Still more attempts to better find the right mp3 frame header
This commit is contained in:
Ron Pedde
parent
3def3f6e9e
commit
fd70a618d6
|
|
@ -59,6 +59,25 @@
|
|||
* Typedefs
|
||||
*/
|
||||
|
||||
typedef struct tag_scan_frameinfo {
|
||||
int layer;
|
||||
int bitrate;
|
||||
int samplerate;
|
||||
int stereo;
|
||||
|
||||
int frame_length;
|
||||
int crc_protected;
|
||||
int samples_per_frame;
|
||||
int padding;
|
||||
int xing_offset;
|
||||
|
||||
double version;
|
||||
|
||||
int is_cbr;
|
||||
int is_valid;
|
||||
} SCAN_FRAMEINFO;
|
||||
|
||||
|
||||
typedef struct tag_scan_id3header {
|
||||
unsigned char id[3];
|
||||
unsigned char version[2];
|
||||
|
|
@ -1136,6 +1155,135 @@ int scan_get_aacfileinfo(char *file, MP3FILE *pmp3) {
|
|||
}
|
||||
|
||||
|
||||
/**
|
||||
* Decode an mp3 frame header. Determine layer, bitrate,
|
||||
* samplerate, etc, and fill in the passed structure.
|
||||
*
|
||||
* @param frame 4 byte mp3 frame header
|
||||
* @param pfi pointer to an allocated SCAN_FRAMEINFO struct
|
||||
* @return 0 on success (valid frame), -1 otherwise
|
||||
*/
|
||||
int scan_decode_mp3_frame(unsigned char *frame, SCAN_FRAMEINFO *pfi) {
|
||||
int ver;
|
||||
int layer_index;
|
||||
int sample_index;
|
||||
int bitrate_index;
|
||||
int samplerate_index;
|
||||
|
||||
if((frame[0] != 0xFF) || (frame[1] < 224)) {
|
||||
pfi->is_valid=0;
|
||||
return -1;
|
||||
}
|
||||
|
||||
ver=(frame[1] & 0x18) >> 3;
|
||||
pfi->layer = 4 - ((frame[1] & 0x6) >> 1);
|
||||
|
||||
layer_index=-1;
|
||||
sample_index=-1;
|
||||
|
||||
switch(ver) {
|
||||
case 0:
|
||||
pfi->version = 2.5;
|
||||
sample_index=2;
|
||||
if(pfi->layer == 1)
|
||||
layer_index = 3;
|
||||
if((pfi->layer == 2) || (pfi->layer == 3))
|
||||
layer_index = 4;
|
||||
break;
|
||||
case 2:
|
||||
pfi->version = 2.0;
|
||||
sample_index=1;
|
||||
if(pfi->layer == 1)
|
||||
layer_index=3;
|
||||
if((pfi->layer == 2) || (pfi->layer == 3))
|
||||
layer_index=4;
|
||||
break;
|
||||
case 3:
|
||||
pfi->version = 1.0;
|
||||
sample_index=0;
|
||||
if(pfi->layer == 1)
|
||||
layer_index = 0;
|
||||
if(pfi->layer == 2)
|
||||
layer_index = 1;
|
||||
if(pfi->layer == 3)
|
||||
layer_index = 2;
|
||||
break;
|
||||
}
|
||||
|
||||
if((layer_index < 0) || (layer_index > 4)) {
|
||||
pfi->is_valid=0;
|
||||
return -1;
|
||||
}
|
||||
|
||||
if((sample_index < 0) || (sample_index > 2)) {
|
||||
pfi->is_valid=0;
|
||||
return -1;
|
||||
}
|
||||
|
||||
if(pfi->layer==1) pfi->samples_per_frame=384;
|
||||
if(pfi->layer==2) pfi->samples_per_frame=1152;
|
||||
if(pfi->layer==3) {
|
||||
if(pfi->version == 1.0) {
|
||||
pfi->samples_per_frame=1152;
|
||||
} else {
|
||||
pfi->samples_per_frame=576;
|
||||
}
|
||||
}
|
||||
|
||||
bitrate_index=(frame[2] & 0xF0) >> 4;
|
||||
samplerate_index=(frame[2] & 0x0C) >> 2;
|
||||
|
||||
if(bitrate_index == 0xF) {
|
||||
pfi->is_valid=0;
|
||||
return -1;
|
||||
}
|
||||
|
||||
if(samplerate_index == 3) {
|
||||
pfi->is_valid=0;
|
||||
return -1;
|
||||
}
|
||||
|
||||
pfi->bitrate = scan_br_table[layer_index][bitrate_index];
|
||||
pfi->samplerate = scan_sample_table[sample_index][samplerate_index];
|
||||
|
||||
if((frame[3] & 0xC0 >> 6) == 3)
|
||||
pfi->stereo = 0;
|
||||
else
|
||||
pfi->stereo = 1;
|
||||
|
||||
if(frame[2] & 0x02) { /* Padding bit set */
|
||||
pfi->padding=1;
|
||||
} else {
|
||||
pfi->padding=0;
|
||||
}
|
||||
|
||||
if(pfi->version == 1.0) {
|
||||
if(pfi->stereo) {
|
||||
pfi->xing_offset=32;
|
||||
} else {
|
||||
pfi->xing_offset=17;
|
||||
}
|
||||
} else {
|
||||
if(pfi->stereo) {
|
||||
pfi->xing_offset=17;
|
||||
} else {
|
||||
pfi->xing_offset=9;
|
||||
}
|
||||
}
|
||||
|
||||
pfi->crc_protected=(frame[1] & 0xFE);
|
||||
|
||||
if(pfi->layer == 1) {
|
||||
pfi->frame_length = (12 * pfi->bitrate * 1000 / pfi->samplerate + pfi->padding) * 4;
|
||||
} else {
|
||||
pfi->frame_length = 144 * pfi->bitrate * 1000 / pfi->samplerate + pfi->padding;
|
||||
}
|
||||
|
||||
pfi->is_valid=1;
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* scan_get_mp3fileinfo
|
||||
*
|
||||
|
|
@ -1145,26 +1293,15 @@ int scan_get_aacfileinfo(char *file, MP3FILE *pmp3) {
|
|||
int scan_get_mp3fileinfo(char *file, MP3FILE *pmp3) {
|
||||
FILE *infile;
|
||||
SCAN_ID3HEADER *pid3;
|
||||
SCAN_FRAMEINFO fi;
|
||||
unsigned int size=0;
|
||||
off_t fp_size=0;
|
||||
off_t file_size;
|
||||
unsigned char buffer[1024];
|
||||
int index;
|
||||
int layer_index;
|
||||
int sample_index;
|
||||
|
||||
int ver=0;
|
||||
int layer=0;
|
||||
int bitrate=0;
|
||||
int samplerate=0;
|
||||
int stereo=0;
|
||||
|
||||
int padding_bit=0;
|
||||
int padding_bytes=0;
|
||||
int samples_per_frame=0;
|
||||
int frame_size=0;
|
||||
int number_of_frames=0;
|
||||
int xing_offset,xing_flags;
|
||||
int xing_flags;
|
||||
int found;
|
||||
|
||||
if(!(infile=fopen(file,"rb"))) {
|
||||
|
|
@ -1208,9 +1345,8 @@ int scan_get_mp3fileinfo(char *file, MP3FILE *pmp3) {
|
|||
|
||||
index=0;
|
||||
found=0;
|
||||
if((buffer[index] == 0xFF) && (buffer[index+1] >= 224)) {
|
||||
/* good header */
|
||||
} else {
|
||||
|
||||
if(scan_decode_mp3_frame(&buffer[index],&fi)) { /* Bad frame header */
|
||||
DPRINTF(E_DBG,L_SCAN,"Starting brute-force search for frame header\n");
|
||||
|
||||
fp_size=0;
|
||||
|
|
@ -1233,20 +1369,16 @@ int scan_get_mp3fileinfo(char *file, MP3FILE *pmp3) {
|
|||
break; /* read in the next block */
|
||||
}
|
||||
|
||||
if((buffer[index] == 0xFF) && (buffer[index+1] >= 224)) {
|
||||
DPRINTF(E_DBG,L_SCAN,"Possible header at %d\n",index);
|
||||
/* could be valid... sanity check it */
|
||||
|
||||
ver=(buffer[index+1] & 0x18) >> 3;
|
||||
layer=(buffer[index+1] & 0x6) >> 1;
|
||||
bitrate=(buffer[index+2] & 0xF0) >> 4;
|
||||
|
||||
if((ver != 1) && (layer != 0) && (bitrate != 0) && (bitrate !=15)) {
|
||||
DPRINTF(E_DBG,L_SCAN,"Good header\n");
|
||||
fp_size =+ (index + 1);
|
||||
if(!scan_decode_mp3_frame(&buffer[index],&fi)) {
|
||||
DPRINTF(E_DBG,L_SCAN,"valid header at %d\n",index);
|
||||
if(strncasecmp((char*)&buffer[index+fi.xing_offset+4],"XING",4) == 0) {
|
||||
found=1;
|
||||
}
|
||||
|
||||
/* should check next frame... */
|
||||
found=1;
|
||||
}
|
||||
|
||||
if(!found)
|
||||
index++;
|
||||
}
|
||||
|
|
@ -1267,138 +1399,50 @@ int scan_get_mp3fileinfo(char *file, MP3FILE *pmp3) {
|
|||
}
|
||||
*/
|
||||
|
||||
if((buffer[index] == 0xFF)&&(buffer[index+1] >= 224)) {
|
||||
ver=(buffer[index+1] & 0x18) >> 3;
|
||||
layer=(buffer[index+1] & 0x6) >> 1;
|
||||
layer = 4-layer;
|
||||
|
||||
layer_index=-1;
|
||||
sample_index=-1;
|
||||
|
||||
switch(ver) {
|
||||
case 0: /* MPEG Version 2.5 */
|
||||
sample_index=2;
|
||||
if(layer == 1)
|
||||
layer_index=3;
|
||||
else
|
||||
layer_index=4;
|
||||
break;
|
||||
case 2: /* MPEG Version 2 */
|
||||
sample_index=1;
|
||||
if(layer == 1)
|
||||
layer_index=3;
|
||||
else
|
||||
layer_index=4;
|
||||
break;
|
||||
case 3: /* MPEG Version 1 */
|
||||
sample_index=0;
|
||||
if(layer == 1) /* layer 1 */
|
||||
layer_index=0;
|
||||
if(layer == 2) /* layer 2 */
|
||||
layer_index=1;
|
||||
if(layer == 3) /* layer 3 */
|
||||
layer_index=2;
|
||||
break;
|
||||
}
|
||||
|
||||
if((layer_index < 0) || (layer_index > 4)) {
|
||||
DPRINTF(E_LOG,L_SCAN,"Bad mp3 header in %s: bad layer_index\n",file);
|
||||
fclose(infile);
|
||||
return -1;
|
||||
}
|
||||
|
||||
if((sample_index < 0) || (sample_index > 2)) {
|
||||
DPRINTF(E_LOG,L_SCAN,"Bad mp3 header in %s: bad sample_index\n",file);
|
||||
fclose(infile);
|
||||
return -1;
|
||||
}
|
||||
|
||||
if(layer==1) samples_per_frame=384; /* Layer I */
|
||||
if(layer==2) samples_per_frame=1152; /* Layer II */
|
||||
if(layer==3) { /* Layer III */
|
||||
if(ver == 3) { /* MPEG 1 */
|
||||
samples_per_frame=1152;
|
||||
} else {
|
||||
samples_per_frame=576;
|
||||
}
|
||||
}
|
||||
|
||||
bitrate=(buffer[index+2] & 0xF0) >> 4;
|
||||
bitrate=scan_br_table[layer_index][bitrate];
|
||||
samplerate=(buffer[index+2] & 0x0C) >> 2; /* can only be 0-3 */
|
||||
samplerate=scan_sample_table[sample_index][samplerate];
|
||||
pmp3->bitrate=bitrate;
|
||||
pmp3->samplerate=samplerate;
|
||||
stereo=buffer[index+3] & 0xC0 >> 6;
|
||||
if(stereo == 3)
|
||||
stereo=0;
|
||||
else
|
||||
stereo=1;
|
||||
|
||||
padding_bit=(buffer[index+2] & 0x02) >> 1;
|
||||
if(padding_bit) {
|
||||
if(layer == 1)
|
||||
padding_bytes=4;
|
||||
else
|
||||
padding_bytes=1;
|
||||
}
|
||||
|
||||
DPRINTF(E_DBG,L_SCAN," MPEG Version: %s\n",ver == 3 ? "1" : (ver == 2 ? "2" : "2.5"));
|
||||
DPRINTF(E_DBG,L_SCAN," Layer: %d\n",layer);
|
||||
DPRINTF(E_DBG,L_SCAN," Sample Rate: %d\n",samplerate);
|
||||
DPRINTF(E_DBG,L_SCAN," Bit Rate: %d\n",bitrate);
|
||||
|
||||
if(ver == 3) { /* MPEG 1 */
|
||||
if(stereo) {
|
||||
xing_offset=32;
|
||||
} else {
|
||||
xing_offset=17;
|
||||
}
|
||||
} else {
|
||||
if(stereo) {
|
||||
xing_offset=17;
|
||||
} else {
|
||||
xing_offset=9;
|
||||
}
|
||||
}
|
||||
|
||||
/* now check for an XING header */
|
||||
if(strncasecmp((char*)&buffer[index+xing_offset+4],"XING",4) == 0) {
|
||||
DPRINTF(E_DBG,L_SCAN,"Found Xing header\n");
|
||||
xing_flags=*((int*)&buffer[index+xing_offset+4+4]);
|
||||
xing_flags=ntohs(xing_flags);
|
||||
|
||||
DPRINTF(E_DBG,L_SCAN,"Xing Flags: %02X\n",xing_flags);
|
||||
|
||||
if(xing_flags & 0x1) {
|
||||
/* Frames field is valid... */
|
||||
number_of_frames=*((int*)&buffer[index+xing_offset+4+8]);
|
||||
number_of_frames=ntohs(number_of_frames);
|
||||
}
|
||||
}
|
||||
|
||||
/* guesstimate the file length */
|
||||
if(!pmp3->song_length) { /* could have gotten it from the tag */
|
||||
/* DWB: use ms time instead of seconds, use doubles to
|
||||
avoid overflow */
|
||||
if(!number_of_frames) { /* not vbr */
|
||||
pmp3->song_length = (int) ((double) file_size * 8. /
|
||||
(double) bitrate);
|
||||
|
||||
} else {
|
||||
pmp3->song_length = (int) ((double)(number_of_frames*samples_per_frame*1000.)/
|
||||
(double) samplerate);
|
||||
}
|
||||
|
||||
}
|
||||
DPRINTF(E_DBG,L_SCAN," Song Length: %d\n",pmp3->song_length);
|
||||
} else {
|
||||
/* FIXME: should really scan forward to next sync frame */
|
||||
if(scan_decode_mp3_frame(&buffer[index],&fi)) {
|
||||
fclose(infile);
|
||||
DPRINTF(E_DBG,L_SCAN,"Could not find sync frame\n");
|
||||
return 0;
|
||||
}
|
||||
|
||||
pmp3->bitrate=fi.bitrate;
|
||||
pmp3->samplerate=fi.samplerate;
|
||||
|
||||
DPRINTF(E_DBG,L_SCAN," MPEG Version: %0.1g\n",fi.version);
|
||||
DPRINTF(E_DBG,L_SCAN," Layer: %d\n",fi.layer);
|
||||
DPRINTF(E_DBG,L_SCAN," Sample Rate: %d\n",fi.samplerate);
|
||||
DPRINTF(E_DBG,L_SCAN," Bit Rate: %d\n",fi.bitrate);
|
||||
|
||||
/* now check for an XING header */
|
||||
if(strncasecmp((char*)&buffer[index+fi.xing_offset+4],"XING",4) == 0) {
|
||||
DPRINTF(E_DBG,L_SCAN,"Found Xing header\n");
|
||||
xing_flags=*((int*)&buffer[index+fi.xing_offset+4+4]);
|
||||
xing_flags=ntohs(xing_flags);
|
||||
|
||||
DPRINTF(E_DBG,L_SCAN,"Xing Flags: %02X\n",xing_flags);
|
||||
|
||||
if(xing_flags & 0x1) {
|
||||
/* Frames field is valid... */
|
||||
number_of_frames=*((int*)&buffer[index+fi.xing_offset+4+8]);
|
||||
number_of_frames=ntohs(number_of_frames);
|
||||
}
|
||||
}
|
||||
|
||||
/* guesstimate the file length */
|
||||
if(!pmp3->song_length) { /* could have gotten it from the tag */
|
||||
/* DWB: use ms time instead of seconds, use doubles to
|
||||
avoid overflow */
|
||||
if(!number_of_frames) { /* not vbr */
|
||||
pmp3->song_length = (int) ((double) file_size * 8. /
|
||||
(double) fi.bitrate);
|
||||
|
||||
} else {
|
||||
pmp3->song_length = (int) ((double)(number_of_frames*fi.samples_per_frame*1000.)/
|
||||
(double) fi.samplerate);
|
||||
}
|
||||
|
||||
}
|
||||
DPRINTF(E_DBG,L_SCAN," Song Length: %d\n",pmp3->song_length);
|
||||
|
||||
fclose(infile);
|
||||
return 0;
|
||||
|
|
|
|||
Loading…
Reference in New Issue