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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 4349 | Serge | 1 | /* |
| 2 | * Dirac parser |
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| 3 | * |
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| 4 | * Copyright (c) 2007-2008 Marco Gerards |
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| 5 | * Copyright (c) 2008 BBC, Anuradha Suraparaju |
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| 6 | * |
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| 7 | * This file is part of FFmpeg. |
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| 8 | * |
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| 9 | * FFmpeg is free software; you can redistribute it and/or |
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| 10 | * modify it under the terms of the GNU Lesser General Public |
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| 11 | * License as published by the Free Software Foundation; either |
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| 12 | * version 2.1 of the License, or (at your option) any later version. |
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| 13 | * |
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| 14 | * FFmpeg is distributed in the hope that it will be useful, |
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| 15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 17 | * Lesser General Public License for more details. |
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| 18 | * |
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| 19 | * You should have received a copy of the GNU Lesser General Public |
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| 20 | * License along with FFmpeg; if not, write to the Free Software |
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| 21 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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| 22 | */ |
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| 23 | |||
| 24 | /** |
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| 25 | * @file |
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| 26 | * Dirac Parser |
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| 27 | * @author Marco Gerards |
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| 28 | */ |
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| 29 | |||
| 30 | #include |
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| 31 | |||
| 32 | #include "libavutil/intreadwrite.h" |
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| 33 | #include "libavutil/mem.h" |
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| 34 | #include "parser.h" |
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| 35 | |||
| 36 | #define DIRAC_PARSE_INFO_PREFIX 0x42424344 |
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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 | typedef struct DiracParseContext { |
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| 43 | int state; |
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| 44 | int is_synced; |
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| 45 | int sync_offset; |
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| 46 | int header_bytes_needed; |
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| 47 | int overread_index; |
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| 48 | int buffer_size; |
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| 49 | int index; |
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| 50 | uint8_t *buffer; |
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| 51 | int dirac_unit_size; |
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| 52 | uint8_t *dirac_unit; |
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| 53 | } DiracParseContext; |
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| 54 | |||
| 55 | static int find_frame_end(DiracParseContext *pc, |
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| 56 | const uint8_t *buf, int buf_size) |
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| 57 | { |
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| 58 | uint32_t state = pc->state; |
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| 59 | int i = 0; |
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| 60 | |||
| 61 | if (!pc->is_synced) { |
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| 62 | for (i = 0; i < buf_size; i++) { |
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| 63 | state = (state << 8) | buf[i]; |
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| 64 | if (state == DIRAC_PARSE_INFO_PREFIX) { |
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| 65 | state = -1; |
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| 66 | pc->is_synced = 1; |
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| 67 | pc->header_bytes_needed = 9; |
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| 68 | pc->sync_offset = i; |
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| 69 | break; |
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| 70 | } |
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| 71 | } |
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| 72 | } |
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| 73 | |||
| 74 | if (pc->is_synced) { |
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| 75 | pc->sync_offset = 0; |
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| 76 | for (; i < buf_size; i++) { |
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| 77 | if (state == DIRAC_PARSE_INFO_PREFIX) { |
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| 78 | if ((buf_size-i) >= pc->header_bytes_needed) { |
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| 79 | pc->state = -1; |
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| 80 | return i + pc->header_bytes_needed; |
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| 81 | } else { |
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| 82 | pc->header_bytes_needed = 9-(buf_size-i); |
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| 83 | break; |
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| 84 | } |
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| 85 | } else |
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| 86 | state = (state << 8) | buf[i]; |
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| 87 | } |
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| 88 | } |
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| 89 | pc->state = state; |
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| 90 | return -1; |
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| 91 | } |
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| 92 | |||
| 93 | typedef struct DiracParseUnit |
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| 94 | { |
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| 95 | int next_pu_offset; |
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| 96 | int prev_pu_offset; |
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| 97 | uint8_t pu_type; |
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| 98 | } DiracParseUnit; |
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| 99 | |||
| 100 | static int unpack_parse_unit(DiracParseUnit *pu, DiracParseContext *pc, |
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| 101 | int offset) |
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| 102 | { |
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| 103 | uint8_t *start = pc->buffer + offset; |
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| 104 | uint8_t *end = pc->buffer + pc->index; |
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| 105 | if (start < pc->buffer || (start+13 > end)) |
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| 106 | return 0; |
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| 107 | pu->pu_type = start[4]; |
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| 108 | |||
| 109 | pu->next_pu_offset = AV_RB32(start+5); |
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| 110 | pu->prev_pu_offset = AV_RB32(start+9); |
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| 111 | |||
| 112 | if (pu->pu_type == 0x10 && pu->next_pu_offset == 0) |
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| 113 | pu->next_pu_offset = 13; |
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| 114 | |||
| 115 | return 1; |
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| 116 | } |
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| 117 | |||
| 118 | static int dirac_combine_frame(AVCodecParserContext *s, AVCodecContext *avctx, |
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| 119 | int next, const uint8_t **buf, int *buf_size) |
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| 120 | { |
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| 121 | int parse_timing_info = (s->pts == AV_NOPTS_VALUE && |
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| 122 | s->dts == AV_NOPTS_VALUE); |
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| 123 | DiracParseContext *pc = s->priv_data; |
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| 124 | |||
| 125 | if (pc->overread_index) { |
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| 126 | memcpy(pc->buffer, pc->buffer + pc->overread_index, |
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| 127 | pc->index - pc->overread_index); |
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| 128 | pc->index -= pc->overread_index; |
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| 129 | pc->overread_index = 0; |
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| 130 | if (*buf_size == 0 && pc->buffer[4] == 0x10) { |
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| 131 | *buf = pc->buffer; |
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| 132 | *buf_size = pc->index; |
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| 133 | return 0; |
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| 134 | } |
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| 135 | } |
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| 136 | |||
| 137 | if ( next == -1) { |
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| 138 | /* Found a possible frame start but not a frame end */ |
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| 139 | void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size, |
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| 140 | pc->index + (*buf_size - |
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| 141 | pc->sync_offset)); |
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| 142 | pc->buffer = new_buffer; |
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| 143 | memcpy(pc->buffer+pc->index, (*buf + pc->sync_offset), |
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| 144 | *buf_size - pc->sync_offset); |
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| 145 | pc->index += *buf_size - pc->sync_offset; |
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| 146 | return -1; |
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| 147 | } else { |
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| 148 | /* Found a possible frame start and a possible frame end */ |
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| 149 | DiracParseUnit pu1, pu; |
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| 150 | void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size, |
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| 151 | pc->index + next); |
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| 152 | pc->buffer = new_buffer; |
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| 153 | memcpy(pc->buffer + pc->index, *buf, next); |
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| 154 | pc->index += next; |
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| 155 | |||
| 156 | /* Need to check if we have a valid Parse Unit. We can't go by the |
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| 157 | * sync pattern 'BBCD' alone because arithmetic coding of the residual |
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| 158 | * and motion data can cause the pattern triggering a false start of |
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| 159 | * frame. So check if the previous parse offset of the next parse unit |
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| 160 | * is equal to the next parse offset of the current parse unit then |
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| 161 | * we can be pretty sure that we have a valid parse unit */ |
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| 162 | if (!unpack_parse_unit(&pu1, pc, pc->index - 13) || |
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| 163 | !unpack_parse_unit(&pu, pc, pc->index - 13 - pu1.prev_pu_offset) || |
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| 164 | pu.next_pu_offset != pu1.prev_pu_offset || |
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| 165 | pc->index < pc->dirac_unit_size + 13LL + pu1.prev_pu_offset |
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| 166 | ) { |
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| 167 | pc->index -= 9; |
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| 168 | *buf_size = next-9; |
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| 169 | pc->header_bytes_needed = 9; |
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| 170 | return -1; |
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| 171 | } |
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| 172 | |||
| 173 | /* All non-frame data must be accompanied by frame data. This is to |
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| 174 | * ensure that pts is set correctly. So if the current parse unit is |
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| 175 | * not frame data, wait for frame data to come along */ |
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| 176 | |||
| 177 | pc->dirac_unit = pc->buffer + pc->index - 13 - |
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| 178 | pu1.prev_pu_offset - pc->dirac_unit_size; |
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| 179 | |||
| 180 | pc->dirac_unit_size += pu.next_pu_offset; |
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| 181 | |||
| 182 | if ((pu.pu_type&0x08) != 0x08) { |
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| 183 | pc->header_bytes_needed = 9; |
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| 184 | *buf_size = next; |
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| 185 | return -1; |
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| 186 | } |
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| 187 | |||
| 188 | /* Get the picture number to set the pts and dts*/ |
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| 189 | if (parse_timing_info) { |
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| 190 | uint8_t *cur_pu = pc->buffer + |
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| 191 | pc->index - 13 - pu1.prev_pu_offset; |
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| 192 | int pts = AV_RB32(cur_pu + 13); |
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| 193 | if (s->last_pts == 0 && s->last_dts == 0) |
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| 194 | s->dts = pts - 1; |
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| 195 | else |
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| 196 | s->dts = s->last_dts+1; |
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| 197 | s->pts = pts; |
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| 198 | if (!avctx->has_b_frames && (cur_pu[4] & 0x03)) |
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| 199 | avctx->has_b_frames = 1; |
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| 200 | } |
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| 201 | if (avctx->has_b_frames && s->pts == s->dts) |
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| 202 | s->pict_type = AV_PICTURE_TYPE_B; |
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| 203 | |||
| 204 | /* Finally have a complete Dirac data unit */ |
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| 205 | *buf = pc->dirac_unit; |
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| 206 | *buf_size = pc->dirac_unit_size; |
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| 207 | |||
| 208 | pc->dirac_unit_size = 0; |
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| 209 | pc->overread_index = pc->index-13; |
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| 210 | pc->header_bytes_needed = 9; |
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| 211 | } |
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| 212 | return next; |
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| 213 | } |
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| 214 | |||
| 215 | static int dirac_parse(AVCodecParserContext *s, AVCodecContext *avctx, |
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| 216 | const uint8_t **poutbuf, int *poutbuf_size, |
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| 217 | const uint8_t *buf, int buf_size) |
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| 218 | { |
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| 219 | DiracParseContext *pc = s->priv_data; |
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| 220 | int next; |
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| 221 | |||
| 222 | *poutbuf = NULL; |
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| 223 | *poutbuf_size = 0; |
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| 224 | |||
| 225 | if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) { |
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| 226 | next = buf_size; |
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| 227 | *poutbuf = buf; |
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| 228 | *poutbuf_size = buf_size; |
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| 229 | /* Assume that data has been packetized into an encapsulation unit. */ |
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| 230 | } else { |
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| 231 | next = find_frame_end(pc, buf, buf_size); |
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| 232 | if (!pc->is_synced && next == -1) { |
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| 233 | /* No frame start found yet. So throw away the entire buffer. */ |
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| 234 | return buf_size; |
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| 235 | } |
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| 236 | |||
| 237 | if (dirac_combine_frame(s, avctx, next, &buf, &buf_size) < 0) { |
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| 238 | return buf_size; |
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| 239 | } |
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| 240 | } |
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| 241 | |||
| 242 | *poutbuf = buf; |
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| 243 | *poutbuf_size = buf_size; |
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| 244 | return next; |
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| 245 | } |
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| 246 | |||
| 247 | static void dirac_parse_close(AVCodecParserContext *s) |
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| 248 | { |
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| 249 | DiracParseContext *pc = s->priv_data; |
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| 250 | |||
| 251 | if (pc->buffer_size > 0) |
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| 252 | av_free(pc->buffer); |
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| 253 | } |
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| 254 | |||
| 255 | AVCodecParser ff_dirac_parser = { |
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| 256 | .codec_ids = { AV_CODEC_ID_DIRAC }, |
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| 257 | .priv_data_size = sizeof(DiracParseContext), |
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| 258 | .parser_parse = dirac_parse, |
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| 259 | .parser_close = dirac_parse_close, |
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| 260 | }; |