lavc: Add codec metadata to indicate hardware support

doc/APIchanges

@@ -13,6 +13,9 @@ libavutil:     2017-03-23
 
 API changes, most recent first:
 
+2017-xx-xx - xxxxxxx - lavc 58.6.0 - avcodec.h
+  Add AVCodecHWConfig and avcodec_get_hw_config().
+
 2017-xx-xx - xxxxxxx - lavu 56.7.0 - stereo3d.h
   Add view field to AVStereo3D structure and AVStereo3DView enum.
 

libavcodec/avcodec.h

@@ -35,6 +35,7 @@
 #include "libavutil/cpu.h"
 #include "libavutil/dict.h"
 #include "libavutil/frame.h"
+#include "libavutil/hwcontext.h"
 #include "libavutil/log.h"
 #include "libavutil/pixfmt.h"
 #include "libavutil/rational.h"
@@ -2748,6 +2749,61 @@ typedef struct AVProfile {
     const char *name; ///< short name for the profile
 } AVProfile;
 
+enum {
+    /**
+     * The codec supports this format via the hw_device_ctx interface.
+     *
+     * When selecting this format, AVCodecContext.hw_device_ctx should
+     * have been set to a device of the specified type before calling
+     * avcodec_open2().
+     */
+    AV_CODEC_HW_CONFIG_METHOD_HW_DEVICE_CTX = 0x01,
+    /**
+     * The codec supports this format via the hw_frames_ctx interface.
+     *
+     * When selecting this format for a decoder,
+     * AVCodecContext.hw_frames_ctx should be set to a suitable frames
+     * context inside the get_format() callback.  The frames context
+     * must have been created on a device of the specified type.
+     */
+    AV_CODEC_HW_CONFIG_METHOD_HW_FRAMES_CTX = 0x02,
+    /**
+     * The codec supports this format by some internal method.
+     *
+     * This format can be selected without any additional configuration -
+     * no device or frames context is required.
+     */
+    AV_CODEC_HW_CONFIG_METHOD_INTERNAL      = 0x04,
+    /**
+     * The codec supports this format by some ad-hoc method.
+     *
+     * Additional settings and/or function calls are required.  See the
+     * codec-specific documentation for details.  (Methods requiring
+     * this sort of configuration are deprecated and others should be
+     * used in preference.)
+     */
+    AV_CODEC_HW_CONFIG_METHOD_AD_HOC        = 0x08,
+};
+
+typedef struct AVCodecHWConfig {
+    /**
+     * A hardware pixel format which the codec can use.
+     */
+    enum AVPixelFormat pix_fmt;
+    /**
+     * Bit set of AV_CODEC_HW_CONFIG_METHOD_* flags, describing the possible
+     * setup methods which can be used with this configuration.
+     */
+    int methods;
+    /**
+     * The device type associated with the configuration.
+     *
+     * Must be set for AV_CODEC_HW_CONFIG_METHOD_HW_DEVICE_CTX and
+     * AV_CODEC_HW_CONFIG_METHOD_HW_FRAMES_CTX, otherwise unused.
+     */
+    enum AVHWDeviceType device_type;
+} AVCodecHWConfig;
+
 typedef struct AVCodecDefault AVCodecDefault;
 
 struct AVSubtitle;
@@ -2884,8 +2940,26 @@ typedef struct AVCodec {
      * packets before decoding.
      */
     const char *bsfs;
+
+    /**
+     * Array of pointers to hardware configurations supported by the codec,
+     * or NULL if no hardware supported.  The array is terminated by a NULL
+     * pointer.
+     *
+     * The user can only access this field via avcodec_get_hw_config().
+     */
+    const struct AVCodecHWConfigInternal **hw_configs;
 } AVCodec;
 
+/**
+ * Retrieve supported hardware configurations for a codec.
+ *
+ * Values of index from zero to some maximum return the indexed configuration
+ * descriptor; all other values return NULL.  If the codec does not support
+ * any hardware configurations then it will always return NULL.
+ */
+const AVCodecHWConfig *avcodec_get_hw_config(const AVCodec *codec, int index);
+
 /**
  * @defgroup lavc_hwaccel AVHWAccel
  * @{

libavcodec/hwaccel.h

@@ -19,6 +19,24 @@
 #ifndef AVCODEC_HWACCEL_H
 #define AVCODEC_HWACCEL_H
 
+#include "avcodec.h"
+
+
 #define HWACCEL_CAP_ASYNC_SAFE      (1 << 0)
 
+
+typedef struct AVCodecHWConfigInternal {
+    /**
+     * This is the structure which will be returned to the user by
+     * avcodec_get_hw_config().
+     */
+    AVCodecHWConfig public;
+    /**
+     * If this configuration uses a hwaccel, a pointer to it.
+     * If not, NULL.
+     */
+    const AVHWAccel *hwaccel;
+} AVCodecHWConfigInternal;
+
+
 #endif /* AVCODEC_HWACCEL_H */

libavcodec/utils.c

@@ -41,6 +41,7 @@
 #include "libavutil/dict.h"
 #include "avcodec.h"
 #include "decode.h"
+#include "hwaccel.h"
 #include "libavutil/opt.h"
 #include "me_cmp.h"
 #include "mpegvideo.h"
@@ -1335,6 +1336,17 @@ int ff_match_2uint16(const uint16_t(*tab)[2], int size, int a, int b)
     return i;
 }
 
+const AVCodecHWConfig *avcodec_get_hw_config(const AVCodec *codec, int index)
+{
+    int i;
+    if (!codec->hw_configs || index < 0)
+        return NULL;
+    for (i = 0; i <= index; i++)
+        if (!codec->hw_configs[i])
+            return NULL;
+    return &codec->hw_configs[index]->public;
+}
+
 static AVHWAccel *first_hwaccel = NULL;
 
 void av_register_hwaccel(AVHWAccel *hwaccel)

libavcodec/version.h

@@ -28,7 +28,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVCODEC_VERSION_MAJOR 58
-#define LIBAVCODEC_VERSION_MINOR  5
+#define LIBAVCODEC_VERSION_MINOR  6
 #define LIBAVCODEC_VERSION_MICRO  0
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \