avcodec/codec_internal: Add FFCodec, hide internal part of AVCodec

Up until now, codec.h contains both public and private parts
of AVCodec. This exposes the internals of AVCodec to users
and leads them into the temptation of actually using them
and forces us to forward-declare structures and types that
users can't use at all.

This commit changes this by adding a new structure FFCodec to
codec_internal.h that extends AVCodec, i.e. contains the public
AVCodec as first member; the private fields of AVCodec are moved
to this structure, leaving codec.h clean.

Reviewed-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

1 files changed, 131 insertions, 3 deletions

diff --git a/libavcodec/codec_internal.h b/libavcodec/codec_internal.h
index 07c8e943e2..7e317a6396 100644
--- a/libavcodec/codec_internal.h
+++ b/libavcodec/codec_internal.h
@@ -19,6 +19,11 @@
 #ifndef AVCODEC_CODEC_INTERNAL_H
 #define AVCODEC_CODEC_INTERNAL_H
 
+#include <stdint.h>
+
+#include "libavutil/attributes.h"
+#include "codec.h"
+
 /**
  * The codec does not modify any global variables in the init function,
  * allowing to call the init function without locking any global mutexes.
@@ -70,13 +75,136 @@
 #define FF_CODEC_CAP_SETS_FRAME_PROPS       (1 << 8)
 
 /**
- * AVCodec.codec_tags termination value
+ * FFCodec.codec_tags termination value
  */
 #define FF_CODEC_TAGS_END -1
 
-struct AVCodecDefault {
+typedef struct AVCodecDefault {
     const char *key;
     const char *value;
-};
+} AVCodecDefault;
+
+struct AVCodecContext;
+struct AVSubtitle;
+struct AVPacket;
+
+typedef struct FFCodec {
+    /**
+     * The public AVCodec. See codec.h for it.
+     */
+    AVCodec p;
+
+    /**
+     * Internal codec capabilities FF_CODEC_CAP_*.
+     */
+    int caps_internal;
+
+    int priv_data_size;
+    /**
+     * @name Frame-level threading support functions
+     * @{
+     */
+    /**
+     * Copy necessary context variables from a previous thread context to the current one.
+     * If not defined, the next thread will start automatically; otherwise, the codec
+     * must call ff_thread_finish_setup().
+     *
+     * dst and src will (rarely) point to the same context, in which case memcpy should be skipped.
+     */
+    int (*update_thread_context)(struct AVCodecContext *dst, const struct AVCodecContext *src);
+
+    /**
+     * Copy variables back to the user-facing context
+     */
+    int (*update_thread_context_for_user)(struct AVCodecContext *dst, const struct AVCodecContext *src);
+    /** @} */
+
+    /**
+     * Private codec-specific defaults.
+     */
+    const AVCodecDefault *defaults;
+
+    /**
+     * Initialize codec static data, called from av_codec_iterate().
+     *
+     * This is not intended for time consuming operations as it is
+     * run for every codec regardless of that codec being used.
+     */
+    void (*init_static_data)(struct FFCodec *codec);
+
+    int (*init)(struct AVCodecContext *);
+    int (*encode_sub)(struct AVCodecContext *, uint8_t *buf, int buf_size,
+                      const struct AVSubtitle *sub);
+    /**
+     * Encode data to an AVPacket.
+     *
+     * @param      avctx          codec context
+     * @param      avpkt          output AVPacket
+     * @param[in]  frame          AVFrame containing the raw data to be encoded
+     * @param[out] got_packet_ptr encoder sets to 0 or 1 to indicate that a
+     *                            non-empty packet was returned in avpkt.
+     * @return 0 on success, negative error code on failure
+     */
+    int (*encode2)(struct AVCodecContext *avctx, struct AVPacket *avpkt,
+                   const struct AVFrame *frame, int *got_packet_ptr);
+    /**
+     * Decode picture or subtitle data.
+     *
+     * @param      avctx          codec context
+     * @param      outdata        codec type dependent output struct
+     * @param[out] got_frame_ptr  decoder sets to 0 or 1 to indicate that a
+     *                            non-empty frame or subtitle was returned in
+     *                            outdata.
+     * @param[in]  avpkt          AVPacket containing the data to be decoded
+     * @return amount of bytes read from the packet on success, negative error
+     *         code on failure
+     */
+    int (*decode)(struct AVCodecContext *avctx, void *outdata,
+                  int *got_frame_ptr, struct AVPacket *avpkt);
+    int (*close)(struct AVCodecContext *);
+    /**
+     * Encode API with decoupled frame/packet dataflow. This function is called
+     * to get one output packet. It should call ff_encode_get_frame() to obtain
+     * input data.
+     */
+    int (*receive_packet)(struct AVCodecContext *avctx, struct AVPacket *avpkt);
+
+    /**
+     * Decode API with decoupled packet/frame dataflow. This function is called
+     * to get one output frame. It should call ff_decode_get_packet() to obtain
+     * input data.
+     */
+    int (*receive_frame)(struct AVCodecContext *avctx, struct AVFrame *frame);
+    /**
+     * Flush buffers.
+     * Will be called when seeking
+     */
+    void (*flush)(struct AVCodecContext *);
+
+    /**
+     * Decoding only, a comma-separated list of bitstream filters to apply to
+     * 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 *const *hw_configs;
+
+    /**
+     * List of supported codec_tags, terminated by FF_CODEC_TAGS_END.
+     */
+    const uint32_t *codec_tags;
+} FFCodec;
+
+static av_always_inline const FFCodec *ffcodec(const AVCodec *codec)
+{
+    return (const FFCodec*)codec;
+}
 
 #endif /* AVCODEC_CODEC_INTERNAL_H */