dca_parser.c 5.13 KB
Newer Older
1 2 3 4 5 6 7
/*
 * DCA parser
 * Copyright (C) 2004 Gildas Bazin
 * Copyright (C) 2004 Benjamin Zores
 * Copyright (C) 2006 Benjamin Larsson
 * Copyright (C) 2007 Konstantin Shishkov
 *
8
 * This file is part of Libav.
9
 *
10
 * Libav is free software; you can redistribute it and/or
11 12 13 14
 * 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.
 *
15
 * Libav is distributed in the hope that it will be useful,
16 17 18 19 20
 * 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
21
 * License along with Libav; if not, write to the Free Software
22 23 24 25 26
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "parser.h"
#include "dca.h"
27
#include "get_bits.h"
28 29 30 31

typedef struct DCAParseContext {
    ParseContext pc;
    uint32_t lastmarker;
32 33
    int size;
    int framesize;
34
    int hd_pos;
35 36 37 38 39 40 41 42
} DCAParseContext;

#define IS_MARKER(state, i, buf, buf_size) \
 ((state == DCA_MARKER_14B_LE && (i < buf_size-2) && (buf[i+1] & 0xF0) == 0xF0 && buf[i+2] == 0x07) \
 || (state == DCA_MARKER_14B_BE && (i < buf_size-2) && buf[i+1] == 0x07 && (buf[i+2] & 0xF0) == 0xF0) \
 || state == DCA_MARKER_RAW_LE || state == DCA_MARKER_RAW_BE)

/**
43
 * Find the end of the current frame in the bitstream.
44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73
 * @return the position of the first byte of the next frame, or -1
 */
static int dca_find_frame_end(DCAParseContext * pc1, const uint8_t * buf,
                              int buf_size)
{
    int start_found, i;
    uint32_t state;
    ParseContext *pc = &pc1->pc;

    start_found = pc->frame_start_found;
    state = pc->state;

    i = 0;
    if (!start_found) {
        for (i = 0; i < buf_size; i++) {
            state = (state << 8) | buf[i];
            if (IS_MARKER(state, i, buf, buf_size)) {
                if (pc1->lastmarker && state == pc1->lastmarker) {
                    start_found = 1;
                    break;
                } else if (!pc1->lastmarker) {
                    start_found = 1;
                    pc1->lastmarker = state;
                    break;
                }
            }
        }
    }
    if (start_found) {
        for (; i < buf_size; i++) {
74
            pc1->size++;
75
            state = (state << 8) | buf[i];
76 77 78 79 80 81 82 83
            if (state == DCA_HD_MARKER && !pc1->hd_pos)
                pc1->hd_pos = pc1->size;
            if (state == pc1->lastmarker && IS_MARKER(state, i, buf, buf_size)) {
                if(pc1->framesize > pc1->size)
                    continue;
                if(!pc1->framesize){
                    pc1->framesize = pc1->hd_pos ? pc1->hd_pos : pc1->size;
                }
84 85
                pc->frame_start_found = 0;
                pc->state = -1;
86
                pc1->size = 0;
87 88 89 90 91 92 93 94 95
                return i - 3;
            }
        }
    }
    pc->frame_start_found = start_found;
    pc->state = state;
    return END_NOT_FOUND;
}

96
static av_cold int dca_parse_init(AVCodecParserContext * s)
97 98 99 100 101 102 103
{
    DCAParseContext *pc1 = s->priv_data;

    pc1->lastmarker = 0;
    return 0;
}

104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126
static int dca_parse_params(const uint8_t *buf, int buf_size, int *duration,
                            int *sample_rate)
{
    GetBitContext gb;
    uint8_t hdr[12 + FF_INPUT_BUFFER_PADDING_SIZE] = { 0 };
    int ret, sample_blocks, sr_code;

    if (buf_size < 12)
        return AVERROR_INVALIDDATA;

    if ((ret = ff_dca_convert_bitstream(buf, 12, hdr, 12)) < 0)
        return ret;

    init_get_bits(&gb, hdr, 96);

    skip_bits_long(&gb, 39);
    sample_blocks = get_bits(&gb, 7) + 1;
    if (sample_blocks < 8)
        return AVERROR_INVALIDDATA;
    *duration = 256 * (sample_blocks / 8);

    skip_bits(&gb, 20);
    sr_code = get_bits(&gb, 4);
127
    *sample_rate = avpriv_dca_sample_rates[sr_code];
128 129 130 131 132 133
    if (*sample_rate == 0)
        return AVERROR_INVALIDDATA;

    return 0;
}

134 135
static int dca_parse(AVCodecParserContext * s,
                     AVCodecContext * avctx,
136
                     const uint8_t ** poutbuf, int *poutbuf_size,
137 138 139 140
                     const uint8_t * buf, int buf_size)
{
    DCAParseContext *pc1 = s->priv_data;
    ParseContext *pc = &pc1->pc;
141
    int next, duration, sample_rate;
142 143 144 145 146 147

    if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
        next = buf_size;
    } else {
        next = dca_find_frame_end(pc1, buf, buf_size);

148
        if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
149 150 151 152 153
            *poutbuf = NULL;
            *poutbuf_size = 0;
            return buf_size;
        }
    }
154 155 156 157

    /* read the duration and sample rate from the frame header */
    if (!dca_parse_params(buf, buf_size, &duration, &sample_rate)) {
        s->duration = duration;
158
        avctx->sample_rate = sample_rate;
159 160 161
    } else
        s->duration = 0;

162
    *poutbuf = buf;
163 164 165 166
    *poutbuf_size = buf_size;
    return next;
}

167
AVCodecParser ff_dca_parser = {
168
    .codec_ids      = { AV_CODEC_ID_DTS },
169 170 171 172
    .priv_data_size = sizeof(DCAParseContext),
    .parser_init    = dca_parse_init,
    .parser_parse   = dca_parse,
    .parser_close   = ff_parse_close,
173
};