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 /** 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                 goto out;
  48         fn->fc->samplerate = pmd->frame.header.samplerate;
  49         fn->fc->channels = MAD_NCHANNELS(&pmd->frame.header);
  50         ret = mad_frame_decode(&pmd->frame, &pmd->stream);
  51         if (ret) {
  52                 if (MAD_RECOVERABLE(pmd->stream.error) || pmd->stream.error == MAD_ERROR_BUFLEN)
  53                         goto out;
  54                 PARA_ERROR_LOG("fatal: ret = %d, loaded = %zd\n", ret, fn->loaded);
  55                 return -E_MAD_FRAME_DECODE;
  56         }
  57         mad_synth_frame(&pmd->synth, &pmd->frame);
  58
  59         for (i = 0; i < pmd->synth.pcm.length; i++) {
  60                 int s = MAD_TO_SHORT(pmd->synth.pcm.samples[0][i]);
  61                 write_int16_host_endian(fn->buf + fn->loaded, s);
  62                 fn->loaded += 2;
  63                 if (MAD_NCHANNELS(&pmd->frame.header) == 2) { /* stereo */
  64                         s = MAD_TO_SHORT(pmd->synth.pcm.samples[1][i]);
  65                         write_int16_host_endian(fn->buf + fn->loaded, s);
  66                         fn->loaded += 2;
  67                 }
  68                 if (fn->loaded != fn->bufsize) /* output buffer not full */
  69                         continue;
  70                 PARA_ERROR_LOG("output buffer full: %zd\n", fn->loaded);
  71                         return -E_MP3DEC_OVERRUN;
  72         }
  73         if (fn->loaded <= fn->bufsize * 4 / 5)
  74                 goto next_frame;
  75 out:
  76         if (pmd->stream.next_frame) { /* we still have some data */
  77                 size_t off = pmd->stream.bufend - pmd->stream.next_frame;
  78 //              PARA_INFO_LOG("off: %zd, rate: %u, returning %zd\n", off,
  79 //                      fn->fc->samplerate, copy - off);
  80                 return copy - off;
  81         }
  82         return copy;
  83 }
  84
  85 static void mp3dec_close(struct filter_node *fn)
  86 {
  87         struct private_mp3dec_data *pmd = fn->private_data;
  88
  89         mad_synth_finish(&pmd->synth);
  90         mad_frame_finish(&pmd->frame);
  91         mad_stream_finish(&pmd->stream);
  92
  93         free(fn->buf);
  94         fn->buf = NULL;
  95         free(pmd);
  96         fn->private_data = NULL;
  97 }
  98
  99 static void mp3dec_open(struct filter_node *fn)
 100 {
 101         fn->private_data = para_calloc(sizeof(struct private_mp3dec_data));
 102         struct private_mp3dec_data *pmd = fn->private_data;
 103
 104         mad_stream_init(&pmd->stream);
 105         mad_frame_init(&pmd->frame);
 106         mad_synth_init(&pmd->synth);
 107         fn->loaded = 0;
 108         fn->bufsize = MP3_OUTBUF_SIZE;
 109         fn->buf = para_calloc(fn->bufsize);
 110 }
 111
 112 /**
 113  * The init function of the mp3dec filter.
 114  *
 115  * \param f Pointer to the filter struct to initialize.
 116  *
 117  * \sa filter::init.
 118  */
 119 void mp3dec_init(struct filter *f)
 120 {
 121         f->open = mp3dec_open;
 122         f->convert = mp3dec;
 123         f->close = mp3dec_close;
 124 }