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skip junk in mp3_helix, refactor find_sync_word

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git-svn-id: file:///home/notaz/opt/svn/PicoDrive@889 be3aeb3a-fb24-0410-a615-afba39da0efa
This commit is contained in:
notaz 2010-09-08 20:52:13 +00:00
parent cf82669f50
commit 7c18e34a74
13 changed files with 86 additions and 82 deletions
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29
platform/common/mp3.c Normal file
View file

@ -0,0 +1,29 @@
#include "mp3.h"
int mp3_find_sync_word(const unsigned char *buf, int size)
{
const unsigned char *p, *pe;
/* find byte-aligned syncword - need 12 (MPEG 1,2) or 11 (MPEG 2.5) matching bits */
for (p = buf, pe = buf + size - 3; p <= pe; p++)
{
int pn;
if (p[0] != 0xff)
continue;
pn = p[1];
if ((pn & 0xf8) != 0xf8 || // currently must be MPEG1
(pn & 6) == 0) { // invalid layer
p++; continue;
}
pn = p[2];
if ((pn & 0xf0) < 0x20 || (pn & 0xf0) == 0xf0 || // bitrates
(pn & 0x0c) != 0) { // not 44kHz
continue;
}
return p - buf;
}
return -1;
}

4
platform/common/mp3.h
View file

@ -1,6 +1,8 @@
int mp3_find_sync_word(const unsigned char *buf, int size);
#ifdef __GP2X__
void mp3_update_local(int *buffer, int length, int stereo);
void mp3_start_play_local(FILE *f, int pos);
void mp3_start_play_local(void *f, int pos);
#endif

70
platform/common/mp3_helix.c
View file

@ -23,39 +23,13 @@ static unsigned char mp3_input_buffer[2*1024];
#define mp3_start_play mp3_start_play_local
#endif
static int find_sync_word(unsigned char *buf, int nBytes)
{
unsigned char *p, *pe;
/* find byte-aligned syncword - need 12 (MPEG 1,2) or 11 (MPEG 2.5) matching bits */
for (p = buf, pe = buf + nBytes - 4; p < pe; p++)
{
int pn;
if (p[0] != 0xff) continue;
pn = p[1];
if ((pn & 0xf8) != 0xf8 || // currently must be MPEG1
(pn & 6) == 0) { // invalid layer
p++; continue;
}
pn = p[2];
if ((pn & 0xf0) < 0x20 || (pn & 0xf0) == 0xf0 || // bitrates
(pn & 0x0c) != 0) { // not 44kHz
continue;
}
return p - buf;
}
return -1;
}
static int try_get_header(unsigned char *buff, MP3FrameInfo *fi)
{
int ret, offs1, offs = 0;
while (1)
{
offs1 = find_sync_word(buff + offs, 2048 - offs);
offs1 = mp3_find_sync_word(buff + offs, 2048 - offs);
if (offs1 < 0) return -2;
offs += offs1;
if (2048 - offs < 4) return -3;
@ -70,21 +44,24 @@ static int try_get_header(unsigned char *buff, MP3FrameInfo *fi)
return ret;
}
int mp3_get_bitrate(FILE *f, int len)
int mp3_get_bitrate(void *f_, int len)
{
unsigned char buff[2048];
MP3FrameInfo fi;
FILE *f = f_;
int ret;
memset(buff, 0, 2048);
memset(buff, 0, sizeof(buff));
if (mp3dec) MP3FreeDecoder(mp3dec);
if (mp3dec)
MP3FreeDecoder(mp3dec);
mp3dec = MP3InitDecoder();
fseek(f, 0, SEEK_SET);
ret = fread(buff, 1, 2048, f);
ret = fread(buff, 1, sizeof(buff), f);
fseek(f, 0, SEEK_SET);
if (ret <= 0) return -1;
if (ret <= 0)
return -1;
ret = try_get_header(buff, &fi);
if (ret != 0 || fi.bitrate == 0) {
@ -94,7 +71,8 @@ int mp3_get_bitrate(FILE *f, int len)
fseek(f, 0, SEEK_SET);
ret = try_get_header(buff, &fi);
}
if (ret != 0) return ret;
if (ret != 0)
return ret;
// printf("bitrate: %i\n", fi.bitrate / 1000);
@ -117,7 +95,7 @@ static int mp3_decode(void)
fseek(mp3_current_file, mp3_file_pos, SEEK_SET);
bytesLeft = fread(mp3_input_buffer, 1, sizeof(mp3_input_buffer), mp3_current_file);
offset = find_sync_word(mp3_input_buffer, bytesLeft);
offset = mp3_find_sync_word(mp3_input_buffer, bytesLeft);
if (offset < 0) {
lprintf("find_sync_word (%i/%i) err %i\n", mp3_file_pos, mp3_file_len, offset);
mp3_file_pos = mp3_file_len;
@ -159,8 +137,10 @@ static int mp3_decode(void)
return 0;
}
void mp3_start_play(FILE *f, int pos)
void mp3_start_play(void *f_, int pos)
{
FILE *f = f_;
mp3_file_len = mp3_file_pos = 0;
mp3_current_file = NULL;
mp3_buffer_offs = 0;
@ -177,11 +157,27 @@ void mp3_start_play(FILE *f, int pos)
fseek(f, 0, SEEK_END);
mp3_file_len = ftell(f);
// search for first sync word, skipping stuff like ID3 tags
while (mp3_file_pos < 128*1024) {
int offs, bytes;
fseek(f, mp3_file_pos, SEEK_SET);
bytes = fread(mp3_input_buffer, 1, sizeof(mp3_input_buffer), f);
if (bytes < 4)
break;
offs = mp3_find_sync_word(mp3_input_buffer, bytes);
if (offs >= 0) {
mp3_file_pos += offs;
break;
}
mp3_file_pos += bytes - 2;
}
// seek..
if (pos) {
unsigned long long pos64 = mp3_file_len;
unsigned long long pos64 = mp3_file_len - mp3_file_pos;
pos64 *= pos;
mp3_file_pos = pos64 >> 10;
mp3_file_pos += pos64 >> 10;
}
mp3_decode();