davs2.c

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/*
 * AVS2 video stream probe.
 *
 * Copyright (C) 2018 Huiwen Ren, <hwrenx@126.com>
 *
 * 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
 */
 
#include "avformat.h"
#include "rawdec.h"
#include "libavcodec/internal.h"
#include "libavutil/intreadwrite.h"
 
#define ISSQH(x)  ((x) == 0xB0 )
#define ISEND(x)  ((x) == 0xB1 )
#define ISPIC(x)  ((x) == 0xB3 || (x) == 0xB6)
#define ISUNIT(x) ( ISSQH(x) || ISEND(x) || (x) == 0xB2 || ISPIC(x) || (x) == 0xB5 || (x) == 0xB7 )
#define ISAVS2(x) ((x) == 0x20 || (x) == 0x22 || (x) == 0x30 || (x) == 0x32 )
 
static int avs2_probe(const AVProbeData *p)
{
    uint32_t code= -1, hds=0, pic=0, seq=0;
    uint8_t state=0;
    const uint8_t *ptr = p->buf, *end = p->buf + p->buf_size, *sqb=0;
    if (AV_RB32(p->buf) != 0x1B0){
        return 0;
    }
 
    while (ptr < end) {
        ptr = avpriv_find_start_code(ptr, end, &code);
        state = code & 0xFF;
        if ((code & 0xffffff00) == 0x100) {
            if (ISUNIT(state)) {
                if (sqb && !hds) {
                    hds = ptr - sqb;
                }
                if (ISSQH(state)) {
                    if (!ISAVS2(*ptr))
                        return 0;
                    sqb = ptr;
                    seq++;
                } else if (ISPIC(state)) {
                    pic++;
                } else if (ISEND(state)) {
                    break;
                }
            }
        }
    }
    if (seq && hds >= 21 && pic){
        return AVPROBE_SCORE_EXTENSION + 2; // more than cavs
    }
 
    return 0;
}
 
FF_DEF_RAWVIDEO_DEMUXER(avs2, "raw AVS2-P2/IEEE1857.4", avs2_probe, "avs,avs2", AV_CODEC_ID_AVS2)