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/*
* MPEG4 Video frame extraction
* Copyright (c) 2003 Fabrice Bellard
* Copyright (c) 2003 Michael Niedermayer
*
* 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
*/
#include "internal.h"
#include "parser.h"
#include "mpegvideo.h"
#include "mpeg4video.h"
#include "mpeg4video_parser.h"
struct Mp4vParseContext {
ParseContext pc;
Mpeg4DecContext dec_ctx;
int first_picture;
};
int ff_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 == 0x1B6) {
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) {
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;
MpegEncContext *s = &dec_ctx->m;
GetBitContext gb1, *gb = &gb1;
int ret;
s->avctx = avctx;
s->current_picture_ptr = &s->current_picture;
if (avctx->extradata_size && pc->first_picture) {
init_get_bits(gb, avctx->extradata, avctx->extradata_size * 8);
ret = ff_mpeg4_decode_picture_header(dec_ctx, gb);
}
init_get_bits(gb, buf, 8 * buf_size);
ret = ff_mpeg4_decode_picture_header(dec_ctx, gb);
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;
}
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.m.slice_context_count = 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 = ff_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;
}
AVCodecParser ff_mpeg4video_parser = {
.codec_ids = { AV_CODEC_ID_MPEG4 },
.priv_data_size = sizeof(struct Mp4vParseContext),
.parser_init = mpeg4video_parse_init,
.parser_parse = mpeg4video_parse,
.parser_close = ff_parse_close,
.split = ff_mpeg4video_split,
};
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