/*

 * MPEG-4 video frame extraction

 * Copyright (c) 2003 Fabrice Bellard

 * Copyright (c) 2003 Michael Niedermayer

 *

 * 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

 */

#define UNCHECKED_BITSTREAM_READER 1

#include "decode.h"

#include "parser.h"

#include "mpegvideo.h"

#include "mpeg4videodec.h"

#include "mpeg4videodefs.h"

#include "parser_internal.h"

struct Mp4vParseContext {

    ParseContext pc;

    Mpeg4DecContext dec_ctx;

    int first_picture;

};

/**

 * Find the end of the current frame in the bitstream.

 * @return the position of the first byte of the next frame, or -1

 */

static int mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)

{

    int vop_found, i;

    uint32_t state;

    vop_found = pc->frame_start_found;

    state     = pc->state;

    i = 0;

    if (!vop_found) {

        for (i = 0; i < buf_size; i++) {

            state = (state << 8) | buf[i];

            if (state == VOP_STARTCODE) {

                i++;

                vop_found = 1;

                break;

            }

        }

    }

    if (vop_found) {

        /* EOF considered as end of frame */

        if (buf_size == 0)

            return 0;

        for (; i < buf_size; i++) {

            state = (state << 8) | buf[i];

            if ((state & 0xFFFFFF00) == 0x100) {

                if (state == SLICE_STARTCODE || state == EXT_STARTCODE)

                    continue;

                pc->frame_start_found = 0;

                pc->state             = -1;

                return i - 3;

            }

        }

    }

    pc->frame_start_found = vop_found;

    pc->state             = state;

    return END_NOT_FOUND;

}

/* XXX: make it use less memory */

static int mpeg4_decode_header(AVCodecParserContext *s1, AVCodecContext *avctx,

                               const uint8_t *buf, int buf_size)

{

    struct Mp4vParseContext *pc = s1->priv_data;

    Mpeg4DecContext *dec_ctx = &pc->dec_ctx;

    MPVContext *const s = &dec_ctx->h.c;

    GetBitContext gb1, *gb = &gb1;

    int ret;

    s->avctx               = avctx;

    if (avctx->extradata_size && pc->first_picture) {

        init_get_bits(gb, avctx->extradata, avctx->extradata_size * 8);

        ret = ff_mpeg4_parse_picture_header(dec_ctx, gb, 1, 1);

        if (ret < 0)

            av_log(avctx, AV_LOG_WARNING, "Failed to parse extradata\n");

    }

    init_get_bits(gb, buf, 8 * buf_size);

    ret = ff_mpeg4_parse_picture_header(dec_ctx, gb, 0, 1);

    avctx->has_b_frames = !s->low_delay;

    if (s->width && (!avctx->width || !avctx->height ||

                     !avctx->coded_width || !avctx->coded_height)) {

        ret = ff_set_dimensions(avctx, s->width, s->height);

        if (ret < 0)

            return ret;

    }

    if((s1->flags & PARSER_FLAG_USE_CODEC_TS) && s->avctx->framerate.num>0 && ret>=0){

        av_assert1(s1->pts == AV_NOPTS_VALUE);

        av_assert1(s1->dts == AV_NOPTS_VALUE);

        s1->pts = av_rescale_q(s->time, (AVRational){1, s->avctx->framerate.num}, (AVRational){1, 1200000});

    }

    s1->pict_type     = s->pict_type;

    pc->first_picture = 0;

    return ret;

}

static av_cold int mpeg4video_parse_init(AVCodecParserContext *s)

{

    struct Mp4vParseContext *pc = s->priv_data;

    pc->first_picture           = 1;

    pc->dec_ctx.quant_precision       = 5;

    pc->dec_ctx.h.c.slice_context_count = 1;

    pc->dec_ctx.showed_packed_warning = 1;

    return 0;

}

static int mpeg4video_parse(AVCodecParserContext *s,

                            AVCodecContext *avctx,

                            const uint8_t **poutbuf, int *poutbuf_size,

                            const uint8_t *buf, int buf_size)

{

    ParseContext *pc = s->priv_data;

    int next;

    if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {

        next = buf_size;

    } else {

        next = mpeg4_find_frame_end(pc, buf, buf_size);

        if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {

            *poutbuf      = NULL;

            *poutbuf_size = 0;

            return buf_size;

        }

    }

    mpeg4_decode_header(s, avctx, buf, buf_size);

    *poutbuf      = buf;

    *poutbuf_size = buf_size;

    return next;

}

const FFCodecParser ff_mpeg4video_parser = {

    PARSER_CODEC_LIST(AV_CODEC_ID_MPEG4),

    .priv_data_size = sizeof(struct Mp4vParseContext),

    .init           = mpeg4video_parse_init,

    .parse          = mpeg4video_parse,

    .close          = ff_parse_close,

};