mirror of
https://github.com/FFmpeg/FFmpeg.git
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127 lines
3.6 KiB
C
127 lines
3.6 KiB
C
/*
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* DCA parser
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* Copyright (C) 2004 Gildas Bazin
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* Copyright (C) 2004 Benjamin Zores
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* Copyright (C) 2006 Benjamin Larsson
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* Copyright (C) 2007 Konstantin Shishkov
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file dca_parser.c
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*/
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#include "parser.h"
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#include "dca.h"
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typedef struct DCAParseContext {
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ParseContext pc;
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uint32_t lastmarker;
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} DCAParseContext;
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#define IS_MARKER(state, i, buf, buf_size) \
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((state == DCA_MARKER_14B_LE && (i < buf_size-2) && (buf[i+1] & 0xF0) == 0xF0 && buf[i+2] == 0x07) \
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|| (state == DCA_MARKER_14B_BE && (i < buf_size-2) && buf[i+1] == 0x07 && (buf[i+2] & 0xF0) == 0xF0) \
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|| state == DCA_MARKER_RAW_LE || state == DCA_MARKER_RAW_BE)
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/**
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* finds the end of the current frame in the bitstream.
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* @return the position of the first byte of the next frame, or -1
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*/
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static int dca_find_frame_end(DCAParseContext * pc1, const uint8_t * buf,
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int buf_size)
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{
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int start_found, i;
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uint32_t state;
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ParseContext *pc = &pc1->pc;
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start_found = pc->frame_start_found;
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state = pc->state;
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i = 0;
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if (!start_found) {
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for (i = 0; i < buf_size; i++) {
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state = (state << 8) | buf[i];
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if (IS_MARKER(state, i, buf, buf_size)) {
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if (pc1->lastmarker && state == pc1->lastmarker) {
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start_found = 1;
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break;
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} else if (!pc1->lastmarker) {
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start_found = 1;
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pc1->lastmarker = state;
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break;
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}
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}
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}
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}
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if (start_found) {
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for (; i < buf_size; i++) {
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state = (state << 8) | buf[i];
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if (state == pc1->lastmarker && IS_MARKER(state, i, buf, buf_size)) {
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pc->frame_start_found = 0;
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pc->state = -1;
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return i - 3;
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}
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}
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}
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pc->frame_start_found = start_found;
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pc->state = state;
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return END_NOT_FOUND;
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}
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static av_cold int dca_parse_init(AVCodecParserContext * s)
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{
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DCAParseContext *pc1 = s->priv_data;
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pc1->lastmarker = 0;
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return 0;
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}
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static int dca_parse(AVCodecParserContext * s,
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AVCodecContext * avctx,
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const uint8_t ** poutbuf, int *poutbuf_size,
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const uint8_t * buf, int buf_size)
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{
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DCAParseContext *pc1 = s->priv_data;
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ParseContext *pc = &pc1->pc;
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int next;
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if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
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next = buf_size;
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} else {
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next = dca_find_frame_end(pc1, 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;
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return buf_size;
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}
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}
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*poutbuf = buf;
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*poutbuf_size = buf_size;
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return next;
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}
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AVCodecParser dca_parser = {
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{CODEC_ID_DTS},
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sizeof(DCAParseContext),
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dca_parse_init,
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dca_parse,
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ff_parse_close,
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};
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