libavcodec/sbc_parser.c

   1 /*
   2  * SBC parser
   3  *
   4  * Copyright (C) 2017  Aurelien Jacobs <aurel@gnuage.org>
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include "sbc.h"
  24 #include "parser.h"
  25
  26 typedef struct SBCParseContext {
  27     ParseContext pc;
  28     uint8_t header[3];
  29     int header_size;
  30     int buffered_size;
  31 } SBCParseContext;
  32
  33 static int sbc_parse_header(AVCodecParserContext *s, AVCodecContext *avctx,
  34                             const uint8_t *data, size_t len)
  35 {
  36     static const int sample_rates[4] = { 16000, 32000, 44100, 48000 };
  37     int sr, blocks, mode, subbands, bitpool, channels, joint;
  38     int length;
  39
  40     if (len < 3)
  41         return -1;
  42
  43     if (data[0] == MSBC_SYNCWORD && data[1] == 0 && data[2] == 0) {
  44         av_channel_layout_uninit(&avctx->ch_layout);
  45         avctx->ch_layout.order       = AV_CHANNEL_ORDER_UNSPEC;
  46         avctx->ch_layout.nb_channels = 1;
  47         avctx->sample_rate = 16000;
  48         avctx->frame_size = 120;
  49         s->duration = avctx->frame_size;
  50         return 57;
  51     }
  52
  53     if (data[0] != SBC_SYNCWORD)
  54         return -2;
  55
  56     sr       =   (data[1] >> 6) & 0x03;
  57     blocks   = (((data[1] >> 4) & 0x03) + 1) << 2;
  58     mode     =   (data[1] >> 2) & 0x03;
  59     subbands = (((data[1] >> 0) & 0x01) + 1) << 2;
  60     bitpool  = data[2];
  61
  62     channels = mode == SBC_MODE_MONO ? 1 : 2;
  63     joint    = mode == SBC_MODE_JOINT_STEREO;
  64
  65     length = 4 + (subbands * channels) / 2
  66              + ((((mode == SBC_MODE_DUAL_CHANNEL) + 1) * blocks * bitpool
  67                  + (joint * subbands)) + 7) / 8;
  68
  69     av_channel_layout_uninit(&avctx->ch_layout);
  70     avctx->ch_layout.order       = AV_CHANNEL_ORDER_UNSPEC;
  71     avctx->ch_layout.nb_channels = channels;
  72     avctx->sample_rate = sample_rates[sr];
  73     avctx->frame_size = subbands * blocks;
  74     s->duration = avctx->frame_size;
  75     return length;
  76 }
  77
  78 static int sbc_parse(AVCodecParserContext *s, AVCodecContext *avctx,
  79                      const uint8_t **poutbuf, int *poutbuf_size,
  80                      const uint8_t *buf, int buf_size)
  81 {
  82     SBCParseContext *pc = s->priv_data;
  83     int next;
  84
  85     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
  86         next = buf_size;
  87     } else {
  88         if (pc->header_size) {
  89             memcpy(pc->header + pc->header_size, buf,
  90                    sizeof(pc->header) - pc->header_size);
  91             next = sbc_parse_header(s, avctx, pc->header, sizeof(pc->header))
  92                  - pc->buffered_size;
  93             pc->header_size = 0;
  94         } else {
  95             next = sbc_parse_header(s, avctx, buf, buf_size);
  96             if (next >= buf_size)
  97                 next = -1;
  98         }
  99
 100         if (next < 0) {
 101             pc->header_size = FFMIN(sizeof(pc->header), buf_size);
 102             memcpy(pc->header, buf, pc->header_size);
 103             pc->buffered_size = buf_size;
 104             next = END_NOT_FOUND;
 105         }
 106
 107         if (ff_combine_frame(&pc->pc, next, &buf, &buf_size) < 0) {
 108             *poutbuf      = NULL;
 109             *poutbuf_size = 0;
 110             return buf_size;
 111         }
 112     }
 113
 114     *poutbuf      = buf;
 115     *poutbuf_size = buf_size;
 116     return next;
 117 }
 118
 119 const AVCodecParser ff_sbc_parser = {
 120     .codec_ids      = { AV_CODEC_ID_SBC },
 121     .priv_data_size = sizeof(SBCParseContext),
 122     .parser_parse   = sbc_parse,
 123     .parser_close   = ff_parse_close,
 124 };