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/* |
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* PNG parser |
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* Copyright (c) 2009 Peter Holik |
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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 |
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* PNG parser |
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*/ |
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#include "parser.h" |
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#include "png.h" |
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typedef struct PNGParseContext { |
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ParseContext pc; |
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uint32_t chunk_pos; ///< position inside current chunk |
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uint32_t chunk_length; ///< length of the current chunk |
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uint32_t remaining_size; ///< remaining size of the current chunk |
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} PNGParseContext; |
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static int png_parse(AVCodecParserContext *s, 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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PNGParseContext *ppc = s->priv_data; |
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int next = END_NOT_FOUND; |
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int i = 0; |
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s->pict_type = AV_PICTURE_TYPE_NONE; |
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*poutbuf_size = 0; |
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✓✓ |
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if (!ppc->pc.frame_start_found) { |
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uint64_t state64 = ppc->pc.state64; |
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✓✓ |
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for (; i < buf_size; i++) { |
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state64 = (state64 << 8) | buf[i]; |
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✓✓✗✓
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if (state64 == PNGSIG || state64 == MNGSIG) { |
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i++; |
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ppc->pc.frame_start_found = 1; |
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break; |
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} |
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} |
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ppc->pc.state64 = state64; |
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✓✗ |
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} else if (ppc->remaining_size) { |
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i = FFMIN(ppc->remaining_size, buf_size); |
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ppc->remaining_size -= i; |
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✓✓ |
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if (ppc->remaining_size) |
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goto flush; |
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✗✓ |
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if (ppc->chunk_pos == -1) { |
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next = i; |
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goto flush; |
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} |
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} |
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✓✓✓✗
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for (; ppc->pc.frame_start_found && i < buf_size; i++) { |
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ppc->pc.state = (ppc->pc.state << 8) | buf[i]; |
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✓✓ |
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if (ppc->chunk_pos == 3) { |
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ppc->chunk_length = ppc->pc.state; |
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✗✓ |
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if (ppc->chunk_length > 0x7fffffff) { |
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ppc->chunk_pos = ppc->pc.frame_start_found = 0; |
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goto flush; |
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} |
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ppc->chunk_length += 4; |
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✓✓ |
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} else if (ppc->chunk_pos == 7) { |
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✓✓ |
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if (ppc->chunk_length >= buf_size - i) |
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ppc->remaining_size = ppc->chunk_length - buf_size + i + 1; |
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✓✓ |
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if (ppc->pc.state == MKBETAG('I', 'E', 'N', 'D')) { |
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✗✓ |
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if (ppc->remaining_size) |
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ppc->chunk_pos = -1; |
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else |
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next = ppc->chunk_length + i + 1; |
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break; |
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} else { |
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ppc->chunk_pos = 0; |
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✓✓ |
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if (ppc->remaining_size) |
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break; |
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else |
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i += ppc->chunk_length; |
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continue; |
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} |
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} |
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ppc->chunk_pos++; |
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} |
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flush: |
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✓✓ |
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if (ff_combine_frame(&ppc->pc, next, &buf, &buf_size) < 0) |
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return buf_size; |
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ppc->chunk_pos = ppc->pc.frame_start_found = 0; |
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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 ff_png_parser = { |
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.codec_ids = { AV_CODEC_ID_PNG }, |
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.priv_data_size = sizeof(PNGParseContext), |
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.parser_parse = png_parse, |
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.parser_close = ff_parse_close, |
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}; |