libavcodec/adx_parser.c

   1 /*
   2  * Copyright (c) 2011  Justin Ruggles
   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  * ADX audio parser
  24  *
  25  * Splits packets into individual blocks.
  26  */
  27
  28 #include "libavutil/intreadwrite.h"
  29 #include "parser.h"
  30 #include "adx.h"
  31
  32 typedef struct ADXParseContext {
  33     ParseContext pc;
  34     int header_size;
  35     int block_size;
  36     int remaining;
  37 } ADXParseContext;
  38
  39 static int adx_parse(AVCodecParserContext *s1,
  40                            AVCodecContext *avctx,
  41                            const uint8_t **poutbuf, int *poutbuf_size,
  42                            const uint8_t *buf, int buf_size)
  43 {
  44     ADXParseContext *s = s1->priv_data;
  45     ParseContext *pc = &s->pc;
  46     int next = END_NOT_FOUND;
  47     int i;
  48     uint64_t state = pc->state64;
  49
  50     if (!s->header_size) {
  51         for (i = 0; i < buf_size; i++) {
  52             state = (state << 8) | buf[i];
  53             /* check for fixed fields in ADX header for possible match */
  54             if ((state & 0xFFFF0000FFFFFF00) == 0x8000000003120400ULL) {
  55                 int channels    = state & 0xFF;
  56                 int header_size = ((state >> 32) & 0xFFFF) + 4;
  57                 if (channels > 0 && header_size >= 8) {
  58                     s->header_size = header_size;
  59                     s->block_size  = BLOCK_SIZE * channels;
  60                     s->remaining   = i - 7 + s->header_size + s->block_size;
  61                     break;
  62                 }
  63             }
  64         }
  65         pc->state64 = state;
  66     }
  67
  68     if (s->header_size) {
  69         if (!s->remaining)
  70             s->remaining = s->block_size;
  71         if (s->remaining <= buf_size) {
  72             next = s->remaining;
  73             s->remaining = 0;
  74         } else
  75             s->remaining -= buf_size;
  76     } else if (avctx->ch_layout.nb_channels > 0) {
  77         if (!s->block_size)
  78             s->block_size = avctx->ch_layout.nb_channels * BLOCK_SIZE;
  79         if (!s->remaining)
  80             s->remaining = s->block_size;
  81         if (s->remaining <= buf_size) {
  82             next = s->remaining;
  83             s->remaining = 0;
  84         } else
  85             s->remaining -= buf_size;
  86     }
  87
  88     if (ff_combine_frame(pc, next, &buf, &buf_size) < 0 || !buf_size) {
  89         *poutbuf      = NULL;
  90         *poutbuf_size = 0;
  91         return buf_size;
  92     }
  93
  94     s1->duration = BLOCK_SAMPLES;
  95
  96     *poutbuf = buf;
  97     *poutbuf_size = buf_size;
  98     return next;
  99 }
 100
 101 const AVCodecParser ff_adx_parser = {
 102     .codec_ids      = { AV_CODEC_ID_ADPCM_ADX },
 103     .priv_data_size = sizeof(ADXParseContext),
 104     .parser_parse   = adx_parse,
 105     .parser_close   = ff_parse_close,
 106 };