mp3dec.c

   1 /*
   2  * Copyright (C) 2005-2006 Andre Noll <maan@systemlinux.org>
   3  *
   4  *     This program is free software; you can redistribute it and/or modify
   5  *     it under the terms of the GNU General Public License as published by
   6  *     the Free Software Foundation; either version 2 of the License, or
   7  *     (at your option) any later version.
   8  *
   9  *     This program is distributed in the hope that it will be useful,
  10  *     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *     GNU General Public License for more details.
  13  *
  14  *     You should have received a copy of the GNU General Public License
  15  *     along with this program; if not, write to the Free Software
  16  *     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  17  */
  18
  19 /** \file mp3dec.c paraslash's mp3 decoder */
  20
  21 #include "gcc-compat.h"
  22 #include "para.h"
  23
  24 #include "list.h"
  25 #include "filter.h"
  26 #include "error.h"
  27 #include <mad.h>
  28 #include "string.h"
  29
  30 /** the output buffer size */
  31 #define MP3_OUTBUF_SIZE 128 * 1024
  32
  33 /** \cond a helper macro */
  34 #define MAD_TO_SHORT(f) (f) >= MAD_F_ONE?  SHRT_MAX :\
  35         (f) <= -MAD_F_ONE? -SHRT_MAX : (signed short) ((f) >> (MAD_F_FRACBITS - 15))
  36 /** \endcond */
  37
  38 /**
  39  * data specific to the mp3dec filter
  40  *
  41  * \sa filter, filter_node
  42  */
  43 struct private_mp3dec_data {
  44         /** information on the current mp3 stream */
  45         struct mad_stream stream;
  46         /** information about the frame which is currently decoded */
  47         struct mad_frame frame;
  48         /** contains the PCM output */
  49         struct mad_synth synth;
  50 };
  51
  52 static ssize_t mp3dec(char *inbuffer, size_t len, struct filter_node *fn)
  53 {
  54         int i, ret;
  55         struct private_mp3dec_data *pmd = fn->private_data;
  56         size_t copy = MIN(len, 4096);
  57
  58         if (fn->loaded > fn->bufsize * 4 / 5)
  59                 return 0;
  60         mad_stream_buffer(&pmd->stream, (unsigned char *) inbuffer, copy);
  61         pmd->stream.error = 0;
  62 next_frame:
  63         ret = mad_frame_decode(&pmd->frame, &pmd->stream);
  64         if (ret) {
  65                 if (MAD_RECOVERABLE(pmd->stream.error) || pmd->stream.error == MAD_ERROR_BUFLEN)
  66                         goto out;
  67                 PARA_ERROR_LOG("fatal: ret = %d, loaded = %d\n", ret, fn->loaded);
  68                 return -E_MAD_FRAME_DECODE;
  69         }
  70         mad_synth_frame(&pmd->synth, &pmd->frame);
  71         fn->fci->samplerate = pmd->frame.header.samplerate;
  72         fn->fci->channels = MAD_NCHANNELS(&pmd->frame.header);
  73
  74         for (i = 0; i < pmd->synth.pcm.length; i++) {
  75                 /* output format: unsigned 16 bit little endian */
  76                 signed short s = MAD_TO_SHORT(pmd->synth.pcm.samples[0][i]);
  77                 fn->buf[fn->loaded++] = s & 0xff;
  78                 fn->buf[fn->loaded++] = s >> 8;
  79                 if (MAD_NCHANNELS(&pmd->frame.header) == 2) { /* stereo */
  80                         s = MAD_TO_SHORT(pmd->synth.pcm.samples[1][i]);
  81                         fn->buf[fn->loaded++] = s & 0xff;
  82                         fn->buf[fn->loaded++] = s >> 8;
  83                 }
  84                 if (fn->loaded != fn->bufsize) /* output buffer not full */
  85                         continue;
  86                 PARA_ERROR_LOG("output buffer full: %d\n", fn->loaded);
  87                         return -E_MP3DEC_OVERRUN;
  88         }
  89         if (fn->loaded <= fn->bufsize * 4 / 5)
  90                 goto next_frame;
  91 out:
  92         if (pmd->stream.next_frame) { /* we still have some data */
  93                 size_t off = pmd->stream.bufend - pmd->stream.next_frame;
  94                 PARA_DEBUG_LOG("converted %d, %d input bytes, %d output bytes\n",
  95                         len - off, off, fn->loaded);
  96                 return copy - off;
  97         }
  98         return copy;
  99 }
 100
 101 static void mp3dec_close(struct filter_node *fn)
 102 {
 103         struct private_mp3dec_data *pmd = fn->private_data;
 104
 105         mad_synth_finish(&pmd->synth);
 106         mad_frame_finish(&pmd->frame);
 107         mad_stream_finish(&pmd->stream);
 108
 109         free(fn->buf);
 110         fn->buf = NULL;
 111         free(pmd);
 112         fn->private_data = NULL;
 113 }
 114
 115 static void mp3dec_open(struct filter_node *fn)
 116 {
 117         fn->private_data = para_calloc(sizeof(struct private_mp3dec_data));
 118         struct private_mp3dec_data *pmd = fn->private_data;
 119
 120         mad_stream_init(&pmd->stream);
 121         mad_frame_init(&pmd->frame);
 122         mad_synth_init(&pmd->synth);
 123         fn->loaded = 0;
 124         fn->bufsize = MP3_OUTBUF_SIZE;
 125         fn->buf = para_calloc(fn->bufsize);
 126 }
 127 /**
 128  * the init function of the mp3dec filter
 129  *
 130  * \sa filter::init
 131  */
 132 void mp3dec_init(struct filter *f)
 133 {
 134         f->open = mp3dec_open;
 135         f->convert = mp3dec;
 136         f->close = mp3dec_close;
 137 }