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Cleaned up parse_xing, added support for Info magic, and added a parse_extension_headers function for when LAME tag support is added

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git-svn-id: https://svn.musicpd.org/mpd/trunk@4398 09075e82-0dd4-0310-85a5-a0d7c8717e4f
This commit is contained in:
J. Alexander Treuman 2006-07-18 18:18:02 +00:00
parent e7566b9643
commit 6ea0ba392a
1 changed files with 54 additions and 15 deletions
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69
src/inputPlugins/mp3_plugin.c
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@ -402,16 +402,24 @@ static int decodeNextFrame(mp3DecodeData * data) {
return DECODE_OK;
}
/* xing stuff stolen from alsaplayer */
/* xing stuff stolen from alsaplayer, and heavily modified by jat */
#define XI_MAGIC (('X' << 8) | 'i')
#define NG_MAGIC (('n' << 8) | 'g')
#define IN_MAGIC (('I' << 8) | 'n')
#define FO_MAGIC (('f' << 8) | 'o')
enum xing_magic {
XING_MAGIC_XING, /* VBR */
XING_MAGIC_INFO, /* CBR */
};
struct xing {
long flags; /* valid fields (see below) */
unsigned long frames; /* total number of frames */
unsigned long bytes; /* total number of bytes */
unsigned char toc[100]; /* 100-point seek table */
long scale; /* ?? */
long scale; /* VBR quality */
enum xing_magic magic; /* header magic */
};
enum {
@ -421,54 +429,84 @@ enum {
XING_SCALE = 0x00000008L
};
static int parse_xing(struct xing *xing, struct mad_bitptr ptr, unsigned int bitlen)
static int parse_xing(struct xing *xing, struct mad_bitptr *ptr, int bitlen)
{
unsigned long bits;
int oldbitlen;
int bitsleft;
int i;
oldbitlen = bitlen;
if (bitlen < 16) goto fail;
bits = mad_bit_read(&ptr, 16);
bits = mad_bit_read(ptr, 16);
bitlen -= 16;
if (bits == XI_MAGIC) {
if (bitlen < 16) goto fail;
if (mad_bit_read(&ptr, 16) != NG_MAGIC) goto fail;
if (mad_bit_read(ptr, 16) != NG_MAGIC) goto fail;
bitlen -= 16;
xing->magic = XING_MAGIC_XING;
} else if (bits == IN_MAGIC) {
if (bitlen < 16) goto fail;
if (mad_bit_read(ptr, 16) != FO_MAGIC) goto fail;
bitlen -= 16;
xing->magic = XING_MAGIC_INFO;
}
else if (bits != NG_MAGIC) goto fail;
else if (bits == NG_MAGIC) xing->magic = XING_MAGIC_XING;
else if (bits == FO_MAGIC) xing->magic = XING_MAGIC_INFO;
else goto fail;
if (bitlen < 32) goto fail;
xing->flags = mad_bit_read(&ptr, 32);
xing->flags = mad_bit_read(ptr, 32);
bitlen -= 32;
if (xing->flags & XING_FRAMES) {
if (bitlen < 32) goto fail;
xing->frames = mad_bit_read(&ptr, 32);
xing->frames = mad_bit_read(ptr, 32);
bitlen -= 32;
}
if (xing->flags & XING_BYTES) {
if (bitlen < 32) goto fail;
xing->bytes = mad_bit_read(&ptr, 32);
xing->bytes = mad_bit_read(ptr, 32);
bitlen -= 32;
}
if (xing->flags & XING_TOC) {
int i;
if (bitlen < 800) goto fail;
for (i = 0; i < 100; ++i) xing->toc[i] = mad_bit_read(&ptr, 8);
for (i = 0; i < 100; ++i) xing->toc[i] = mad_bit_read(ptr, 8);
bitlen -= 800;
}
if (xing->flags & XING_SCALE) {
if (bitlen < 32) goto fail;
xing->scale = mad_bit_read(&ptr, 32);
xing->scale = mad_bit_read(ptr, 32);
bitlen -= 32;
}
return 1;
/* Make sure we consume no less than 120 bytes (960 bits) in hopes that
* the LAME tag is found there, and not right after the Xing header */
bitsleft = 960-(oldbitlen-bitlen);
if (bitsleft < 0) goto fail;
else if (bitsleft > 0) {
mad_bit_read(ptr, bitsleft);
bitlen -= bitsleft;
}
return bitlen;
fail:
xing->flags = 0;
return 0;
return -1;
}
static int parse_extension_headers(struct xing *xing, struct mad_bitptr ptr,
int bitlen)
{
bitlen = parse_xing(xing, &ptr, bitlen);
if (bitlen < 0) return 0;
return 1;
}
static int decodeFirstFrame(mp3DecodeData * data, DecoderControl * dc,
@ -493,7 +531,8 @@ static int decodeFirstFrame(mp3DecodeData * data, DecoderControl * dc,
if(!skip && ret==DECODE_OK) break;
}
if(parse_xing(&xing,data->stream.anc_ptr,data->stream.anc_bitlen)) {
if(parse_extension_headers(&xing, data->stream.anc_ptr,
(int)data->stream.anc_bitlen)) {
if(xing.flags & XING_FRAMES) {
mad_timer_t duration = data->frame.header.duration;
mad_timer_multiply(&duration,xing.frames);