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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 4349 | Serge | 1 | /* |
| 2 | * copyright (c) 2008 Paul Kendall |
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| 3 | * |
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| 4 | * This file is part of FFmpeg. |
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| 5 | * |
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| 6 | * FFmpeg is free software; you can redistribute it and/or |
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| 7 | * modify it under the terms of the GNU Lesser General Public |
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| 8 | * License as published by the Free Software Foundation; either |
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| 9 | * version 2.1 of the License, or (at your option) any later version. |
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| 10 | * |
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| 11 | * FFmpeg is distributed in the hope that it will be useful, |
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| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 14 | * Lesser General Public License for more details. |
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| 15 | * |
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| 16 | * You should have received a copy of the GNU Lesser General Public |
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| 17 | * License along with FFmpeg; if not, write to the Free Software |
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| 18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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| 19 | */ |
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| 20 | |||
| 21 | /** |
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| 22 | * @file |
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| 23 | * AAC LATM parser |
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| 24 | */ |
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| 25 | |||
| 26 | #include |
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| 27 | #include "parser.h" |
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| 28 | |||
| 29 | #define LATM_HEADER 0x56e000 // 0x2b7 (11 bits) |
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| 30 | #define LATM_MASK 0xFFE000 // top 11 bits |
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| 31 | #define LATM_SIZE_MASK 0x001FFF // bottom 13 bits |
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| 32 | |||
| 33 | typedef struct LATMParseContext{ |
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| 34 | ParseContext pc; |
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| 35 | int count; |
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| 36 | } LATMParseContext; |
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| 37 | |||
| 38 | /** |
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| 39 | * Find the end of the current frame in the bitstream. |
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| 40 | * @return the position of the first byte of the next frame, or -1 |
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| 41 | */ |
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| 42 | static int latm_find_frame_end(AVCodecParserContext *s1, const uint8_t *buf, |
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| 43 | int buf_size) |
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| 44 | { |
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| 45 | LATMParseContext *s = s1->priv_data; |
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| 46 | ParseContext *pc = &s->pc; |
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| 47 | int pic_found, i; |
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| 48 | uint32_t state; |
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| 49 | |||
| 50 | pic_found = pc->frame_start_found; |
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| 51 | state = pc->state; |
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| 52 | |||
| 53 | if (!pic_found) { |
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| 54 | for (i = 0; i < buf_size; i++) { |
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| 55 | state = (state<<8) | buf[i]; |
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| 56 | if ((state & LATM_MASK) == LATM_HEADER) { |
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| 57 | i++; |
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| 58 | s->count = -i; |
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| 59 | pic_found = 1; |
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| 60 | break; |
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| 61 | } |
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| 62 | } |
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| 63 | } |
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| 64 | |||
| 65 | if (pic_found) { |
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| 66 | /* EOF considered as end of frame */ |
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| 67 | if (buf_size == 0) |
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| 68 | return 0; |
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| 69 | if ((state & LATM_SIZE_MASK) - s->count <= buf_size) { |
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| 70 | pc->frame_start_found = 0; |
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| 71 | pc->state = -1; |
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| 72 | return (state & LATM_SIZE_MASK) - s->count; |
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| 73 | } |
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| 74 | } |
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| 75 | |||
| 76 | s->count += buf_size; |
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| 77 | pc->frame_start_found = pic_found; |
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| 78 | pc->state = state; |
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| 79 | |||
| 80 | return END_NOT_FOUND; |
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| 81 | } |
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| 82 | |||
| 83 | static int latm_parse(AVCodecParserContext *s1, AVCodecContext *avctx, |
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| 84 | const uint8_t **poutbuf, int *poutbuf_size, |
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| 85 | const uint8_t *buf, int buf_size) |
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| 86 | { |
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| 87 | LATMParseContext *s = s1->priv_data; |
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| 88 | ParseContext *pc = &s->pc; |
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| 89 | int next; |
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| 90 | |||
| 91 | if (s1->flags & PARSER_FLAG_COMPLETE_FRAMES) { |
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| 92 | next = buf_size; |
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| 93 | } else { |
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| 94 | next = latm_find_frame_end(s1, buf, buf_size); |
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| 95 | |||
| 96 | if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { |
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| 97 | *poutbuf = NULL; |
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| 98 | *poutbuf_size = 0; |
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| 99 | return buf_size; |
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| 100 | } |
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| 101 | } |
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| 102 | *poutbuf = buf; |
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| 103 | *poutbuf_size = buf_size; |
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| 104 | return next; |
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| 105 | } |
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| 106 | |||
| 107 | AVCodecParser ff_aac_latm_parser = { |
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| 108 | .codec_ids = { AV_CODEC_ID_AAC_LATM }, |
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| 109 | .priv_data_size = sizeof(LATMParseContext), |
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| 110 | .parser_parse = latm_parse, |
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| 111 | .parser_close = ff_parse_close |
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| 112 | }; |