yading@10: /*
yading@10:  * PNG parser
yading@10:  * Copyright (c) 2009 Peter Holik
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: /**
yading@10:  * @file
yading@10:  * PNG parser
yading@10:  */
yading@10: 
yading@10: #include "parser.h"
yading@10: #include "png.h"
yading@10: 
yading@10: typedef struct PNGParseContext
yading@10: {
yading@10:     ParseContext pc;
yading@10:     uint32_t index;
yading@10:     uint32_t chunk_length;
yading@10:     uint32_t remaining_size;
yading@10: } PNGParseContext;
yading@10: 
yading@10: static int png_parse(AVCodecParserContext *s, AVCodecContext *avctx,
yading@10:                      const uint8_t **poutbuf, int *poutbuf_size,
yading@10:                      const uint8_t *buf, int buf_size)
yading@10: {
yading@10:     PNGParseContext *ppc = s->priv_data;
yading@10:     int next = END_NOT_FOUND;
yading@10:     int i = 0;
yading@10: 
yading@10:     s->pict_type = AV_PICTURE_TYPE_NONE;
yading@10: 
yading@10:     *poutbuf_size = 0;
yading@10:     if (buf_size == 0)
yading@10:         return 0;
yading@10: 
yading@10:     if (!ppc->pc.frame_start_found) {
yading@10:         uint64_t state64 = ppc->pc.state64;
yading@10:         for (; i < buf_size; i++) {
yading@10:             state64 = (state64 << 8) | buf[i];
yading@10:             if (state64 == PNGSIG || state64 == MNGSIG) {
yading@10:                 i++;
yading@10:                 ppc->pc.frame_start_found = 1;
yading@10:                 break;
yading@10:             }
yading@10:         }
yading@10:         ppc->pc.state64 = state64;
yading@10:     } else
yading@10:         if (ppc->remaining_size) {
yading@10:             i = FFMIN(ppc->remaining_size, buf_size);
yading@10:             ppc->remaining_size -= i;
yading@10:             if (ppc->remaining_size)
yading@10:                 goto flush;
yading@10:             if (ppc->index == -1) {
yading@10:                 next = i;
yading@10:                 goto flush;
yading@10:             }
yading@10:         }
yading@10: 
yading@10:     for (;ppc->pc.frame_start_found && i < buf_size; i++) {
yading@10:         ppc->pc.state = (ppc->pc.state<<8) | buf[i];
yading@10:         if (ppc->index == 3) {
yading@10:             ppc->chunk_length = ppc->pc.state;
yading@10:             if (ppc->chunk_length > 0x7fffffff) {
yading@10:                 ppc->index = ppc->pc.frame_start_found = 0;
yading@10:                 goto flush;
yading@10:             }
yading@10:             ppc->chunk_length += 4;
yading@10:         } else if (ppc->index == 7) {
yading@10:             if (ppc->chunk_length >= buf_size - i)
yading@10:                     ppc->remaining_size = ppc->chunk_length - buf_size + i + 1;
yading@10:             if (ppc->pc.state == MKBETAG('I', 'E', 'N', 'D')) {
yading@10:                 if (ppc->remaining_size)
yading@10:                     ppc->index = -1;
yading@10:                 else
yading@10:                     next = ppc->chunk_length + i + 1;
yading@10:                 break;
yading@10:             } else {
yading@10:                 ppc->index = 0;
yading@10:                 if (ppc->remaining_size)
yading@10:                     break;
yading@10:                 else
yading@10:                     i += ppc->chunk_length;
yading@10:                 continue;
yading@10:             }
yading@10:         }
yading@10:         ppc->index++;
yading@10:     }
yading@10: flush:
yading@10:     if (ff_combine_frame(&ppc->pc, next, &buf, &buf_size) < 0)
yading@10:         return buf_size;
yading@10: 
yading@10:     ppc->index = ppc->pc.frame_start_found = 0;
yading@10: 
yading@10:     *poutbuf      = buf;
yading@10:     *poutbuf_size = buf_size;
yading@10:     return next;
yading@10: }
yading@10: 
yading@10: AVCodecParser ff_png_parser = {
yading@10:     .codec_ids      = { AV_CODEC_ID_PNG },
yading@10:     .priv_data_size = sizeof(PNGParseContext),
yading@10:     .parser_parse   = png_parse,
yading@10:     .parser_close   = ff_parse_close,
yading@10: };