
+        goto fail;
+
+    *derived_frame_ctx = dst_ref;
+    return 0;
+
+fail:
+    if (dst)
+        av_buffer_unref(&dst->internal->source_frames);
+    av_buffer_unref(&dst_ref);
+    return ret;
+}