ffmpeg/libavcodec/dca_parser.c

   1 /*
   2  * DCA parser
   3  * Copyright (C) 2004 Gildas Bazin
   4  * Copyright (C) 2004 Benjamin Zores
   5  * Copyright (C) 2006 Benjamin Larsson
   6  * Copyright (C) 2007 Konstantin Shishkov
   7  *
   8  * This file is part of FFmpeg.
   9  *
  10  * FFmpeg is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU Lesser General Public
  12  * License as published by the Free Software Foundation; either
  13  * version 2.1 of the License, or (at your option) any later version.
  14  *
  15  * FFmpeg is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * Lesser General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public
  21  * License along with FFmpeg; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  23  */
  24
  25 #include "dca.h"
  26 #include "get_bits.h"
  27 #include "parser.h"
  28
  29 typedef struct DCAParseContext {
  30     ParseContext pc;
  31     uint32_t lastmarker;
  32     int size;
  33     int framesize;
  34     int hd_pos;
  35 } DCAParseContext;
  36
  37 #define IS_MARKER(state, i, buf, buf_size) \
  38     ((state == DCA_MARKER_14B_LE && (i < buf_size - 2) && (buf[i + 1] & 0xF0) == 0xF0 &&  buf[i + 2]         == 0x07) || \
  39      (state == DCA_MARKER_14B_BE && (i < buf_size - 2) &&  buf[i + 1]         == 0x07 && (buf[i + 2] & 0xF0) == 0xF0) || \
  40       state == DCA_MARKER_RAW_LE || state == DCA_MARKER_RAW_BE || state == DCA_HD_MARKER)
  41
  42 /**
  43  * Find the end of the current frame in the bitstream.
  44  * @return the position of the first byte of the next frame, or -1
  45  */
  46 static int dca_find_frame_end(DCAParseContext *pc1, const uint8_t *buf,
  47                               int buf_size)
  48 {
  49     int start_found, i;
  50     uint32_t state;
  51     ParseContext *pc = &pc1->pc;
  52
  53     start_found = pc->frame_start_found;
  54     state       = pc->state;
  55
  56     i = 0;
  57     if (!start_found) {
  58         for (i = 0; i < buf_size; i++) {
  59             state = (state << 8) | buf[i];
  60             if (IS_MARKER(state, i, buf, buf_size)) {
  61                 if (!pc1->lastmarker || state == pc1->lastmarker || pc1->lastmarker == DCA_HD_MARKER) {
  62                     start_found     = 1;
  63                     pc1->lastmarker = state;
  64                     i++;
  65                     break;
  66                 }
  67             }
  68         }
  69     }
  70     if (start_found) {
  71         for (; i < buf_size; i++) {
  72             pc1->size++;
  73             state = (state << 8) | buf[i];
  74             if (state == DCA_HD_MARKER && !pc1->hd_pos)
  75                 pc1->hd_pos = pc1->size;
  76             if (IS_MARKER(state, i, buf, buf_size) && (state == pc1->lastmarker || pc1->lastmarker == DCA_HD_MARKER)) {
  77                 if (pc1->framesize > pc1->size)
  78                     continue;
  79                 pc->frame_start_found = 0;
  80                 pc->state             = -1;
  81                 pc1->size             = 0;
  82                 return i - 3;
  83             }
  84         }
  85     }
  86     pc->frame_start_found = start_found;
  87     pc->state             = state;
  88     return END_NOT_FOUND;
  89 }
  90
  91 static av_cold int dca_parse_init(AVCodecParserContext *s)
  92 {
  93     DCAParseContext *pc1 = s->priv_data;
  94
  95     pc1->lastmarker = 0;
  96     return 0;
  97 }
  98
  99 static int dca_parse_params(const uint8_t *buf, int buf_size, int *duration,
 100                             int *sample_rate, int *framesize)
 101 {
 102     GetBitContext gb;
 103     uint8_t hdr[12 + FF_INPUT_BUFFER_PADDING_SIZE] = { 0 };
 104     int ret, sample_blocks, sr_code;
 105
 106     if (buf_size < 12)
 107         return AVERROR_INVALIDDATA;
 108
 109     if ((ret = avpriv_dca_convert_bitstream(buf, 12, hdr, 12)) < 0)
 110         return ret;
 111
 112     init_get_bits(&gb, hdr, 96);
 113
 114     skip_bits_long(&gb, 39);
 115     sample_blocks = get_bits(&gb, 7) + 1;
 116     if (sample_blocks < 8)
 117         return AVERROR_INVALIDDATA;
 118     *duration = 256 * (sample_blocks / 8);
 119
 120     *framesize = get_bits(&gb, 14) + 1;
 121     if (*framesize < 95)
 122         return AVERROR_INVALIDDATA;
 123
 124     skip_bits(&gb, 6);
 125     sr_code      = get_bits(&gb, 4);
 126     *sample_rate = avpriv_dca_sample_rates[sr_code];
 127     if (*sample_rate == 0)
 128         return AVERROR_INVALIDDATA;
 129
 130     return 0;
 131 }
 132
 133 static int dca_parse(AVCodecParserContext *s, AVCodecContext *avctx,
 134                      const uint8_t **poutbuf, int *poutbuf_size,
 135                      const uint8_t *buf, int buf_size)
 136 {
 137     DCAParseContext *pc1 = s->priv_data;
 138     ParseContext *pc = &pc1->pc;
 139     int next, duration, sample_rate;
 140
 141     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
 142         next = buf_size;
 143     } else {
 144         next = dca_find_frame_end(pc1, buf, buf_size);
 145
 146         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 147             *poutbuf      = NULL;
 148             *poutbuf_size = 0;
 149             return buf_size;
 150         }
 151     }
 152
 153     /* read the duration and sample rate from the frame header */
 154     if (!dca_parse_params(buf, buf_size, &duration, &sample_rate, &pc1->framesize)) {
 155         s->duration        = duration;
 156         avctx->sample_rate = sample_rate;
 157     } else
 158         s->duration = 0;
 159
 160     *poutbuf      = buf;
 161     *poutbuf_size = buf_size;
 162     return next;
 163 }
 164
 165 AVCodecParser ff_dca_parser = {
 166     .codec_ids      = { AV_CODEC_ID_DTS },
 167     .priv_data_size = sizeof(DCAParseContext),
 168     .parser_init    = dca_parse_init,
 169     .parser_parse   = dca_parse,
 170     .parser_close   = ff_parse_close,
 171 };