mp3dec.c

   1 /*
   2  * Copyright (C) 2005-2008 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 /** Convert a sample value from libmad to a signed short. */
  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
  24 /** Data specific to the mp3dec filter. */
  25 struct private_mp3dec_data {
  26         /** Information on the current mp3 stream. */
  27         struct mad_stream stream;
  28         /** Information about the frame which is currently decoded. */
  29         struct mad_frame frame;
  30         /** Contains the PCM output. */
  31         struct mad_synth synth;
  32 };
  33
  34 static ssize_t mp3dec(char *inbuffer, size_t len, struct filter_node *fn)
  35 {
  36         int i, ret;
  37         struct private_mp3dec_data *pmd = fn->private_data;
  38         size_t copy = PARA_MIN(len, 4096);
  39
  40         if (fn->loaded > fn->bufsize * 4 / 5)
  41                 return 0;
  42         mad_stream_buffer(&pmd->stream, (unsigned char *) inbuffer, copy);
  43         pmd->stream.error = 0;
  44 next_frame:
  45         ret = mad_header_decode(&pmd->frame.header, &pmd->stream);
  46         if (ret < 0) {
  47                 if (pmd->stream.error != MAD_ERROR_BUFLEN &&
  48                         pmd->stream.error != MAD_ERROR_LOSTSYNC)
  49                         PARA_DEBUG_LOG("header decode: %s\n",
  50                                 mad_stream_errorstr(&pmd->stream));
  51                 goto out;
  52         }
  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) ||
  58                         pmd->stream.error == MAD_ERROR_BUFLEN) {
  59                         PARA_DEBUG_LOG("frame decode: %s\n",
  60                                 mad_stream_errorstr(&pmd->stream));
  61                         goto out;
  62                 }
  63                 PARA_ERROR_LOG("frame decode: %s\n",
  64                         mad_stream_errorstr(&pmd->stream));
  65                 return -E_MAD_FRAME_DECODE;
  66         }
  67         mad_synth_frame(&pmd->synth, &pmd->frame);
  68
  69         for (i = 0; i < pmd->synth.pcm.length; i++) {
  70                 int s = MAD_TO_SHORT(pmd->synth.pcm.samples[0][i]);
  71                 write_int16_host_endian(fn->buf + fn->loaded, s);
  72                 fn->loaded += 2;
  73                 if (MAD_NCHANNELS(&pmd->frame.header) == 2) { /* stereo */
  74                         s = MAD_TO_SHORT(pmd->synth.pcm.samples[1][i]);
  75                         write_int16_host_endian(fn->buf + fn->loaded, s);
  76                         fn->loaded += 2;
  77                 }
  78                 if (fn->loaded != fn->bufsize) /* output buffer not full */
  79                         continue;
  80                 PARA_ERROR_LOG("output buffer full: %zd\n", fn->loaded);
  81                         return -E_MP3DEC_OVERRUN;
  82         }
  83         if (fn->loaded <= fn->bufsize * 4 / 5)
  84                 goto next_frame;
  85 out:
  86         if (pmd->stream.next_frame) { /* we still have some data */
  87                 size_t off = pmd->stream.bufend - pmd->stream.next_frame;
  88 //              PARA_INFO_LOG("off: %zd, rate: %u, returning %zd\n", off,
  89 //                      fn->fc->samplerate, copy - off);
  90                 return copy - off;
  91         }
  92         return copy;
  93 }
  94
  95 static void mp3dec_close(struct filter_node *fn)
  96 {
  97         struct private_mp3dec_data *pmd = fn->private_data;
  98
  99         mad_synth_finish(&pmd->synth);
 100         mad_frame_finish(&pmd->frame);
 101         mad_stream_finish(&pmd->stream);
 102
 103         free(fn->buf);
 104         fn->buf = NULL;
 105         free(pmd);
 106         fn->private_data = NULL;
 107 }
 108
 109 static void mp3dec_open(struct filter_node *fn)
 110 {
 111         struct private_mp3dec_data *pmd = para_calloc(sizeof(*pmd));
 112
 113         fn->private_data = pmd;
 114         mad_stream_init(&pmd->stream);
 115         mad_frame_init(&pmd->frame);
 116         mad_synth_init(&pmd->synth);
 117         fn->loaded = 0;
 118         fn->bufsize = MP3_OUTBUF_SIZE;
 119         fn->buf = para_calloc(fn->bufsize);
 120 }
 121
 122 /**
 123  * The init function of the mp3dec filter.
 124  *
 125  * \param f Pointer to the filter struct to initialize.
 126  *
 127  * \sa filter::init.
 128  */
 129 void mp3dec_filter_init(struct filter *f)
 130 {
 131         f->open = mp3dec_open;
 132         f->convert = mp3dec;
 133         f->close = mp3dec_close;
 134 }