ffmpeg/libavcodec/cljrenc.c

/*
 * Cirrus Logic AccuPak (CLJR) encoder
 * Copyright (c) 2003 Alex Beregszaszi
 *
 * 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
 */

/**
 * @file
 * Cirrus Logic AccuPak encoder.
 */

#include "libavutil/opt.h"

#include "avcodec.h"
#include "codec_internal.h"
#include "encode.h"
#include "put_bits.h"

typedef struct CLJRContext {
    AVClass        *avclass;
    int             dither_type;
} CLJRContext;

static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
                        const AVFrame *p, int *got_packet)
{
    CLJRContext *a = avctx->priv_data;
    PutBitContext pb;
    int x, y, ret;
    uint32_t dither= avctx->frame_num;
    static const uint32_t ordered_dither[2][2] =
    {
        { 0x10400000, 0x104F0000 },
        { 0xCB2A0000, 0xCB250000 },
    };

    if (avctx->width%4 && avctx->strict_std_compliance > FF_COMPLIANCE_UNOFFICIAL) {
         av_log(avctx, AV_LOG_ERROR,
                "Widths which are not a multiple of 4 might fail with some decoders, "
                "use vstrict=-1 / -strict -1 to use %d anyway.\n", avctx->width);
         return AVERROR_EXPERIMENTAL;
    }

    ret = ff_get_encode_buffer(avctx, pkt, 4 * avctx->height * ((avctx->width + 3) / 4), 0);
    if (ret < 0)
        return ret;

    init_put_bits(&pb, pkt->data, pkt->size);

    for (y = 0; y < avctx->height; y++) {
        const uint8_t *luma = &p->data[0][y * p->linesize[0]];
        const uint8_t *cb   = &p->data[1][y * p->linesize[1]];
        const uint8_t *cr   = &p->data[2][y * p->linesize[2]];
        uint8_t luma_tmp[4];
        for (x = 0; x < avctx->width; x += 4) {
            switch (a->dither_type) {
            case 0: dither = 0x492A0000;                       break;
            case 1: dither = dither * 1664525 + 1013904223;    break;
            case 2: dither = ordered_dither[ y&1 ][ (x>>2)&1 ];break;
            }
            if (x+3 >= avctx->width) {
                memset(luma_tmp, 0, sizeof(luma_tmp));
                memcpy(luma_tmp, luma, avctx->width - x);
                luma = luma_tmp;
            }
            put_bits(&pb, 5, (249*(luma[3] +  (dither>>29)   )) >> 11);
            put_bits(&pb, 5, (249*(luma[2] + ((dither>>26)&7))) >> 11);
            put_bits(&pb, 5, (249*(luma[1] + ((dither>>23)&7))) >> 11);
            put_bits(&pb, 5, (249*(luma[0] + ((dither>>20)&7))) >> 11);
            luma += 4;
            put_bits(&pb, 6, (253*(*(cb++) + ((dither>>18)&3))) >> 10);
            put_bits(&pb, 6, (253*(*(cr++) + ((dither>>16)&3))) >> 10);
        }
    }

    flush_put_bits(&pb);

    *got_packet = 1;
    return 0;
}

#define OFFSET(x) offsetof(CLJRContext, x)
#define VE AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
static const AVOption options[] = {
    { "dither_type",   "Dither type",   OFFSET(dither_type),        AV_OPT_TYPE_INT, { .i64=1 }, 0, 2, VE},
    { NULL },
};

static const AVClass cljr_class = {
    .class_name = "cljr encoder",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
};

const FFCodec ff_cljr_encoder = {
    .p.name         = "cljr",
    CODEC_LONG_NAME("Cirrus Logic AccuPak"),
    .p.type         = AVMEDIA_TYPE_VIDEO,
    .p.id           = AV_CODEC_ID_CLJR,
    .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE,
    .priv_data_size = sizeof(CLJRContext),
    FF_CODEC_ENCODE_CB(encode_frame),
    .p.pix_fmts     = (const enum AVPixelFormat[]) { AV_PIX_FMT_YUV411P,
                                                   AV_PIX_FMT_NONE },
    .p.priv_class   = &cljr_class,
};