FFmpeg/libavcodec/codec_internal.h

/*
 * 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
 */

#ifndef AVCODEC_CODEC_INTERNAL_H
#define AVCODEC_CODEC_INTERNAL_H

#include <stdint.h>

#include "libavutil/attributes.h"
#include "codec.h"

/**
 * The codec is not known to be init-threadsafe (i.e. it might be unsafe
 * to initialize this codec and another codec concurrently, typically because
 * the codec calls external APIs that are not known to be thread-safe).
 * Therefore calling the codec's init function needs to be guarded with a lock.
 */
#define FF_CODEC_CAP_NOT_INIT_THREADSAFE    (1 << 0)
/**
 * The codec allows calling the close function for deallocation even if
 * the init function returned a failure. Without this capability flag, a
 * codec does such cleanup internally when returning failures from the
 * init function and does not expect the close function to be called at
 * all.
 */
#define FF_CODEC_CAP_INIT_CLEANUP           (1 << 1)
/**
 * Decoders marked with FF_CODEC_CAP_SETS_PKT_DTS want to set
 * AVFrame.pkt_dts manually. If the flag is set, decode.c won't overwrite
 * this field. If it's unset, decode.c tries to guess the pkt_dts field
 * from the input AVPacket.
 */
#define FF_CODEC_CAP_SETS_PKT_DTS           (1 << 2)
/**
 * The decoder extracts and fills its parameters even if the frame is
 * skipped due to the skip_frame setting.
 */
#define FF_CODEC_CAP_SKIP_FRAME_FILL_PARAM  (1 << 3)
/**
 * The decoder sets the cropping fields in the output frames manually.
 * If this cap is set, the generic code will initialize output frame
 * dimensions to coded rather than display values.
 */
#define FF_CODEC_CAP_EXPORTS_CROPPING       (1 << 4)
/**
 * Codec initializes slice-based threading with a main function
 */
#define FF_CODEC_CAP_SLICE_THREAD_HAS_MF    (1 << 5)
/*
 * The codec supports frame threading and has inter-frame dependencies, so it
 * uses ff_thread_report/await_progress().
 */
#define FF_CODEC_CAP_ALLOCATE_PROGRESS      (1 << 6)
/**
 * Codec handles avctx->thread_count == 0 (auto) internally.
 */
#define FF_CODEC_CAP_AUTO_THREADS           (1 << 7)
/**
 * Codec handles output frame properties internally instead of letting the
 * internal logic derive them from AVCodecInternal.last_pkt_props.
 */
#define FF_CODEC_CAP_SETS_FRAME_PROPS       (1 << 8)

/**
 * FFCodec.codec_tags termination value
 */
#define FF_CODEC_TAGS_END -1

typedef struct FFCodecDefault {
    const char *key;
    const char *value;
} FFCodecDefault;

struct AVCodecContext;
struct AVSubtitle;
struct AVPacket;

enum FFCodecType {
    /* The codec is a decoder using the decode callback;
     * audio and video codecs only. */
    FF_CODEC_CB_TYPE_DECODE,
    /* The codec is a decoder using the decode_sub callback;
     * subtitle codecs only. */
    FF_CODEC_CB_TYPE_DECODE_SUB,
    /* The codec is a decoder using the receive_frame callback;
     * audio and video codecs only. */
    FF_CODEC_CB_TYPE_RECEIVE_FRAME,
    /* The codec is an encoder using the encode callback;
     * audio and video codecs only. */
    FF_CODEC_CB_TYPE_ENCODE,
    /* The codec is an encoder using the encode_sub callback;
     * subtitle codecs only. */
    FF_CODEC_CB_TYPE_ENCODE_SUB,
    /* The codec is an encoder using the receive_packet callback;
     * audio and video codecs only. */
    FF_CODEC_CB_TYPE_RECEIVE_PACKET,
};

typedef struct FFCodec {
    /**
     * The public AVCodec. See codec.h for it.
     */
    AVCodec p;

    /**
     * Internal codec capabilities FF_CODEC_CAP_*.
     */
    unsigned caps_internal:29;

    /**
     * This field determines the type of the codec (decoder/encoder)
     * and also the exact callback cb implemented by the codec.
     * cb_type uses enum FFCodecType values.
     */
    unsigned cb_type:3;

    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 FFCodecDefault *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 *);

    union {
        /**
         * Decode to an AVFrame.
         * cb is in this state if cb_type is FF_CODEC_CB_TYPE_DECODE.
         *
         * @param      avctx          codec context
         * @param[out] frame          AVFrame for output
         * @param[out] got_frame_ptr  decoder sets to 0 or 1 to indicate that
         *                            a non-empty frame was returned in frame.
         * @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, struct AVFrame *frame,
                      int *got_frame_ptr, struct AVPacket *avpkt);
        /**
         * Decode subtitle data to an AVSubtitle.
         * cb is in this state if cb_type is FF_CODEC_CB_TYPE_DECODE_SUB.
         *
         * Apart from that this is like the decode callback.
         */
        int (*decode_sub)(struct AVCodecContext *avctx, struct AVSubtitle *sub,
                          int *got_frame_ptr, const struct AVPacket *avpkt);
        /**
         * Decode API with decoupled packet/frame dataflow.
         * cb is in this state if cb_type is FF_CODEC_CB_TYPE_RECEIVE_FRAME.
         *
         * 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);
        /**
         * Encode data to an AVPacket.
         * cb is in this state if cb_type is FF_CODEC_CB_TYPE_ENCODE
         *
         * @param      avctx          codec context
         * @param[out] avpkt          output AVPacket
         * @param[in]  frame          AVFrame containing the input 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 (*encode)(struct AVCodecContext *avctx, struct AVPacket *avpkt,
                      const struct AVFrame *frame, int *got_packet_ptr);
        /**
         * Encode subtitles to a raw buffer.
         * cb is in this state if cb_type is FF_CODEC_CB_TYPE_ENCODE_SUB.
         */
        int (*encode_sub)(struct AVCodecContext *avctx, uint8_t *buf,
                          int buf_size, const struct AVSubtitle *sub);
        /**
         * Encode API with decoupled frame/packet dataflow.
         * cb is in this state if cb_type is FF_CODEC_CB_TYPE_RECEIVE_PACKET.
         *
         * 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);
    } cb;

    int (*close)(struct AVCodecContext *);

    /**
     * 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;

#define FF_CODEC_DECODE_CB(func)                          \
    .cb_type           = FF_CODEC_CB_TYPE_DECODE,         \
    .cb.decode         = (func)
#define FF_CODEC_DECODE_SUB_CB(func)                      \
    .cb_type           = FF_CODEC_CB_TYPE_DECODE_SUB,     \
    .cb.decode_sub     = (func)
#define FF_CODEC_RECEIVE_FRAME_CB(func)                   \
    .cb_type           = FF_CODEC_CB_TYPE_RECEIVE_FRAME,  \
    .cb.receive_frame  = (func)
#define FF_CODEC_ENCODE_CB(func)                          \
    .cb_type           = FF_CODEC_CB_TYPE_ENCODE,         \
    .cb.encode         = (func)
#define FF_CODEC_ENCODE_SUB_CB(func)                      \
    .cb_type           = FF_CODEC_CB_TYPE_ENCODE_SUB,     \
    .cb.encode_sub     = (func)
#define FF_CODEC_RECEIVE_PACKET_CB(func)                  \
    .cb_type           = FF_CODEC_CB_TYPE_RECEIVE_PACKET, \
    .cb.receive_packet = (func)

static av_always_inline const FFCodec *ffcodec(const AVCodec *codec)
{
    return (const FFCodec*)codec;
}

#endif /* AVCODEC_CODEC_INTERNAL_H */