jpegls.h 3.11 KB
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/*
 * JPEG-LS common code
 * Copyright (c) 2003 Michael Niedermayer
 * Copyright (c) 2006 Konstantin Shishkov
 *
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * 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.
 *
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 * Libav is distributed in the hope that it will be useful,
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 * 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
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
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 * @file
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 * JPEG-LS common code.
 */

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#ifndef AVCODEC_JPEGLS_H
#define AVCODEC_JPEGLS_H
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#include "libavutil/common.h"
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#include "avcodec.h"
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typedef struct JpeglsContext {
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    AVCodecContext *avctx;
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} JpeglsContext;
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typedef struct JLSState {
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    int T1, T2, T3;
    int A[367], B[367], C[365], N[367];
    int limit, reset, bpp, qbpp, maxval, range;
    int near, twonear;
    int run_index[3];
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} JLSState;
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extern const uint8_t ff_log2_run[32];

/**
 * Calculate initial JPEG-LS parameters
 */
void ff_jpegls_init_state(JLSState *state);

/**
 * Calculate quantized gradient value, used for context determination
 */
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static inline int ff_jpegls_quantize(JLSState *s, int v)
{
    if (v == 0)
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        return 0;
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    if (v < 0) {
        if (v <= -s->T3)
            return -4;
        if (v <= -s->T2)
            return -3;
        if (v <= -s->T1)
            return -2;
        if (v < -s->near)
            return -1;
        return 0;
    } else {
        if (v <= s->near)
            return 0;
        if (v < s->T1)
            return 1;
        if (v < s->T2)
            return 2;
        if (v < s->T3)
            return 3;
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        return 4;
    }
}

/**
 * Calculate JPEG-LS codec values
 */
void ff_jpegls_reset_coding_parameters(JLSState *s, int reset_all);

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static inline void ff_jpegls_downscale_state(JLSState *state, int Q)
{
    if (state->N[Q] == state->reset) {
        state->A[Q] >>= 1;
        state->B[Q] >>= 1;
        state->N[Q] >>= 1;
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    }
    state->N[Q]++;
}

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static inline int ff_jpegls_update_state_regular(JLSState *state,
                                                 int Q, int err)
{
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    state->A[Q] += FFABS(err);
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    err         *= state->twonear;
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    state->B[Q] += err;

    ff_jpegls_downscale_state(state, Q);

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    if (state->B[Q] <= -state->N[Q]) {
        state->B[Q] = FFMAX(state->B[Q] + state->N[Q], 1 - state->N[Q]);
        if (state->C[Q] > -128)
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            state->C[Q]--;
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    } else if (state->B[Q] > 0) {
        state->B[Q] = FFMIN(state->B[Q] - state->N[Q], 0);
        if (state->C[Q] < 127)
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            state->C[Q]++;
    }

    return err;
}

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#define R(a, i)    (bits == 8 ?  ((uint8_t *)(a))[i]      :  ((uint16_t *)(a))[i])
#define W(a, i, v) (bits == 8 ? (((uint8_t *)(a))[i] = v) : (((uint16_t *)(a))[i] = v))
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#endif /* AVCODEC_JPEGLS_H */