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-rw-r--r--demux/mp3_hdr.c144
1 files changed, 144 insertions, 0 deletions
diff --git a/demux/mp3_hdr.c b/demux/mp3_hdr.c
new file mode 100644
index 0000000000..a4834f4f81
--- /dev/null
+++ b/demux/mp3_hdr.c
@@ -0,0 +1,144 @@
+/*
+ * This file is part of MPlayer.
+ *
+ * MPlayer is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * MPlayer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with MPlayer; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <stdio.h>
+
+#include "config.h"
+#include "mp3_hdr.h"
+#include "mp_msg.h"
+
+//----------------------- mp3 audio frame header parser -----------------------
+
+static int tabsel_123[2][3][16] = {
+ { {0,32,64,96,128,160,192,224,256,288,320,352,384,416,448,0},
+ {0,32,48,56, 64, 80, 96,112,128,160,192,224,256,320,384,0},
+ {0,32,40,48, 56, 64, 80, 96,112,128,160,192,224,256,320,0} },
+
+ { {0,32,48,56,64,80,96,112,128,144,160,176,192,224,256,0},
+ {0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,0},
+ {0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,0} }
+};
+
+static long freqs[9] = { 44100, 48000, 32000, // MPEG 1.0
+ 22050, 24000, 16000, // MPEG 2.0
+ 11025, 12000, 8000}; // MPEG 2.5
+
+/*
+ * return frame size or -1 (bad frame)
+ */
+int mp_get_mp3_header(unsigned char* hbuf,int* chans, int* srate, int* spf, int* mpa_layer, int* br){
+ int stereo,ssize,lsf,framesize,padding,bitrate_index,sampling_frequency, divisor;
+ int bitrate;
+ int layer, mult[3] = { 12000, 144000, 144000 };
+ unsigned long newhead =
+ hbuf[0] << 24 |
+ hbuf[1] << 16 |
+ hbuf[2] << 8 |
+ hbuf[3];
+
+// printf("head=0x%08X\n",newhead);
+
+ // head_check:
+ if( (newhead & 0xffe00000) != 0xffe00000 ){
+ mp_msg(MSGT_DEMUXER,MSGL_DBG2,"head_check failed\n");
+ return -1;
+ }
+
+ layer = 4-((newhead>>17)&3);
+ if(layer==4){
+ mp_msg(MSGT_DEMUXER,MSGL_DBG2,"not layer-1/2/3\n");
+ return -1;
+ }
+
+ sampling_frequency = ((newhead>>10)&0x3); // valid: 0..2
+ if(sampling_frequency==3){
+ mp_msg(MSGT_DEMUXER,MSGL_DBG2,"invalid sampling_frequency\n");
+ return -1;
+ }
+
+ if( newhead & ((long)1<<20) ) {
+ // MPEG 1.0 (lsf==0) or MPEG 2.0 (lsf==1)
+ lsf = (newhead & ((long)1<<19)) ? 0x0 : 0x1;
+ sampling_frequency += (lsf*3);
+ } else {
+ // MPEG 2.5
+ lsf = 1;
+ sampling_frequency += 6;
+ }
+
+// crc = ((newhead>>16)&0x1)^0x1;
+ bitrate_index = ((newhead>>12)&0xf); // valid: 1..14
+ padding = ((newhead>>9)&0x1);
+// fr->extension = ((newhead>>8)&0x1);
+// fr->mode = ((newhead>>6)&0x3);
+// fr->mode_ext = ((newhead>>4)&0x3);
+// fr->copyright = ((newhead>>3)&0x1);
+// fr->original = ((newhead>>2)&0x1);
+// fr->emphasis = newhead & 0x3;
+
+ stereo = ( (((newhead>>6)&0x3)) == 3) ? 1 : 2;
+
+// !checked later through tabsel_123[]!
+// if(!bitrate_index || bitrate_index==15){
+// mp_msg(MSGT_DEMUXER,MSGL_DBG2,"Free format not supported.\n");
+// return -1;
+// }
+
+ if(lsf)
+ ssize = (stereo == 1) ? 9 : 17;
+ else
+ ssize = (stereo == 1) ? 17 : 32;
+ if(!((newhead>>16)&0x1)) ssize += 2; // CRC
+
+ bitrate = tabsel_123[lsf][layer-1][bitrate_index];
+ framesize = bitrate * mult[layer-1];
+
+ mp_msg(MSGT_DEMUXER,MSGL_DBG2,"FRAMESIZE: %d, layer: %d, bitrate: %d, mult: %d\n",
+ framesize, layer, tabsel_123[lsf][layer-1][bitrate_index], mult[layer-1]);
+ if(!framesize){
+ mp_msg(MSGT_DEMUXER,MSGL_DBG2,"invalid framesize/bitrate_index\n");
+ return -1;
+ }
+
+ divisor = (layer == 3 ? (freqs[sampling_frequency] << lsf) : freqs[sampling_frequency]);
+ framesize /= divisor;
+ if(layer==1)
+ framesize = (framesize+padding)*4;
+ else
+ framesize += padding;
+
+// if(framesize<=0 || framesize>MAXFRAMESIZE) return FALSE;
+ if(srate) {
+ *srate = freqs[sampling_frequency];
+ if(spf) {
+ if(layer == 1)
+ *spf = 384;
+ else if(layer == 2)
+ *spf = 1152;
+ else if(*srate < 32000)
+ *spf = 576;
+ else
+ *spf = 1152;
+ }
+ }
+ if(mpa_layer) *mpa_layer = layer;
+ if(chans) *chans = stereo;
+ if(br) *br = bitrate;
+
+ return framesize;
+}