libmpdemux/demux_mpc.c

   1 /**
   2  * Demuxer for Musepack v7 bitstream
   3  * by Reimar Doeffinger <Reimar.Doeffinger@stud.uni-karlsruhe.de>
   4  * This code may be be relicensed under the terms of the GNU LGPL when it
   5  * becomes part of the FFmpeg project (ffmpeg.org)
   6  */
   7
   8 #include "config.h"
   9
  10 #include <stdlib.h>
  11 #include <stdio.h>
  12 #include <string.h>
  13 #include "mp_msg.h"
  14 #include "libavutil/common.h"
  15 #include "mpbswap.h"
  16 #include "stream/stream.h"
  17 #include "demuxer.h"
  18 #include "stheader.h"
  19
  20
  21 #define HDR_SIZE (6 * 4)
  22
  23 typedef struct da_priv {
  24   float last_pts;
  25   float pts_per_packet;
  26   uint32_t dword;
  27   int pos;
  28   float length;
  29 } da_priv_t;
  30
  31 static uint32_t get_bits(da_priv_t* priv, stream_t* s, int bits) {
  32   uint32_t out = priv->dword;
  33   uint32_t mask = (1 << bits) - 1;
  34   priv->pos += bits;
  35   if (priv->pos < 32) {
  36     out >>= (32 - priv->pos);
  37   }
  38   else {
  39     stream_read(s, (void *)&priv->dword, 4);
  40     priv->dword = le2me_32(priv->dword);
  41     priv->pos -= 32;
  42     if (priv->pos) {
  43       out <<= priv->pos;
  44       out |= priv->dword >> (32 - priv->pos);
  45     }
  46   }
  47   return out & mask;
  48 }
  49
  50 static int demux_mpc_check(demuxer_t* demuxer) {
  51   stream_t *s = demuxer->stream;
  52   uint8_t hdr[HDR_SIZE];
  53   int i;
  54
  55   if (stream_read(s, hdr, HDR_SIZE) != HDR_SIZE)
  56     return 0;
  57   for (i = 0; i < 30000 && !s->eof; i++) {
  58     if (hdr[0] == 'M' && hdr[1] == 'P' && hdr[2] == '+')
  59       break;
  60     memmove(hdr, &hdr[1], HDR_SIZE - 1);
  61     stream_read(s, &hdr[HDR_SIZE - 1], 1);
  62   }
  63
  64   if (hdr[0] != 'M' || hdr[1] != 'P' || hdr[2] != '+')
  65     return 0;
  66   demuxer->movi_start = stream_tell(s) - HDR_SIZE;
  67   demuxer->movi_end = s->end_pos;
  68   demuxer->priv = malloc(HDR_SIZE);
  69   memcpy(demuxer->priv, hdr, HDR_SIZE);
  70   return DEMUXER_TYPE_MPC;
  71 }
  72
  73 static demuxer_t *demux_mpc_open(demuxer_t* demuxer) {
  74   float seconds = 0;
  75   stream_t *s = demuxer->stream;
  76   sh_audio_t* sh_audio;
  77   da_priv_t* priv = demuxer->priv;
  78
  79   sh_audio = new_sh_audio(demuxer,0);
  80
  81   {
  82     char *wf = calloc(1, sizeof(WAVEFORMATEX) + HDR_SIZE);
  83     char *header = &wf[sizeof(WAVEFORMATEX)];
  84     const int freqs[4] = {44100, 48000, 37800, 32000};
  85     int frames;
  86     sh_audio->format = mmioFOURCC('M', 'P', 'C', ' ');
  87     memcpy(header, priv, HDR_SIZE);
  88     free(priv);
  89     frames = header[4] | header[5] << 8 | header[6] << 16 | header[7] << 24;
  90     sh_audio->wf = (WAVEFORMATEX *)wf;
  91     sh_audio->wf->wFormatTag = sh_audio->format;
  92     sh_audio->wf->nChannels = 2;
  93     sh_audio->wf->nSamplesPerSec = freqs[header[10] & 3];
  94     sh_audio->wf->nBlockAlign = 32 * 36;
  95     sh_audio->wf->wBitsPerSample = 16;
  96     seconds = 1152 * frames / (float)sh_audio->wf->nSamplesPerSec;
  97     if (demuxer->movi_end > demuxer->movi_start && seconds > 1)
  98       sh_audio->wf->nAvgBytesPerSec = (demuxer->movi_end - demuxer->movi_start) / seconds;
  99     else
 100       sh_audio->wf->nAvgBytesPerSec = 32 * 1024; // dummy to make mencoder not hang
 101     sh_audio->wf->cbSize = HDR_SIZE;
 102     demuxer->movi_start = stream_tell(s);
 103     demuxer->movi_end = s->end_pos;
 104   }
 105
 106   priv = malloc(sizeof(da_priv_t));
 107   priv->last_pts = -1;
 108   priv->pts_per_packet = (32 * 36) / (float)sh_audio->wf->nSamplesPerSec;
 109   priv->length = seconds;
 110   priv->dword = 0;
 111   priv->pos = 32; // empty bit buffer
 112   get_bits(priv, s, 8); // discard first 8 bits
 113   demuxer->priv = priv;
 114   demuxer->audio->id = 0;
 115   demuxer->audio->sh = sh_audio;
 116   sh_audio->ds = demuxer->audio;
 117   sh_audio->samplerate = sh_audio->wf->nSamplesPerSec;
 118   sh_audio->i_bps = sh_audio->wf->nAvgBytesPerSec;
 119   sh_audio->audio.dwSampleSize = 0;
 120   sh_audio->audio.dwScale = 32 * 36;
 121   sh_audio->audio.dwRate = sh_audio->samplerate;
 122
 123   return demuxer;
 124 }
 125
 126 static int demux_mpc_fill_buffer(demuxer_t *demux, demux_stream_t *ds) {
 127   int l;
 128   int bit_len;
 129   demux_packet_t* dp;
 130   sh_audio_t* sh_audio = ds->sh;
 131   da_priv_t* priv = demux->priv;
 132   stream_t* s = demux->stream;
 133   sh_audio = ds->sh;
 134
 135   if (s->eof)
 136     return 0;
 137
 138   bit_len = get_bits(priv, s, 20);
 139   dp = new_demux_packet((bit_len + 7) / 8);
 140   for (l = 0; l < (bit_len / 8); l++)
 141     dp->buffer[l] = get_bits(priv, s, 8);
 142   bit_len %= 8;
 143   if (bit_len)
 144     dp->buffer[l] = get_bits(priv, s, bit_len) << (8 - bit_len);
 145   if (priv->last_pts < 0)
 146     priv->last_pts = 0;
 147   else
 148     priv->last_pts += priv->pts_per_packet;
 149   dp->pts = priv->last_pts;
 150   ds_add_packet(ds, dp);
 151   return 1;
 152 }
 153
 154 static void demux_mpc_seek(demuxer_t *demuxer,float rel_seek_secs,float audio_delay,int flags){
 155   sh_audio_t* sh_audio = demuxer->audio->sh;
 156   da_priv_t* priv = demuxer->priv;
 157   stream_t* s = demuxer->stream;
 158   float target = rel_seek_secs;
 159   if (flags & 2)
 160     target *= priv->length;
 161   if (!(flags & 1))
 162     target += priv->last_pts;
 163   if (target < priv->last_pts) {
 164     stream_seek(s, demuxer->movi_start);
 165     priv->pos = 32; // empty bit buffer
 166     get_bits(priv, s, 8); // discard first 8 bits
 167     priv->last_pts = 0;
 168   }
 169   while (target > priv->last_pts) {
 170     int bit_len = get_bits(priv, s, 20);
 171     if (bit_len > 32) {
 172       stream_skip(s, bit_len / 32 * 4 - 4);
 173       get_bits(priv, s, 32); // make sure dword is reloaded
 174     }
 175     get_bits(priv, s, bit_len % 32);
 176     priv->last_pts += priv->pts_per_packet;
 177     if (s->eof) break;
 178   }
 179   if (!sh_audio) return;
 180 }
 181
 182 static void demux_close_mpc(demuxer_t* demuxer) {
 183   da_priv_t* priv = demuxer->priv;
 184
 185   if(!priv)
 186     return;
 187   free(priv);
 188 }
 189
 190 static int demux_mpc_control(demuxer_t *demuxer,int cmd, void *arg){
 191   da_priv_t* priv = demuxer->priv;
 192   switch (cmd) {
 193     case DEMUXER_CTRL_GET_TIME_LENGTH:
 194       if (priv->length < 1) return DEMUXER_CTRL_DONTKNOW;
 195       *((double *)arg) = priv->length;
 196       return DEMUXER_CTRL_OK;
 197     case DEMUXER_CTRL_GET_PERCENT_POS:
 198       if (priv->length < 1) return DEMUXER_CTRL_DONTKNOW;
 199       *((int *)arg) = priv->last_pts * 100 / priv->length;
 200       return DEMUXER_CTRL_OK;
 201   }
 202   return DEMUXER_CTRL_NOTIMPL;
 203 }
 204
 205
 206 demuxer_desc_t demuxer_desc_mpc = {
 207   "Musepack demuxer",
 208   "mpc",
 209   "MPC",
 210   "Reza Jelveh, Reimar Doeffinger",
 211   "supports v7 bitstream only",
 212   DEMUXER_TYPE_MPC,
 213   0, // unsafe autodetect
 214   demux_mpc_check,
 215   demux_mpc_fill_buffer,
 216   demux_mpc_open,
 217   demux_close_mpc,
 218   demux_mpc_seek,
 219   demux_mpc_control
 220 };