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/*
* MPEG4 Video frame extraction |
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* Copyright (c) 2003 Fabrice Bellard
* Copyright (c) 2003 Michael Niedermayer |
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*
* 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
*/
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#define UNCHECKED_BITSTREAM_READER 1
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#include "internal.h" |
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#include "parser.h"
#include "mpegvideo.h" |
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#include "mpeg4video.h" |
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#include "mpeg4video_parser.h" |
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struct Mp4vParseContext {
ParseContext pc; |
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Mpeg4DecContext dec_ctx; |
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int first_picture;
}; |
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|
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int ff_mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
{ |
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int vop_found, i;
uint32_t state;
|
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vop_found = pc->frame_start_found;
state = pc->state; |
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|
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i = 0;
if (!vop_found) {
for (i = 0; i < buf_size; i++) {
state = (state << 8) | buf[i];
if (state == 0x1B6) { |
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i++; |
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vop_found = 1; |
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break;
}
}
}
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if (vop_found) { |
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/* EOF considered as end of frame */
if (buf_size == 0)
return 0; |
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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; |
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}
}
} |
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pc->frame_start_found = vop_found;
pc->state = state; |
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return END_NOT_FOUND;
}
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/* XXX: make it use less memory */ |
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static int mpeg4_decode_header(AVCodecParserContext *s1, AVCodecContext *avctx,
const uint8_t *buf, int buf_size) |
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{ |
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struct Mp4vParseContext *pc = s1->priv_data; |
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Mpeg4DecContext *dec_ctx = &pc->dec_ctx;
MpegEncContext *s = &dec_ctx->m; |
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GetBitContext gb1, *gb = &gb1;
int ret;
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s->avctx = avctx; |
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s->current_picture_ptr = &s->current_picture;
|
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if (avctx->extradata_size && pc->first_picture) {
init_get_bits(gb, avctx->extradata, avctx->extradata_size * 8); |
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ret = ff_mpeg4_decode_picture_header(dec_ctx, gb); |
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}
init_get_bits(gb, buf, 8 * buf_size); |
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ret = ff_mpeg4_decode_picture_header(dec_ctx, gb); |
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if (s->width && (!avctx->width || !avctx->height ||
!avctx->coded_width || !avctx->coded_height)) { |
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ret = ff_set_dimensions(avctx, s->width, s->height);
if (ret < 0)
return ret; |
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} |
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if((s1->flags & PARSER_FLAG_USE_CODEC_TS) && s->avctx->time_base.den>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->time_base.den}, (AVRational){1, 1200000});
}
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s1->pict_type = s->pict_type; |
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pc->first_picture = 0;
return ret;
}
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static av_cold int mpeg4video_parse_init(AVCodecParserContext *s) |
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{ |
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struct Mp4vParseContext *pc = s->priv_data; |
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ff_mpeg4videodec_static_init();
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pc->first_picture = 1; |
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pc->dec_ctx.m.quant_precision = 5; |
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pc->dec_ctx.m.slice_context_count = 1; |
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pc->dec_ctx.showed_packed_warning = 1; |
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return 0;
}
static int mpeg4video_parse(AVCodecParserContext *s, |
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AVCodecContext *avctx,
const uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size) |
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{
ParseContext *pc = s->priv_data;
int next;
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if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
next = buf_size;
} else {
next = ff_mpeg4_find_frame_end(pc, buf, buf_size); |
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if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { |
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*poutbuf = NULL; |
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*poutbuf_size = 0;
return buf_size;
}
} |
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mpeg4_decode_header(s, avctx, buf, buf_size); |
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*poutbuf = buf; |
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*poutbuf_size = buf_size;
return next;
}
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AVCodecParser ff_mpeg4video_parser = { |
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.codec_ids = { AV_CODEC_ID_MPEG4 }, |
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.priv_data_size = sizeof(struct Mp4vParseContext), |
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.parser_init = mpeg4video_parse_init,
.parser_parse = mpeg4video_parse, |
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.parser_close = ff_parse_close, |
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.split = ff_mpeg4video_split, |
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}; |