FFmpeg/libavcodec/mjpegenc.c

/*
 * MJPEG encoder
 * Copyright (c) 2000, 2001 Fabrice Bellard
 * Copyright (c) 2003 Alex Beregszaszi
 * Copyright (c) 2003-2004 Michael Niedermayer
 *
 * Support for external huffman table, various fixes (AVID workaround),
 * aspecting, new decode_frame mechanism and apple mjpeg-b support
 *                                  by Alex Beregszaszi
 *
 * This file is part of Libav.
 *
 * Libav 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.
 *
 * Libav 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 Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * MJPEG encoder.
 */

#include <assert.h>

#include "libavutil/pixdesc.h"

#include "avcodec.h"
#include "mjpegenc_common.h"
#include "mpegvideo.h"
#include "mjpeg.h"
#include "mjpegenc.h"

av_cold int ff_mjpeg_encode_init(MpegEncContext *s)
{
    MJpegContext *m;

    m = av_malloc(sizeof(MJpegContext));
    if (!m)
        return AVERROR(ENOMEM);

    s->min_qcoeff=-1023;
    s->max_qcoeff= 1023;

    /* build all the huffman tables */
    ff_mjpeg_build_huffman_codes(m->huff_size_dc_luminance,
                                 m->huff_code_dc_luminance,
                                 avpriv_mjpeg_bits_dc_luminance,
                                 avpriv_mjpeg_val_dc);
    ff_mjpeg_build_huffman_codes(m->huff_size_dc_chrominance,
                                 m->huff_code_dc_chrominance,
                                 avpriv_mjpeg_bits_dc_chrominance,
                                 avpriv_mjpeg_val_dc);
    ff_mjpeg_build_huffman_codes(m->huff_size_ac_luminance,
                                 m->huff_code_ac_luminance,
                                 avpriv_mjpeg_bits_ac_luminance,
                                 avpriv_mjpeg_val_ac_luminance);
    ff_mjpeg_build_huffman_codes(m->huff_size_ac_chrominance,
                                 m->huff_code_ac_chrominance,
                                 avpriv_mjpeg_bits_ac_chrominance,
                                 avpriv_mjpeg_val_ac_chrominance);

    s->mjpeg_ctx = m;
    return 0;
}

void ff_mjpeg_encode_close(MpegEncContext *s)
{
    av_free(s->mjpeg_ctx);
}

static void encode_block(MpegEncContext *s, int16_t *block, int n)
{
    int mant, nbits, code, i, j;
    int component, dc, run, last_index, val;
    MJpegContext *m = s->mjpeg_ctx;
    uint8_t *huff_size_ac;
    uint16_t *huff_code_ac;

    /* DC coef */
    component = (n <= 3 ? 0 : (n&1) + 1);
    dc = block[0]; /* overflow is impossible */
    val = dc - s->last_dc[component];
    if (n < 4) {
        ff_mjpeg_encode_dc(&s->pb, val, m->huff_size_dc_luminance, m->huff_code_dc_luminance);
        huff_size_ac = m->huff_size_ac_luminance;
        huff_code_ac = m->huff_code_ac_luminance;
    } else {
        ff_mjpeg_encode_dc(&s->pb, val, m->huff_size_dc_chrominance, m->huff_code_dc_chrominance);
        huff_size_ac = m->huff_size_ac_chrominance;
        huff_code_ac = m->huff_code_ac_chrominance;
    }
    s->last_dc[component] = dc;

    /* AC coefs */

    run = 0;
    last_index = s->block_last_index[n];
    for(i=1;i<=last_index;i++) {
        j = s->intra_scantable.permutated[i];
        val = block[j];
        if (val == 0) {
            run++;
        } else {
            while (run >= 16) {
                put_bits(&s->pb, huff_size_ac[0xf0], huff_code_ac[0xf0]);
                run -= 16;
            }
            mant = val;
            if (val < 0) {
                val = -val;
                mant--;
            }

            nbits= av_log2(val) + 1;
            code = (run << 4) | nbits;

            put_bits(&s->pb, huff_size_ac[code], huff_code_ac[code]);

            put_sbits(&s->pb, nbits, mant);
            run = 0;
        }
    }

    /* output EOB only if not already 64 values */
    if (last_index < 63 || run != 0)
        put_bits(&s->pb, huff_size_ac[0], huff_code_ac[0]);
}

void ff_mjpeg_encode_mb(MpegEncContext *s, int16_t block[6][64])
{
    int i;
    for(i=0;i<5;i++) {
        encode_block(s, block[i], i);
    }
    if (s->chroma_format == CHROMA_420) {
        encode_block(s, block[5], 5);
    } else {
        encode_block(s, block[6], 6);
        encode_block(s, block[5], 5);
        encode_block(s, block[7], 7);
    }

    s->i_tex_bits += get_bits_diff(s);
}

AVCodec ff_mjpeg_encoder = {
    .name           = "mjpeg",
    .long_name      = NULL_IF_CONFIG_SMALL("MJPEG (Motion JPEG)"),
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_MJPEG,
    .priv_data_size = sizeof(MpegEncContext),
    .init           = ff_mpv_encode_init,
    .encode2        = ff_mpv_encode_picture,
    .close          = ff_mpv_encode_end,
    .pix_fmts       = (const enum AVPixelFormat[]){
        AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P, AV_PIX_FMT_NONE
    },
};