libmpcodecs/ad_libmad.c

   1 /*
   2  * This file is part of MPlayer.
   3  *
   4  * MPlayer 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  * MPlayer 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 along
  15  * with MPlayer; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <unistd.h>
  22
  23 #include "config.h"
  24
  25 #include "ad_internal.h"
  26
  27 static const ad_info_t info = {
  28         "libmad mpeg audio decoder",
  29         "libmad",
  30         "A'rpi",
  31         "libmad...",
  32         "based on Xine's libmad/xine_decoder.c"
  33 };
  34
  35 LIBAD_EXTERN(libmad)
  36
  37 #include <mad.h>
  38
  39 typedef struct mad_decoder_s {
  40
  41   struct mad_synth  synth;
  42   struct mad_stream stream;
  43   struct mad_frame  frame;
  44
  45   int have_frame;
  46
  47   int               output_sampling_rate;
  48   int               output_open;
  49   int               output_mode;
  50
  51 } mad_decoder_t;
  52
  53 static int preinit(sh_audio_t *sh){
  54
  55   mad_decoder_t *this = malloc(sizeof(mad_decoder_t));
  56   memset(this,0,sizeof(mad_decoder_t));
  57   sh->context = this;
  58
  59   mad_synth_init  (&this->synth);
  60   mad_stream_init (&this->stream);
  61   mad_frame_init  (&this->frame);
  62
  63   sh->audio_out_minsize=2*4608;
  64   sh->audio_in_minsize=4096;
  65
  66   return 1;
  67 }
  68
  69 static int read_frame(sh_audio_t *sh){
  70   mad_decoder_t *this = (mad_decoder_t *) sh->context;
  71   int len;
  72
  73 while((len=demux_read_data(sh->ds,&sh->a_in_buffer[sh->a_in_buffer_len],
  74           sh->a_in_buffer_size-sh->a_in_buffer_len))>0){
  75   sh->a_in_buffer_len+=len;
  76   while(1){
  77     int ret;
  78     mad_stream_buffer (&this->stream, sh->a_in_buffer, sh->a_in_buffer_len);
  79     ret=mad_frame_decode (&this->frame, &this->stream);
  80     if (this->stream.next_frame) {
  81         int num_bytes =
  82             (char*)sh->a_in_buffer+sh->a_in_buffer_len - (char*)this->stream.next_frame;
  83         memmove(sh->a_in_buffer, this->stream.next_frame, num_bytes);
  84         mp_msg(MSGT_DECAUDIO,MSGL_DBG2,"libmad: %d bytes processed\n",sh->a_in_buffer_len-num_bytes);
  85         sh->a_in_buffer_len = num_bytes;
  86     }
  87     if (ret == 0) return 1; // OK!!!
  88     // error! try to resync!
  89     if(this->stream.error==MAD_ERROR_BUFLEN) break;
  90   }
  91 }
  92 mp_msg(MSGT_DECAUDIO,MSGL_INFO,"Cannot sync MAD frame\n");
  93 return 0;
  94 }
  95
  96 static int init(sh_audio_t *sh){
  97   mad_decoder_t *this = (mad_decoder_t *) sh->context;
  98
  99   this->have_frame=read_frame(sh);
 100   if(!this->have_frame) return 0; // failed to sync...
 101
 102   sh->channels=(this->frame.header.mode == MAD_MODE_SINGLE_CHANNEL) ? 1 : 2;
 103   sh->samplerate=this->frame.header.samplerate;
 104   sh->i_bps=this->frame.header.bitrate/8;
 105   sh->samplesize=2;
 106
 107   return 1;
 108 }
 109
 110 static void uninit(sh_audio_t *sh){
 111   mad_decoder_t *this = (mad_decoder_t *) sh->context;
 112   mad_synth_finish (&this->synth);
 113   mad_frame_finish (&this->frame);
 114   mad_stream_finish(&this->stream);
 115   free(sh->context);
 116 }
 117
 118 /* utility to scale and round samples to 16 bits */
 119 static inline signed int scale(mad_fixed_t sample) {
 120   /* round */
 121   sample += (1L << (MAD_F_FRACBITS - 16));
 122
 123   /* clip */
 124   if (sample >= MAD_F_ONE)
 125     sample = MAD_F_ONE - 1;
 126   else if (sample < -MAD_F_ONE)
 127     sample = -MAD_F_ONE;
 128
 129   /* quantize */
 130   return sample >> (MAD_F_FRACBITS + 1 - 16);
 131 }
 132
 133 static int decode_audio(sh_audio_t *sh,unsigned char *buf,int minlen,int maxlen){
 134   mad_decoder_t *this = (mad_decoder_t *) sh->context;
 135   int len=0;
 136
 137   while(len<minlen && len+4608<=maxlen){
 138     if(!this->have_frame) this->have_frame=read_frame(sh);
 139     if(!this->have_frame) break; // failed to sync... or EOF
 140     this->have_frame=0;
 141
 142     mad_synth_frame (&this->synth, &this->frame);
 143
 144         { unsigned int         nchannels, nsamples;
 145           mad_fixed_t const   *left_ch, *right_ch;
 146           struct mad_pcm      *pcm = &this->synth.pcm;
 147           uint16_t            *output = (uint16_t*) buf;
 148
 149           nchannels = pcm->channels;
 150           nsamples  = pcm->length;
 151           left_ch   = pcm->samples[0];
 152           right_ch  = pcm->samples[1];
 153
 154           len+=2*nchannels*nsamples;
 155           buf+=2*nchannels*nsamples;
 156
 157           while (nsamples--) {
 158             /* output sample(s) in 16-bit signed little-endian PCM */
 159
 160             *output++ = scale(*left_ch++);
 161
 162             if (nchannels == 2)
 163               *output++ = scale(*right_ch++);
 164
 165           }
 166         }
 167   }
 168
 169   return len?len:-1;
 170 }
 171
 172 static int control(sh_audio_t *sh,int cmd,void* arg, ...){
 173   mad_decoder_t *this = (mad_decoder_t *) sh->context;
 174     // various optional functions you MAY implement:
 175     switch(cmd){
 176       case ADCTRL_RESYNC_STREAM:
 177         this->have_frame=0;
 178         mad_synth_init  (&this->synth);
 179         mad_stream_init (&this->stream);
 180         mad_frame_init  (&this->frame);
 181         return CONTROL_TRUE;
 182       case ADCTRL_SKIP_FRAME:
 183         this->have_frame=read_frame(sh);
 184         return CONTROL_TRUE;
 185     }
 186   return CONTROL_UNKNOWN;
 187 }