lavu: add a framework for handling hwaccel frames

doc/APIchanges

@@ -15,6 +15,8 @@ API changes, most recent first:
 
 2016-xx-xx - lavu 55.6.0
   xxxxxxx buffer.h - Add av_buffer_pool_init2().
+  xxxxxxx hwcontext.h - Add a new installed header hwcontext.h with a new API
+                        for handling hwaccel frames.
 
 2016-xx-xx - xxxxxxx - lavf 57.3.0 - avformat.h
   Add AVFormatContext.opaque, io_open and io_close, allowing custom IO

libavutil/Makefile

@@ -23,6 +23,7 @@ HEADERS = adler32.h                                                     \
           file.h                                                        \
           frame.h                                                       \
           hmac.h                                                        \
+          hwcontext.h                                                   \
           imgutils.h                                                    \
           intfloat.h                                                    \
           intreadwrite.h                                                \
@@ -78,6 +79,7 @@ OBJS = adler32.o                                                        \
        float_dsp.o                                                      \
        frame.o                                                          \
        hmac.o                                                           \
+       hwcontext.o                                                      \
        imgutils.o                                                       \
        intmath.o                                                        \
        lfg.o                                                            \

libavutil/frame.c

@@ -251,6 +251,14 @@ int av_frame_ref(AVFrame *dst, const AVFrame *src)
         }
     }
 
+    if (src->hw_frames_ctx) {
+        dst->hw_frames_ctx = av_buffer_ref(src->hw_frames_ctx);
+        if (!dst->hw_frames_ctx) {
+            ret = AVERROR(ENOMEM);
+            goto fail;
+        }
+    }
+
     /* duplicate extended data */
     if (src->extended_data != src->data) {
         int ch = av_get_channel_layout_nb_channels(src->channel_layout);
@@ -303,6 +311,9 @@ void av_frame_unref(AVFrame *frame)
     for (i = 0; i < frame->nb_extended_buf; i++)
         av_buffer_unref(&frame->extended_buf[i]);
     av_freep(&frame->extended_buf);
+
+    av_buffer_unref(&frame->hw_frames_ctx);
+
     get_frame_defaults(frame);
 }
 

libavutil/frame.h

@@ -354,6 +354,12 @@ typedef struct AVFrame {
     enum AVColorSpace colorspace;
 
     enum AVChromaLocation chroma_location;
+
+    /**
+     * For hwaccel-format frames, this should be a reference to the
+     * AVHWFramesContext describing the frame.
+     */
+    AVBufferRef *hw_frames_ctx;
 } AVFrame;
 
 /**

libavutil/hwcontext_internal.h

+/*
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVUTIL_HWCONTEXT_INTERNAL_H
+#define AVUTIL_HWCONTEXT_INTERNAL_H
+
+#include <stddef.h>
+
+#include "buffer.h"
+#include "hwcontext.h"
+#include "frame.h"
+#include "pixfmt.h"
+
+typedef struct HWContextType {
+    enum AVHWDeviceType type;
+    const char         *name;
+
+    /**
+     * An array of pixel formats supported by the AVHWFramesContext instances
+     * Terminated by AV_PIX_FMT_NONE.
+     */
+    const enum AVPixelFormat *pix_fmts;
+
+    /**
+     * size of the public hardware-specific context,
+     * i.e. AVHWDeviceContext.hwctx
+     */
+    size_t             device_hwctx_size;
+    /**
+     * size of the private data, i.e.
+     * AVHWDeviceInternal.priv
+     */
+    size_t             device_priv_size;
+
+    /**
+     * size of the public frame pool hardware-specific context,
+     * i.e. AVHWFramesContext.hwctx
+     */
+    size_t             frames_hwctx_size;
+    /**
+     * size of the private data, i.e.
+     * AVHWFramesInternal.priv
+     */
+    size_t             frames_priv_size;
+
+    int              (*device_init)(AVHWDeviceContext *ctx);
+    void             (*device_uninit)(AVHWDeviceContext *ctx);
+
+    int              (*frames_init)(AVHWFramesContext *ctx);
+    void             (*frames_uninit)(AVHWFramesContext *ctx);
+
+    int              (*frames_get_buffer)(AVHWFramesContext *ctx, AVFrame *frame);
+    int              (*transfer_get_formats)(AVHWFramesContext *ctx,
+                                             enum AVHWFrameTransferDirection dir,
+                                             enum AVPixelFormat **formats);
+    int              (*transfer_data_to)(AVHWFramesContext *ctx, AVFrame *dst,
+                                         const AVFrame *src);
+    int              (*transfer_data_from)(AVHWFramesContext *ctx, AVFrame *dst,
+                                           const AVFrame *src);
+} HWContextType;
+
+struct AVHWDeviceInternal {
+    const HWContextType *hw_type;
+    void                *priv;
+};
+
+struct AVHWFramesInternal {
+    const HWContextType *hw_type;
+    void                *priv;
+
+    AVBufferPool *pool_internal;
+};
+
+#endif /* AVUTIL_HWCONTEXT_INTERNAL_H */