FFmpeg/libavcodec/avdct.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_AVDCT_H
#define AVCODEC_AVDCT_H

#include "libavutil/opt.h"

/**
 * AVDCT context.
 * @note function pointers can be NULL if the specific features have been
 *       disabled at build time.
 */
typedef struct AVDCT {
    const AVClass *av_class;

    void (*idct)(int16_t *block /* align 16 */);

    /**
     * IDCT input permutation.
     * Several optimized IDCTs need a permutated input (relative to the
     * normal order of the reference IDCT).
     * This permutation must be performed before the idct_put/add.
     * Note, normally this can be merged with the zigzag/alternate scan<br>
     * An example to avoid confusion:
     * - (->decode coeffs -> zigzag reorder -> dequant -> reference IDCT -> ...)
     * - (x -> reference DCT -> reference IDCT -> x)
     * - (x -> reference DCT -> simple_mmx_perm = idct_permutation
     *    -> simple_idct_mmx -> x)
     * - (-> decode coeffs -> zigzag reorder -> simple_mmx_perm -> dequant
     *    -> simple_idct_mmx -> ...)
     */
    uint8_t idct_permutation[64];

    void (*fdct)(int16_t *block /* align 16 */);


    /**
     * DCT algorithm.
     * must use AVOptions to set this field.
     */
    int dct_algo;

    /**
     * IDCT algorithm.
     * must use AVOptions to set this field.
     */
    int idct_algo;

    void (*get_pixels)(int16_t *block /* align 16 */,
                       const uint8_t *pixels /* align 8 */,
                       ptrdiff_t line_size);
} AVDCT;

/**
 * Allocates a AVDCT context.
 * This needs to be initialized with avcodec_dct_init() after optionally
 * configuring it with AVOptions.
 *
 * To free it use av_free()
 */
AVDCT *avcodec_dct_alloc(void);
int avcodec_dct_init(AVDCT *);

const AVClass *avcodec_dct_get_class(void);

#endif /* AVCODEC_AVDCT_H */