mp3 header parser

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@2589 b3059339-0415-0410-9bf9-f77b7e298cf2

2 files changed, 93 insertions, 1 deletions

diff --git a/libmpdemux/Makefile b/libmpdemux/Makefile
index 0a2019834f..4e4b8e26ad 100644
--- a/libmpdemux/Makefile
+++ b/libmpdemux/Makefile
@@ -3,7 +3,7 @@ LIBNAME = libmpdemux.a
 
 include ../config.mak
 
-SRCS = video.c mpeg_hdr.c cache2.c asfheader.c aviheader.c aviprint.c aviwrite.c demux_asf.c demux_avi.c demux_mov.c demux_mpg.c demuxer.c dvdauth.c open.c parse_es.c stream.c
+SRCS = mp3_hdr.c video.c mpeg_hdr.c cache2.c asfheader.c aviheader.c aviprint.c aviwrite.c demux_asf.c demux_avi.c demux_mov.c demux_mpg.c demuxer.c dvdauth.c open.c parse_es.c stream.c
 ifeq ($(STREAMING),yes)
 SRCS += asf_streaming.c url.c http.c network.c
 endif
diff --git a/libmpdemux/mp3_hdr.c b/libmpdemux/mp3_hdr.c
new file mode 100644
index 0000000000..1db1662eea
--- /dev/null
+++ b/libmpdemux/mp3_hdr.c
@@ -0,0 +1,92 @@
+#include <stdio.h>
+
+#include "config.h"
+#include "mpeg_hdr.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,},
+     {0,32,48,56, 64, 80, 96,112,128,160,192,224,256,320,384,},
+     {0,32,40,48, 56, 64, 80, 96,112,128,160,192,224,256,320,} },
+
+   { {0,32,48,56,64,80,96,112,128,144,160,176,192,224,256,},
+     {0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,},
+     {0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,} }
+};
+static long freqs[9] = { 44100, 48000, 32000, 22050, 24000, 16000 , 11025 , 12000 , 8000 };
+
+/*
+ * return frame size or -1 (bad frame)
+ */
+int mp_decode_mp3_header(unsigned char* hbuf){
+    int stereo,ssize,crc,lsf,mpeg25,framesize,padding,bitrate_index,sampling_frequency;
+    unsigned long newhead = 
+      hbuf[0] << 24 |
+      hbuf[1] << 16 |
+      hbuf[2] <<  8 |
+      hbuf[3];
+
+//    printf("head=0x%08X\n",newhead);
+
+#if 1
+    // head_check:
+    if( (newhead & 0xffe00000) != 0xffe00000 ||  
+        (newhead & 0x0000fc00) == 0x0000fc00){
+	printf("head_check failed\n");
+	return -1;
+    }
+#endif
+
+    if((4-((newhead>>17)&3))!=3){ printf("not layer-3\n"); return -1;}
+
+    if( newhead & ((long)1<<20) ) {
+      lsf = (newhead & ((long)1<<19)) ? 0x0 : 0x1;
+      mpeg25 = 0;
+    } else {
+      lsf = 1;
+      mpeg25 = 1;
+    }
+
+    if(mpeg25)
+      sampling_frequency = 6 + ((newhead>>10)&0x3);
+    else
+      sampling_frequency = ((newhead>>10)&0x3) + (lsf*3);
+
+    if(sampling_frequency>8){
+	printf("invalid sampling_frequency\n");
+	return -1;  // valid: 0..8
+    }
+
+    crc = ((newhead>>16)&0x1)^0x1;
+    bitrate_index = ((newhead>>12)&0xf);
+    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;
+
+    if(!bitrate_index){
+      fprintf(stderr,"Free format not supported.\n");
+      return -1;
+    }
+
+    if(lsf)
+      ssize = (stereo == 1) ? 9 : 17;
+    else
+      ssize = (stereo == 1) ? 17 : 32;
+    if(crc) ssize += 2;
+
+    framesize  = (long) tabsel_123[lsf][2][bitrate_index] * 144000;
+    framesize /= freqs[sampling_frequency]<<lsf;
+    framesize += padding;
+
+//    if(framesize<=0 || framesize>MAXFRAMESIZE) return FALSE;
+
+    return framesize;
+}
+