mp3dec.c

   1 /*
   2  * Copyright (C) 2005-2007 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file mp3dec.c paraslash's mp3 decoder */
   8
   9 #include "para.h"
  10 #include "list.h"
  11 #include "sched.h"
  12 #include "filter.h"
  13 #include "error.h"
  14 #include <mad.h>
  15 #include "string.h"
  16
  17 /** the output buffer size */
  18 #define MP3_OUTBUF_SIZE 128 * 1024
  19
  20 /** \cond a helper macro */
  21 #define MAD_TO_SHORT(f) (f) >= MAD_F_ONE? SHRT_MAX :\
  22         (f) <= -MAD_F_ONE? -SHRT_MAX : (signed short) ((f) >> (MAD_F_FRACBITS - 15))
  23 /** \endcond */
  24
  25 /**
  26  * data specific to the mp3dec filter
  27  *
  28  * \sa filter, filter_node
  29  */
  30 struct private_mp3dec_data {
  31         /** information on the current mp3 stream */
  32         struct mad_stream stream;
  33         /** information about the frame which is currently decoded */
  34         struct mad_frame frame;
  35         /** contains the PCM output */
  36         struct mad_synth synth;
  37 };
  38
  39 static ssize_t mp3dec(char *inbuffer, size_t len, struct filter_node *fn)
  40 {
  41         int i, ret;
  42         struct private_mp3dec_data *pmd = fn->private_data;
  43         size_t copy = PARA_MIN(len, 4096);
  44
  45         if (fn->loaded > fn->bufsize * 4 / 5)
  46                 return 0;
  47         mad_stream_buffer(&pmd->stream, (unsigned char *) inbuffer, copy);
  48         pmd->stream.error = 0;
  49 next_frame:
  50         ret = mad_header_decode(&pmd->frame.header, &pmd->stream);
  51         if (ret < 0)
  52                 goto out;
  53         fn->fc->samplerate = pmd->frame.header.samplerate;
  54         fn->fc->channels = MAD_NCHANNELS(&pmd->frame.header);
  55         ret = mad_frame_decode(&pmd->frame, &pmd->stream);
  56         if (ret) {
  57                 if (MAD_RECOVERABLE(pmd->stream.error) || pmd->stream.error == MAD_ERROR_BUFLEN)
  58                         goto out;
  59                 PARA_ERROR_LOG("fatal: ret = %d, loaded = %zd\n", ret, fn->loaded);
  60                 return -E_MAD_FRAME_DECODE;
  61         }
  62         mad_synth_frame(&pmd->synth, &pmd->frame);
  63
  64         for (i = 0; i < pmd->synth.pcm.length; i++) {
  65                 int s = MAD_TO_SHORT(pmd->synth.pcm.samples[0][i]);
  66                 write_int16_host_endian(fn->buf + fn->loaded, s);
  67                 fn->loaded += 2;
  68                 if (MAD_NCHANNELS(&pmd->frame.header) == 2) { /* stereo */
  69                         s = MAD_TO_SHORT(pmd->synth.pcm.samples[1][i]);
  70                         write_int16_host_endian(fn->buf + fn->loaded, s);
  71                         fn->loaded += 2;
  72                 }
  73                 if (fn->loaded != fn->bufsize) /* output buffer not full */
  74                         continue;
  75                 PARA_ERROR_LOG("output buffer full: %zd\n", fn->loaded);
  76                         return -E_MP3DEC_OVERRUN;
  77         }
  78         if (fn->loaded <= fn->bufsize * 4 / 5)
  79                 goto next_frame;
  80 out:
  81         if (pmd->stream.next_frame) { /* we still have some data */
  82                 size_t off = pmd->stream.bufend - pmd->stream.next_frame;
  83 //              PARA_INFO_LOG("off: %zd, rate: %u, returning %zd\n", off,
  84 //                      fn->fc->samplerate, copy - off);
  85                 return copy - off;
  86         }
  87         return copy;
  88 }
  89
  90 static void mp3dec_close(struct filter_node *fn)
  91 {
  92         struct private_mp3dec_data *pmd = fn->private_data;
  93
  94         mad_synth_finish(&pmd->synth);
  95         mad_frame_finish(&pmd->frame);
  96         mad_stream_finish(&pmd->stream);
  97
  98         free(fn->buf);
  99         fn->buf = NULL;
 100         free(pmd);
 101         fn->private_data = NULL;
 102 }
 103
 104 static void mp3dec_open(struct filter_node *fn)
 105 {
 106         fn->private_data = para_calloc(sizeof(struct private_mp3dec_data));
 107         struct private_mp3dec_data *pmd = fn->private_data;
 108
 109         mad_stream_init(&pmd->stream);
 110         mad_frame_init(&pmd->frame);
 111         mad_synth_init(&pmd->synth);
 112         fn->loaded = 0;
 113         fn->bufsize = MP3_OUTBUF_SIZE;
 114         fn->buf = para_calloc(fn->bufsize);
 115 }
 116
 117 /**
 118  * the init function of the mp3dec filter
 119  *
 120  * \param f pointer to the filter struct to initialize
 121  *
 122  * \sa filter::init
 123  */
 124 void mp3dec_init(struct filter *f)
 125 {
 126         f->open = mp3dec_open;
 127         f->convert = mp3dec;
 128         f->close = mp3dec_close;
 129 }