repositories / deb_ffmpeg.git / blame
| Commit | Line | Data |
|---|---|---|
| 2ba45a60 DM |
1 | /* |
| 2 | * copyright (c) 2008 Paul Kendall <paul@kcbbs.gen.nz> | |
| 3 | * | |
| 4 | * This file is part of FFmpeg. | |
| 5 | * | |
| 6 | * FFmpeg is free software; you can redistribute it and/or | |
| 7 | * modify it under the terms of the GNU Lesser General Public | |
| 8 | * License as published by the Free Software Foundation; either | |
| 9 | * version 2.1 of the License, or (at your option) any later version. | |
| 10 | * | |
| 11 | * FFmpeg is distributed in the hope that it will be useful, | |
| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 14 | * Lesser General Public License for more details. | |
| 15 | * | |
| 16 | * You should have received a copy of the GNU Lesser General Public | |
| 17 | * License along with FFmpeg; if not, write to the Free Software | |
| 18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
| 19 | */ | |
| 20 | ||
| 21 | /** | |
| 22 | * @file | |
| 23 | * AAC LATM parser | |
| 24 | */ | |
| 25 | ||
| 26 | #include <stdint.h> | |
| 27 | #include "parser.h" | |
| 28 | ||
| 29 | #define LATM_HEADER 0x56e000 // 0x2b7 (11 bits) | |
| 30 | #define LATM_MASK 0xFFE000 // top 11 bits | |
| 31 | #define LATM_SIZE_MASK 0x001FFF // bottom 13 bits | |
| 32 | ||
| 33 | typedef struct LATMParseContext{ | |
| 34 | ParseContext pc; | |
| 35 | int count; | |
| 36 | } LATMParseContext; | |
| 37 | ||
| 38 | /** | |
| 39 | * Find the end of the current frame in the bitstream. | |
| 40 | * @return the position of the first byte of the next frame, or -1 | |
| 41 | */ | |
| 42 | static int latm_find_frame_end(AVCodecParserContext *s1, const uint8_t *buf, | |
| 43 | int buf_size) | |
| 44 | { | |
| 45 | LATMParseContext *s = s1->priv_data; | |
| 46 | ParseContext *pc = &s->pc; | |
| 47 | int pic_found, i; | |
| 48 | uint32_t state; | |
| 49 | ||
| 50 | pic_found = pc->frame_start_found; | |
| 51 | state = pc->state; | |
| 52 | ||
| 53 | if (!pic_found) { | |
| 54 | for (i = 0; i < buf_size; i++) { | |
| 55 | state = (state<<8) | buf[i]; | |
| 56 | if ((state & LATM_MASK) == LATM_HEADER) { | |
| 57 | i++; | |
| 58 | s->count = -i; | |
| 59 | pic_found = 1; | |
| 60 | break; | |
| 61 | } | |
| 62 | } | |
| 63 | } | |
| 64 | ||
| 65 | if (pic_found) { | |
| 66 | /* EOF considered as end of frame */ | |
| 67 | if (buf_size == 0) | |
| 68 | return 0; | |
| 69 | if ((state & LATM_SIZE_MASK) - s->count <= buf_size) { | |
| 70 | pc->frame_start_found = 0; | |
| 71 | pc->state = -1; | |
| 72 | return (state & LATM_SIZE_MASK) - s->count; | |
| 73 | } | |
| 74 | } | |
| 75 | ||
| 76 | s->count += buf_size; | |
| 77 | pc->frame_start_found = pic_found; | |
| 78 | pc->state = state; | |
| 79 | ||
| 80 | return END_NOT_FOUND; | |
| 81 | } | |
| 82 | ||
| 83 | static int latm_parse(AVCodecParserContext *s1, AVCodecContext *avctx, | |
| 84 | const uint8_t **poutbuf, int *poutbuf_size, | |
| 85 | const uint8_t *buf, int buf_size) | |
| 86 | { | |
| 87 | LATMParseContext *s = s1->priv_data; | |
| 88 | ParseContext *pc = &s->pc; | |
| 89 | int next; | |
| 90 | ||
| 91 | if (s1->flags & PARSER_FLAG_COMPLETE_FRAMES) { | |
| 92 | next = buf_size; | |
| 93 | } else { | |
| 94 | next = latm_find_frame_end(s1, buf, buf_size); | |
| 95 | ||
| 96 | if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { | |
| 97 | *poutbuf = NULL; | |
| 98 | *poutbuf_size = 0; | |
| 99 | return buf_size; | |
| 100 | } | |
| 101 | } | |
| 102 | *poutbuf = buf; | |
| 103 | *poutbuf_size = buf_size; | |
| 104 | return next; | |
| 105 | } | |
| 106 | ||
| 107 | AVCodecParser ff_aac_latm_parser = { | |
| 108 | .codec_ids = { AV_CODEC_ID_AAC_LATM }, | |
| 109 | .priv_data_size = sizeof(LATMParseContext), | |
| 110 | .parser_parse = latm_parse, | |
| 111 | .parser_close = ff_parse_close | |
| 112 | }; |