| /* |
| * LATM parser |
| * Copyright (c) 2008 Paul Kendall <paul@kcbbs.gen.nz> |
| * |
| * 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 |
| */ |
| |
| /** |
| * @file latm_parser.c |
| * LATM parser |
| */ |
| |
| #include "parser.h" |
| |
| #define LATM_HEADER 0x56e000 // 0x2b7 (11 bits) |
| #define LATM_MASK 0xFFE000 // top 11 bits |
| #define LATM_SIZE_MASK 0x001FFF // bottom 13 bits |
| |
| typedef struct LATMParseContext{ |
| ParseContext pc; |
| int count; |
| } LATMParseContext; |
| |
| /** |
| * finds the end of the current frame in the bitstream. |
| * @return the position of the first byte of the next frame, or -1 |
| */ |
| static int latm_find_frame_end(AVCodecParserContext *s1, const uint8_t *buf, |
| int buf_size) { |
| LATMParseContext *s = s1->priv_data; |
| ParseContext *pc = &s->pc; |
| int pic_found, i; |
| uint32_t state; |
| |
| pic_found = pc->frame_start_found; |
| state = pc->state; |
| |
| i = 0; |
| if(!pic_found){ |
| for(i=0; i<buf_size; i++){ |
| state = (state<<8) | buf[i]; |
| if((state & LATM_MASK) == LATM_HEADER){ |
| i++; |
| s->count = - i; |
| pic_found=1; |
| break; |
| } |
| } |
| } |
| |
| if(pic_found){ |
| /* EOF considered as end of frame */ |
| if (buf_size == 0) |
| return 0; |
| if((state & LATM_SIZE_MASK) - s->count <= buf_size) { |
| pc->frame_start_found = 0; |
| pc->state = -1; |
| return (state & LATM_SIZE_MASK) - s->count; |
| } |
| } |
| |
| s->count += buf_size; |
| pc->frame_start_found = pic_found; |
| pc->state = state; |
| return END_NOT_FOUND; |
| } |
| |
| static int latm_parse(AVCodecParserContext *s1, |
| AVCodecContext *avctx, |
| const uint8_t **poutbuf, int *poutbuf_size, |
| const uint8_t *buf, int buf_size) |
| { |
| LATMParseContext *s = s1->priv_data; |
| ParseContext *pc = &s->pc; |
| int next; |
| |
| if(s1->flags & PARSER_FLAG_COMPLETE_FRAMES){ |
| next = buf_size; |
| }else{ |
| next = latm_find_frame_end(s1, buf, buf_size); |
| |
| if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { |
| *poutbuf = NULL; |
| *poutbuf_size = 0; |
| return buf_size; |
| } |
| } |
| *poutbuf = buf; |
| *poutbuf_size = buf_size; |
| return next; |
| } |
| |
| static int latm_split(AVCodecContext *avctx, |
| const uint8_t *buf, int buf_size) |
| { |
| int i; |
| uint32_t state= -1; |
| |
| for(i=0; i<buf_size; i++){ |
| state= (state<<8) | buf[i]; |
| if((state & LATM_MASK) == LATM_HEADER) |
| return i-2; |
| } |
| return 0; |
| } |
| |
| AVCodecParser aac_latm_parser = { |
| { CODEC_ID_AAC_LATM }, |
| sizeof(LATMParseContext), |
| NULL, |
| latm_parse, |
| ff_parse_close, |
| latm_split, |
| }; |