FFmpeg/libavcodec/rv34_parser.c

/*
 * RV30/40 parser
 * Copyright (c) 2011 Konstantin Shishkov
 *
 * 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
 * RV30/40 parser
 */

#include "avcodec.h"
#include "libavutil/intreadwrite.h"

typedef struct RV34ParseContext {
    int64_t key_dts;
    int key_pts;
} RV34ParseContext;

static const int rv_to_av_frame_type[4] = {
    AV_PICTURE_TYPE_I, AV_PICTURE_TYPE_I, AV_PICTURE_TYPE_P, AV_PICTURE_TYPE_B,
};

static int rv34_parse(AVCodecParserContext *s,
                      AVCodecContext *avctx,
                      const uint8_t **poutbuf, int *poutbuf_size,
                      const uint8_t *buf, int buf_size)
{
    RV34ParseContext *pc = s->priv_data;
    int type, pts, hdr;

    if (buf_size < 13 + *buf * 8) {
        *poutbuf = buf;
        *poutbuf_size = buf_size;
        return buf_size;
    }

    hdr = AV_RB32(buf + 9 + *buf * 8);
    if (avctx->codec_id == AV_CODEC_ID_RV30) {
        type = (hdr >> 27) & 3;
        pts  = (hdr >>  7) & 0x1FFF;
    } else {
        type = (hdr >> 29) & 3;
        pts  = (hdr >>  6) & 0x1FFF;
    }

    if (type != 3 && s->pts != AV_NOPTS_VALUE) {
        pc->key_dts = s->pts;
        pc->key_pts = pts;
    } else {
        if (type != 3)
            s->pts = pc->key_dts + ((pts - pc->key_pts) & 0x1FFF);
        else
            s->pts = pc->key_dts - ((pc->key_pts - pts) & 0x1FFF);
    }
    s->pict_type = rv_to_av_frame_type[type];

    *poutbuf = buf;
    *poutbuf_size = buf_size;
    return buf_size;
}

const AVCodecParser ff_rv34_parser = {
    .codec_ids      = { AV_CODEC_ID_RV30, AV_CODEC_ID_RV40 },
    .priv_data_size = sizeof(RV34ParseContext),
    .parser_parse   = rv34_parse,
};