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au metadata parser: optimize just a little.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@24982 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Yoshihisa Uchida 2010-03-01 10:37:52 +00:00
parent d586fa1e7c
commit f7533cceaa
1 changed files with 26 additions and 24 deletions
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48
apps/metadata/au.c
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@ -30,15 +30,16 @@
#include "metadata_parsers.h"
#include "logf.h"
/* table of bits per sample / 8 */
static const unsigned char bitspersamples[28] = {
0,
8, /* G.711 MULAW */
8, /* 8bit */
16, /* 16bit */
24, /* 24bit */
32, /* 32bit */
32, /* 32bit */
64, /* 64bit */
1, /* G.711 MULAW */
1, /* 8bit */
2, /* 16bit */
3, /* 24bit */
4, /* 32bit */
4, /* 32bit */
8, /* 64bit */
0, /* Fragmented sample data */
0, /* DSP program */
0, /* 8bit fixed point */
@ -58,10 +59,10 @@ static const unsigned char bitspersamples[28] = {
0, /* G.722 */
0, /* G.723 3bit */
0, /* G.723 5bit */
8, /* G.711 ALAW */
1, /* G.711 ALAW */
};
static int get_au_bitspersample(unsigned int encoding)
static inline unsigned char get_au_bitspersample(unsigned int encoding)
{
if (encoding > 27)
return 0;
@ -72,26 +73,30 @@ bool get_au_metadata(int fd, struct mp3entry* id3)
{
/* Use the trackname part of the id3 structure as a temporary buffer */
unsigned char* buf = (unsigned char *)id3->path;
unsigned long totalsamples = 0;
unsigned long channels = 0;
unsigned long bitspersample = 0;
unsigned long numbytes = 0;
int read_bytes;
int offset;
unsigned char bits_ch; /* bitspersample * channels */
id3->vbr = false; /* All Sun audio files are CBR */
id3->filesize = filesize(fd);
id3->length = 0;
if ((lseek(fd, 0, SEEK_SET) < 0) || ((read_bytes = read(fd, buf, 24)) < 0))
return false;
if (read_bytes < 24 || (memcmp(buf, ".snd", 4) != 0))
{
/* no header */
/*
* no header
*
* frequency: 8000 Hz
* bits per sample: 8 bit
* channel: mono
*/
numbytes = id3->filesize;
bitspersample = 8;
id3->frequency = 8000;
channels = 1;
bits_ch = 1;
}
else
{
@ -106,17 +111,14 @@ bool get_au_metadata(int fd, struct mp3entry* id3)
numbytes = get_long_be(buf + 8);
if (numbytes == (uint32_t)0xffffffff)
numbytes = id3->filesize - offset;
/* bitspersample */
bitspersample = get_au_bitspersample(get_long_be(buf + 12));
/* sample rate */
bits_ch = get_au_bitspersample(get_long_be(buf + 12)) * get_long_be(buf + 20);
id3->frequency = get_long_be(buf + 16);
channels = get_long_be(buf + 20);
}
totalsamples = numbytes / ((((bitspersample - 1) / 8) + 1) * channels);
/* Calculate track length (in ms) and estimate the bitrate (in kbit/s) */
id3->length = ((int64_t) totalsamples * 1000) / id3->frequency;
/* Calculate track length [ms] */
if (bits_ch)
id3->length = ((int64_t)numbytes * 1000LL) / (bits_ch * id3->frequency);
return true;
}