src/gpacmp4/gpac_ogg.c

/********************************************************************
*                                                                  *
* THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE.   *
* USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
* GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
* IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
*                                                                  *
* THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2002             *
* by the Xiph.Org Foundation http://www.xiph.org/                  *
*                                                                  *
********************************************************************

function: code raw [Vorbis] packets into framed OggSquish stream and
decode Ogg streams back into raw packets

note: The CRC code is directly derived from public domain code by
Ross Williams (ross@guest.adelaide.edu.au).  See docs/framing.html
for details.

********************************************************************/


#include <gpac/internal/ogg.h>

#ifndef GPAC_DISABLE_OGG

#define BUFFER_INCREMENT 256

static u32 mask[] =
{ 0x00000000,0x00000001,0x00000003,0x00000007,0x0000000f,
0x0000001f,0x0000003f,0x0000007f,0x000000ff,0x000001ff,
0x000003ff,0x000007ff,0x00000fff,0x00001fff,0x00003fff,
0x00007fff,0x0000ffff,0x0001ffff,0x0003ffff,0x0007ffff,
0x000fffff,0x001fffff,0x003fffff,0x007fffff,0x00ffffff,
0x01ffffff,0x03ffffff,0x07ffffff,0x0fffffff,0x1fffffff,
0x3fffffff,0x7fffffff,0xffffffff
};

static u32 mask8B[] =
{ 0x00,0x80,0xc0,0xe0,0xf0,0xf8,0xfc,0xfe,0xff };

void oggpack_writeinit(oggpack_buffer *b) {
	memset(b, 0, sizeof(*b));
	b->ptr = b->buffer = (unsigned char *)gf_malloc(BUFFER_INCREMENT);
	b->buffer[0] = '\0';
	b->storage = BUFFER_INCREMENT;
}

void oggpackB_writeinit(oggpack_buffer *b) {
	oggpack_writeinit(b);
}

void oggpack_writetrunc(oggpack_buffer *b, s32 bits) {
	s32 bytes = bits >> 3;
	bits -= bytes * 8;
	b->ptr = b->buffer + bytes;
	b->endbit = bits;
	b->endbyte = bytes;
	*b->ptr &= mask[bits];
}

void oggpackB_writetrunc(oggpack_buffer *b, s32 bits) {
	s32 bytes = bits >> 3;
	bits -= bytes * 8;
	b->ptr = b->buffer + bytes;
	b->endbit = bits;
	b->endbyte = bytes;
	*b->ptr &= mask8B[bits];
}

/* Takes only up to 32 bits. */
void oggpack_write(oggpack_buffer *b, u32 value, s32 bits) {
	if (b->endbyte + 4 >= b->storage) {
		b->buffer = (unsigned char *)gf_realloc(b->buffer, b->storage + BUFFER_INCREMENT);
		b->storage += BUFFER_INCREMENT;
		b->ptr = b->buffer + b->endbyte;
	}

	value &= mask[bits];
	bits += b->endbit;

	b->ptr[0] |= value << b->endbit;

	if (bits >= 8) {
		b->ptr[1] = value >> (8 - b->endbit);
		if (bits >= 16) {
			b->ptr[2] = value >> (16 - b->endbit);
			if (bits >= 24) {
				b->ptr[3] = value >> (24 - b->endbit);
				if (bits >= 32) {
					if (b->endbit)
						b->ptr[4] = value >> (32 - b->endbit);
					else
						b->ptr[4] = 0;
				}
			}
		}
	}

	b->endbyte += bits / 8;
	b->ptr += bits / 8;
	b->endbit = bits & 7;
}

/* Takes only up to 32 bits. */
void oggpackB_write(oggpack_buffer *b, u32 value, s32 bits) {
	if (b->endbyte + 4 >= b->storage) {
		b->buffer = (unsigned char *)gf_realloc(b->buffer, b->storage + BUFFER_INCREMENT);
		b->storage += BUFFER_INCREMENT;
		b->ptr = b->buffer + b->endbyte;
	}

	value = (value&mask[bits]) << (32 - bits);
	bits += b->endbit;

	b->ptr[0] |= value >> (24 + b->endbit);

	if (bits >= 8) {
		b->ptr[1] = value >> (16 + b->endbit);
		if (bits >= 16) {
			b->ptr[2] = value >> (8 + b->endbit);
			if (bits >= 24) {
				b->ptr[3] = value >> (b->endbit);
				if (bits >= 32) {
					if (b->endbit)
						b->ptr[4] = value << (8 - b->endbit);
					else
						b->ptr[4] = 0;
				}
			}
		}
	}

	b->endbyte += bits / 8;
	b->ptr += bits / 8;
	b->endbit = bits & 7;
}

void oggpack_writealign(oggpack_buffer *b) {
	s32 bits = 8 - b->endbit;
	if (bits<8)
		oggpack_write(b, 0, bits);
}

void oggpackB_writealign(oggpack_buffer *b) {
	s32 bits = 8 - b->endbit;
	if (bits<8)
		oggpackB_write(b, 0, bits);
}

static void oggpack_writecopy_helper(oggpack_buffer *b,
	void *source,
	s32 bits,
	void(*w)(oggpack_buffer *,
		u32,
		s32),
	s32 msb) {
	unsigned char *ptr = (unsigned char *)source;

	s32 bytes = bits / 8;
	bits -= bytes * 8;

	if (b->endbit) {
		s32 i;
		/* unaligned copy.  Do it the hard way. */
		for (i = 0; i<bytes; i++)
			w(b, (u32)(ptr[i]), 8);
	}
	else {
		/* aligned block copy */
		if (b->endbyte + bytes + 1 >= b->storage) {
			b->storage = b->endbyte + bytes + BUFFER_INCREMENT;
			b->buffer = (unsigned char *)gf_realloc(b->buffer, b->storage);
			b->ptr = b->buffer + b->endbyte;
		}

		memmove(b->ptr, source, bytes);
		b->ptr += bytes;
		b->buffer += bytes;
		*b->ptr = 0;

	}
	if (bits) {
		if (msb)
			w(b, (u32)(ptr[bytes] >> (8 - bits)), bits);
		else
			w(b, (u32)(ptr[bytes]), bits);
	}
}

void oggpack_writecopy(oggpack_buffer *b, void *source, s32 bits) {
	oggpack_writecopy_helper(b, source, bits, oggpack_write, 0);
}

void oggpackB_writecopy(oggpack_buffer *b, void *source, s32 bits) {
	oggpack_writecopy_helper(b, source, bits, oggpackB_write, 1);
}

void oggpack_reset(oggpack_buffer *b) {
	b->ptr = b->buffer;
	b->buffer[0] = 0;
	b->endbit = b->endbyte = 0;
}

void oggpackB_reset(oggpack_buffer *b) {
	oggpack_reset(b);
}

void oggpack_writeclear(oggpack_buffer *b) {
	gf_free(b->buffer);
	memset(b, 0, sizeof(*b));
}

void oggpackB_writeclear(oggpack_buffer *b) {
	oggpack_writeclear(b);
}

void oggpack_readinit(oggpack_buffer *b, unsigned char *buf, s32 bytes) {
	memset(b, 0, sizeof(*b));
	b->buffer = b->ptr = buf;
	b->storage = bytes;
}

void oggpackB_readinit(oggpack_buffer *b, unsigned char *buf, s32 bytes) {
	oggpack_readinit(b, buf, bytes);
}

/* Read in bits without advancing the bitptr; bits <= 32 */
s32 oggpack_look(oggpack_buffer *b, s32 bits) {
	u32 ret;
	u32 m = mask[bits];

	bits += b->endbit;

	if (b->endbyte + 4 >= b->storage) {
		/* not the main path */
		if (b->endbyte * 8 + bits>b->storage * 8)return(-1);
	}

	ret = b->ptr[0] >> b->endbit;
	if (bits>8) {
		ret |= b->ptr[1] << (8 - b->endbit);
		if (bits>16) {
			ret |= b->ptr[2] << (16 - b->endbit);
			if (bits>24) {
				ret |= b->ptr[3] << (24 - b->endbit);
				if (bits>32 && b->endbit)
					ret |= b->ptr[4] << (32 - b->endbit);
			}
		}
	}
	return(m&ret);
}

/* Read in bits without advancing the bitptr; bits <= 32 */
s32 oggpackB_look(oggpack_buffer *b, s32 bits) {
	u32 ret;
	s32 m = 32 - bits;

	bits += b->endbit;

	if (b->endbyte + 4 >= b->storage) {
		/* not the main path */
		if (b->endbyte * 8 + bits>b->storage * 8)return(-1);
	}

	ret = b->ptr[0] << (24 + b->endbit);
	if (bits>8) {
		ret |= b->ptr[1] << (16 + b->endbit);
		if (bits>16) {
			ret |= b->ptr[2] << (8 + b->endbit);
			if (bits>24) {
				ret |= b->ptr[3] << (b->endbit);
				if (bits>32 && b->endbit)
					ret |= b->ptr[4] >> (8 - b->endbit);
			}
		}
	}
	return (ret >> (m >> 1)) >> ((m + 1) >> 1);
}

s32 oggpack_look1(oggpack_buffer *b) {
	if (b->endbyte >= b->storage)return(-1);
	return((b->ptr[0] >> b->endbit) & 1);
}

s32 oggpackB_look1(oggpack_buffer *b) {
	if (b->endbyte >= b->storage)return(-1);
	return((b->ptr[0] >> (7 - b->endbit)) & 1);
}

void oggpack_adv(oggpack_buffer *b, s32 bits) {
	bits += b->endbit;
	b->ptr += bits / 8;
	b->endbyte += bits / 8;
	b->endbit = bits & 7;
}

void oggpackB_adv(oggpack_buffer *b, s32 bits) {
	oggpack_adv(b, bits);
}

void oggpack_adv1(oggpack_buffer *b) {
	if (++(b->endbit)>7) {
		b->endbit = 0;
		b->ptr++;
		b->endbyte++;
	}
}

void oggpackB_adv1(oggpack_buffer *b) {
	oggpack_adv1(b);
}

/* bits <= 32 */
s32 oggpack_read(oggpack_buffer *b, s32 bits) {
	u32 ret;
	u32 m = mask[bits];

	bits += b->endbit;

	if (b->endbyte + 4 >= b->storage) {
		/* not the main path */
		ret = (u32)(-1);
		if (b->endbyte * 8 + bits>b->storage * 8)goto overflow;
	}

	ret = b->ptr[0] >> b->endbit;
	if (bits>8) {
		ret |= b->ptr[1] << (8 - b->endbit);
		if (bits>16) {
			ret |= b->ptr[2] << (16 - b->endbit);
			if (bits>24) {
				ret |= b->ptr[3] << (24 - b->endbit);
				if (bits>32 && b->endbit) {
					ret |= b->ptr[4] << (32 - b->endbit);
				}
			}
		}
	}
	ret &= m;

overflow:

	b->ptr += bits / 8;
	b->endbyte += bits / 8;
	b->endbit = bits & 7;
	return(ret);
}

/* bits <= 32 */
s32 oggpackB_read(oggpack_buffer *b, s32 bits) {
	u32 ret;
	s32 m = 32 - bits;

	bits += b->endbit;

	if (b->endbyte + 4 >= b->storage) {
		/* not the main path */
		ret = (u32)(-1);
		if (b->endbyte * 8 + bits>b->storage * 8)goto overflow;
	}

	ret = b->ptr[0] << (24 + b->endbit);
	if (bits>8) {
		ret |= b->ptr[1] << (16 + b->endbit);
		if (bits>16) {
			ret |= b->ptr[2] << (8 + b->endbit);
			if (bits>24) {
				ret |= b->ptr[3] << (b->endbit);
				if (bits>32 && b->endbit)
					ret |= b->ptr[4] >> (8 - b->endbit);
			}
		}
	}
	ret = (ret >> (m >> 1)) >> ((m + 1) >> 1);

overflow:

	b->ptr += bits / 8;
	b->endbyte += bits / 8;
	b->endbit = bits & 7;
	return(ret);
}

s32 oggpack_read1(oggpack_buffer *b) {
	u32 ret;

	if (b->endbyte >= b->storage) {
		/* not the main path */
		ret = (u32)(-1);
		goto overflow;
	}

	ret = (b->ptr[0] >> b->endbit) & 1;

overflow:

	b->endbit++;
	if (b->endbit>7) {
		b->endbit = 0;
		b->ptr++;
		b->endbyte++;
	}
	return(ret);
}

s32 oggpackB_read1(oggpack_buffer *b) {
	u32 ret;

	if (b->endbyte >= b->storage) {
		/* not the main path */
		ret = (u32)(-1);
		goto overflow;
	}

	ret = (b->ptr[0] >> (7 - b->endbit)) & 1;

overflow:

	b->endbit++;
	if (b->endbit>7) {
		b->endbit = 0;
		b->ptr++;
		b->endbyte++;
	}
	return(ret);
}

s32 oggpack_bytes(oggpack_buffer *b) {
	return(b->endbyte + (b->endbit + 7) / 8);
}

s32 oggpack_bits(oggpack_buffer *b) {
	return(b->endbyte * 8 + b->endbit);
}

s32 oggpackB_bytes(oggpack_buffer *b) {
	return oggpack_bytes(b);
}

s32 oggpackB_bits(oggpack_buffer *b) {
	return oggpack_bits(b);
}

unsigned char *oggpack_get_buffer(oggpack_buffer *b) {
	return(b->buffer);
}

unsigned char *oggpackB_get_buffer(oggpack_buffer *b) {
	return oggpack_get_buffer(b);
}


#undef BUFFER_INCREMENT

/* A complete description of Ogg framing exists in docs/framing.html */

s32 ogg_page_version(ogg_page *og) {
	return((s32)(og->header[4]));
}

s32 ogg_page_continued(ogg_page *og) {
	return((s32)(og->header[5] & 0x01));
}

s32 ogg_page_bos(ogg_page *og) {
	return((s32)(og->header[5] & 0x02));
}

s32 ogg_page_eos(ogg_page *og) {
	return((s32)(og->header[5] & 0x04));
}

s64 ogg_page_granulepos(ogg_page *og) {
	unsigned char *page = og->header;
	s64 granulepos = page[13] & (0xff);
	granulepos = (granulepos << 8) | (page[12] & 0xff);
	granulepos = (granulepos << 8) | (page[11] & 0xff);
	granulepos = (granulepos << 8) | (page[10] & 0xff);
	granulepos = (granulepos << 8) | (page[9] & 0xff);
	granulepos = (granulepos << 8) | (page[8] & 0xff);
	granulepos = (granulepos << 8) | (page[7] & 0xff);
	granulepos = (granulepos << 8) | (page[6] & 0xff);
	return(granulepos);
}

s32 ogg_page_serialno(ogg_page *og) {
	return(og->header[14] |
		(og->header[15] << 8) |
		(og->header[16] << 16) |
		(og->header[17] << 24));
}

s32 ogg_page_pageno(ogg_page *og) {
	return(og->header[18] |
		(og->header[19] << 8) |
		(og->header[20] << 16) |
		(og->header[21] << 24));
}


/* returns the number of packets that are completed on this page (if
the leading packet is begun on a previous page, but ends on this
page, it's counted */

/* NOTE:
If a page consists of a packet begun on a previous page, and a new
packet begun (but not completed) on this page, the return will be:
ogg_page_packets(page)   ==1,
ogg_page_continued(page) !=0

If a page happens to be a single packet that was begun on a
previous page, and spans to the next page (in the case of a three or
more page packet), the return will be:
ogg_page_packets(page)   ==0,
ogg_page_continued(page) !=0
*/

s32 ogg_page_packets(ogg_page *og) {
	s32 i, n = og->header[26], count = 0;
	for (i = 0; i<n; i++)
		if (og->header[27 + i]<255)count++;
	return(count);
}


#if 0
/* helper to initialize lookup for direct-table CRC (illustrative; we
use the static init below) */

static u32 _ogg_crc_entry(u32 index) {
	s32           i;
	u32 r;

	r = index << 24;
	for (i = 0; i<8; i++)
		if (r & 0x80000000UL)
			r = (r << 1) ^ 0x04c11db7; /* The same as the ethernet generator
									   polynomial, although we use an
									   unreflected alg and an init/final
									   of 0, not 0xffffffff */
		else
			r <<= 1;
	return (r & 0xffffffffUL);
}
#endif

static u32 crc_lookup[256] = {
	0x00000000,0x04c11db7,0x09823b6e,0x0d4326d9,
	0x130476dc,0x17c56b6b,0x1a864db2,0x1e475005,
	0x2608edb8,0x22c9f00f,0x2f8ad6d6,0x2b4bcb61,
	0x350c9b64,0x31cd86d3,0x3c8ea00a,0x384fbdbd,
	0x4c11db70,0x48d0c6c7,0x4593e01e,0x4152fda9,
	0x5f15adac,0x5bd4b01b,0x569796c2,0x52568b75,
	0x6a1936c8,0x6ed82b7f,0x639b0da6,0x675a1011,
	0x791d4014,0x7ddc5da3,0x709f7b7a,0x745e66cd,
	0x9823b6e0,0x9ce2ab57,0x91a18d8e,0x95609039,
	0x8b27c03c,0x8fe6dd8b,0x82a5fb52,0x8664e6e5,
	0xbe2b5b58,0xbaea46ef,0xb7a96036,0xb3687d81,
	0xad2f2d84,0xa9ee3033,0xa4ad16ea,0xa06c0b5d,
	0xd4326d90,0xd0f37027,0xddb056fe,0xd9714b49,
	0xc7361b4c,0xc3f706fb,0xceb42022,0xca753d95,
	0xf23a8028,0xf6fb9d9f,0xfbb8bb46,0xff79a6f1,
	0xe13ef6f4,0xe5ffeb43,0xe8bccd9a,0xec7dd02d,
	0x34867077,0x30476dc0,0x3d044b19,0x39c556ae,
	0x278206ab,0x23431b1c,0x2e003dc5,0x2ac12072,
	0x128e9dcf,0x164f8078,0x1b0ca6a1,0x1fcdbb16,
	0x018aeb13,0x054bf6a4,0x0808d07d,0x0cc9cdca,
	0x7897ab07,0x7c56b6b0,0x71159069,0x75d48dde,
	0x6b93dddb,0x6f52c06c,0x6211e6b5,0x66d0fb02,
	0x5e9f46bf,0x5a5e5b08,0x571d7dd1,0x53dc6066,
	0x4d9b3063,0x495a2dd4,0x44190b0d,0x40d816ba,
	0xaca5c697,0xa864db20,0xa527fdf9,0xa1e6e04e,
	0xbfa1b04b,0xbb60adfc,0xb6238b25,0xb2e29692,
	0x8aad2b2f,0x8e6c3698,0x832f1041,0x87ee0df6,
	0x99a95df3,0x9d684044,0x902b669d,0x94ea7b2a,
	0xe0b41de7,0xe4750050,0xe9362689,0xedf73b3e,
	0xf3b06b3b,0xf771768c,0xfa325055,0xfef34de2,
	0xc6bcf05f,0xc27dede8,0xcf3ecb31,0xcbffd686,
	0xd5b88683,0xd1799b34,0xdc3abded,0xd8fba05a,
	0x690ce0ee,0x6dcdfd59,0x608edb80,0x644fc637,
	0x7a089632,0x7ec98b85,0x738aad5c,0x774bb0eb,
	0x4f040d56,0x4bc510e1,0x46863638,0x42472b8f,
	0x5c007b8a,0x58c1663d,0x558240e4,0x51435d53,
	0x251d3b9e,0x21dc2629,0x2c9f00f0,0x285e1d47,
	0x36194d42,0x32d850f5,0x3f9b762c,0x3b5a6b9b,
	0x0315d626,0x07d4cb91,0x0a97ed48,0x0e56f0ff,
	0x1011a0fa,0x14d0bd4d,0x19939b94,0x1d528623,
	0xf12f560e,0xf5ee4bb9,0xf8ad6d60,0xfc6c70d7,
	0xe22b20d2,0xe6ea3d65,0xeba91bbc,0xef68060b,
	0xd727bbb6,0xd3e6a601,0xdea580d8,0xda649d6f,
	0xc423cd6a,0xc0e2d0dd,0xcda1f604,0xc960ebb3,
	0xbd3e8d7e,0xb9ff90c9,0xb4bcb610,0xb07daba7,
	0xae3afba2,0xaafbe615,0xa7b8c0cc,0xa379dd7b,
	0x9b3660c6,0x9ff77d71,0x92b45ba8,0x9675461f,
	0x8832161a,0x8cf30bad,0x81b02d74,0x857130c3,
	0x5d8a9099,0x594b8d2e,0x5408abf7,0x50c9b640,
	0x4e8ee645,0x4a4ffbf2,0x470cdd2b,0x43cdc09c,
	0x7b827d21,0x7f436096,0x7200464f,0x76c15bf8,
	0x68860bfd,0x6c47164a,0x61043093,0x65c52d24,
	0x119b4be9,0x155a565e,0x18197087,0x1cd86d30,
	0x029f3d35,0x065e2082,0x0b1d065b,0x0fdc1bec,
	0x3793a651,0x3352bbe6,0x3e119d3f,0x3ad08088,
	0x2497d08d,0x2056cd3a,0x2d15ebe3,0x29d4f654,
	0xc5a92679,0xc1683bce,0xcc2b1d17,0xc8ea00a0,
	0xd6ad50a5,0xd26c4d12,0xdf2f6bcb,0xdbee767c,
	0xe3a1cbc1,0xe760d676,0xea23f0af,0xeee2ed18,
	0xf0a5bd1d,0xf464a0aa,0xf9278673,0xfde69bc4,
	0x89b8fd09,0x8d79e0be,0x803ac667,0x84fbdbd0,
	0x9abc8bd5,0x9e7d9662,0x933eb0bb,0x97ffad0c,
	0xafb010b1,0xab710d06,0xa6322bdf,0xa2f33668,
	0xbcb4666d,0xb8757bda,0xb5365d03,0xb1f740b4
};

/* init the encode/decode logical stream state */

s32 ogg_stream_init(ogg_stream_state *os, s32 serialno) {
	if (os) {
		memset(os, 0, sizeof(*os));
		os->body_storage = 16 * 1024;
		os->body_data = (unsigned char *)gf_malloc(os->body_storage * sizeof(*os->body_data));

		os->lacing_storage = 1024;
		os->lacing_vals = (s32 *)gf_malloc(os->lacing_storage * sizeof(*os->lacing_vals));
		os->granule_vals = (s64*)gf_malloc(os->lacing_storage * sizeof(*os->granule_vals));

		os->serialno = serialno;

		return(0);
	}
	return(-1);
}

/* _clear does not free os, only the non-flat storage within */
s32 ogg_stream_clear(ogg_stream_state *os) {
	if (os) {
		if (os->body_data)gf_free(os->body_data);
		if (os->lacing_vals)gf_free(os->lacing_vals);
		if (os->granule_vals)gf_free(os->granule_vals);

		memset(os, 0, sizeof(*os));
	}
	return(0);
}

s32 ogg_stream_destroy(ogg_stream_state *os) {
	if (os) {
		ogg_stream_clear(os);
		gf_free(os);
	}
	return(0);
}

/* Helpers for ogg_stream_encode; this keeps the structure and
what's happening fairly clear */

static void _os_body_expand(ogg_stream_state *os, s32 needed) {
	if (os->body_storage <= os->body_fill + needed) {
		os->body_storage += (needed + 1024);
		os->body_data = (unsigned char *)gf_realloc(os->body_data, os->body_storage * sizeof(*os->body_data));
	}
}

static void _os_lacing_expand(ogg_stream_state *os, s32 needed) {
	if (os->lacing_storage <= os->lacing_fill + needed) {
		os->lacing_storage += (needed + 32);
		os->lacing_vals = (s32*)gf_realloc(os->lacing_vals, os->lacing_storage * sizeof(*os->lacing_vals));
		os->granule_vals = (s64*)gf_realloc(os->granule_vals, os->lacing_storage * sizeof(*os->granule_vals));
	}
}

/* checksum the page */
/* Direct table CRC; note that this will be faster in the future if we
perform the checksum silmultaneously with other copies */

void ogg_page_checksum_set(ogg_page *og) {
	if (og) {
		u32 crc_reg = 0;
		s32 i;

		/* safety; needed for API behavior, but not framing code */
		og->header[22] = 0;
		og->header[23] = 0;
		og->header[24] = 0;
		og->header[25] = 0;

		for (i = 0; i<og->header_len; i++)
			crc_reg = (crc_reg << 8) ^ crc_lookup[((crc_reg >> 24) & 0xff) ^ og->header[i]];
		for (i = 0; i<og->body_len; i++)
			crc_reg = (crc_reg << 8) ^ crc_lookup[((crc_reg >> 24) & 0xff) ^ og->body[i]];

		og->header[22] = crc_reg & 0xff;
		og->header[23] = (crc_reg >> 8) & 0xff;
		og->header[24] = (crc_reg >> 16) & 0xff;
		og->header[25] = (crc_reg >> 24) & 0xff;
	}
}

/* submit data to the internal buffer of the framing engine */
s32 ogg_stream_packetin(ogg_stream_state *os, ogg_packet *op) {
	s32 lacing_vals = op->bytes / 255 + 1, i;

	if (os->body_returned) {
		/* advance packet data according to the body_returned pointer. We
		had to keep it around to return a pointer into the buffer last
		call */

		os->body_fill -= os->body_returned;
		if (os->body_fill)
			memmove(os->body_data, os->body_data + os->body_returned,
				os->body_fill);
		os->body_returned = 0;
	}

	/* make sure we have the buffer storage */
	_os_body_expand(os, op->bytes);
	_os_lacing_expand(os, lacing_vals);

	/* Copy in the submitted packet.  Yes, the copy is a waste; this is
	the liability of overly clean abstraction for the time being.  It
	will actually be fairly easy to eliminate the extra copy in the
	future */

	memcpy(os->body_data + os->body_fill, op->packet, op->bytes);
	os->body_fill += op->bytes;

	/* Store lacing vals for this packet */
	for (i = 0; i<lacing_vals - 1; i++) {
		os->lacing_vals[os->lacing_fill + i] = 255;
		os->granule_vals[os->lacing_fill + i] = os->granulepos;
	}
	os->lacing_vals[os->lacing_fill + i] = (op->bytes) % 255;
	os->granulepos = os->granule_vals[os->lacing_fill + i] = op->granulepos;

	/* flag the first segment as the beginning of the packet */
	os->lacing_vals[os->lacing_fill] |= 0x100;

	os->lacing_fill += lacing_vals;

	/* for the sake of completeness */
	os->packetno++;

	if (op->e_o_s)os->e_o_s = 1;

	return(0);
}

/* This will flush remaining packets into a page (returning nonzero),
even if there is not enough data to trigger a flush normally
(undersized page). If there are no packets or partial packets to
flush, ogg_stream_flush returns 0.  Note that ogg_stream_flush will
try to flush a normal sized page like ogg_stream_pageout; a call to
ogg_stream_flush does not guarantee that all packets have flushed.
Only a return value of 0 from ogg_stream_flush indicates all packet
data is flushed into pages.

since ogg_stream_flush will flush the last page in a stream even if
it's undersized, you almost certainly want to use ogg_stream_pageout
(and *not* ogg_stream_flush) unless you specifically need to flush
an page regardless of size in the middle of a stream. */

s32 ogg_stream_flush(ogg_stream_state *os, ogg_page *og) {
	s32 i;
	s32 vals = 0;
	s32 maxvals = (os->lacing_fill>255 ? 255 : os->lacing_fill);
	s32 bytes = 0;
	s32 acc = 0;
	s64 granule_pos = os->granule_vals[0];

	if (maxvals == 0)return(0);

	/* construct a page */
	/* decide how many segments to include */

	/* If this is the initial header case, the first page must only include
	the initial header packet */
	if (os->b_o_s == 0) { /* 'initial header page' case */
		granule_pos = 0;
		for (vals = 0; vals<maxvals; vals++) {
			if ((os->lacing_vals[vals] & 0x0ff)<255) {
				vals++;
				break;
			}
		}
	}
	else {
		for (vals = 0; vals<maxvals; vals++) {
			if (acc>4096)break;
			acc += os->lacing_vals[vals] & 0x0ff;
			granule_pos = os->granule_vals[vals];
		}
	}

	/* construct the header in temp storage */
	memcpy(os->header, "OggS", 4);

	/* stream structure version */
	os->header[4] = 0x00;

	/* continued packet flag? */
	os->header[5] = 0x00;
	if ((os->lacing_vals[0] & 0x100) == 0)os->header[5] |= 0x01;
	/* first page flag? */
	if (os->b_o_s == 0)os->header[5] |= 0x02;
	/* last page flag? */
	if (os->e_o_s && os->lacing_fill == vals)os->header[5] |= 0x04;
	os->b_o_s = 1;

	/* 64 bits of PCM position */
	for (i = 6; i<14; i++) {
		os->header[i] = (u8)(granule_pos & 0xff);
		granule_pos >>= 8;
	}

	/* 32 bits of stream serial number */
	{
		s32 serialno = os->serialno;
		for (i = 14; i<18; i++) {
			os->header[i] = (serialno & 0xff);
			serialno >>= 8;
		}
	}

	/* 32 bits of page counter (we have both counter and page header
	because this val can roll over) */
	if (os->pageno == -1)os->pageno = 0; /* because someone called
										 stream_reset; this would be a
										 strange thing to do in an
										 encode stream, but it has
										 plausible uses */
	{
		s32 pageno = os->pageno++;
		for (i = 18; i<22; i++) {
			os->header[i] = (pageno & 0xff);
			pageno >>= 8;
		}
	}

	/* zero for computation; filled in later */
	os->header[22] = 0;
	os->header[23] = 0;
	os->header[24] = 0;
	os->header[25] = 0;

	/* segment table */
	os->header[26] = vals & 0xff;
	for (i = 0; i<vals; i++)
		bytes += os->header[i + 27] = (os->lacing_vals[i] & 0xff);

	/* set pointers in the ogg_page struct */
	og->header = os->header;
	og->header_len = os->header_fill = vals + 27;
	og->body = os->body_data + os->body_returned;
	og->body_len = bytes;

	/* advance the lacing data and set the body_returned pointer */

	os->lacing_fill -= vals;
	memmove(os->lacing_vals, os->lacing_vals + vals, os->lacing_fill * sizeof(*os->lacing_vals));
	memmove(os->granule_vals, os->granule_vals + vals, os->lacing_fill * sizeof(*os->granule_vals));
	os->body_returned += bytes;

	/* calculate the checksum */

	ogg_page_checksum_set(og);

	/* done */
	return(1);
}


/* This constructs pages from buffered packet segments.  The pointers
returned are to static buffers; do not free. The returned buffers are
good only until the next call (using the same ogg_stream_state) */

s32 ogg_stream_pageout(ogg_stream_state *os, ogg_page *og) {

	if ((os->e_o_s&&os->lacing_fill) ||          /* 'were done, now flush' case */
		os->body_fill - os->body_returned > 4096 ||/* 'page nominal size' case */
		os->lacing_fill >= 255 ||                  /* 'segment table full' case */
		(os->lacing_fill && !os->b_o_s)) {         /* 'initial header page' case */

		return(ogg_stream_flush(os, og));
	}

	/* not enough data to construct a page and not end of stream */
	return(0);
}

s32 ogg_stream_eos(ogg_stream_state *os) {
	return os->e_o_s;
}

/* DECODING PRIMITIVES: packet streaming layer **********************/

/* This has two layers to place more of the multi-serialno and paging
control in the application's hands.  First, we expose a data buffer
using ogg_sync_buffer().  The app either copies into the
buffer, or passes it directly to read(), etc.  We then call
ogg_sync_wrote() to tell how many bytes we just added.

Pages are returned (pointers into the buffer in ogg_sync_state)
by ogg_sync_pageout().  The page is then submitted to
ogg_stream_pagein() along with the appropriate
ogg_stream_state* (ie, matching serialno).  We then get raw
packets out calling ogg_stream_packetout() with a
ogg_stream_state.  See the 'frame-prog.txt' docs for details and
example code. */

/* initialize the struct to a known state */
s32 ogg_sync_init(ogg_sync_state *oy) {
	if (oy) {
		memset(oy, 0, sizeof(*oy));
	}
	return(0);
}

/* clear non-flat storage within */
s32 ogg_sync_clear(ogg_sync_state *oy) {
	if (oy) {
		if (oy->data)gf_free(oy->data);
		ogg_sync_init(oy);
	}
	return(0);
}

s32 ogg_sync_destroy(ogg_sync_state *oy) {
	if (oy) {
		ogg_sync_clear(oy);
		gf_free(oy);
	}
	return(0);
}

char *ogg_sync_buffer(ogg_sync_state *oy, s32 size) {

	/* first, clear out any space that has been previously returned */
	if (oy->returned) {
		oy->fill -= oy->returned;
		if (oy->fill>0)
			memmove(oy->data, oy->data + oy->returned, oy->fill);
		oy->returned = 0;
	}

	if (size>oy->storage - oy->fill) {
		/* We need to extend the internal buffer */
		s32 newsize = size + oy->fill + 4096; /* an extra page to be nice */

		if (oy->data)
			oy->data = (unsigned char *)gf_realloc(oy->data, newsize);
		else
			oy->data = (unsigned char *)gf_malloc(newsize);
		oy->storage = newsize;
	}

	/* expose a segment at least as large as requested at the fill mark */
	return((char *)oy->data + oy->fill);
}

s32 ogg_sync_wrote(ogg_sync_state *oy, s32 bytes) {
	if (oy->fill + bytes>oy->storage)return(-1);
	oy->fill += bytes;
	return(0);
}

/* sync the stream.  This is meant to be useful for finding page
boundaries.

return values for this:
-n) skipped n bytes
0) page not ready; more data (no bytes skipped)
n) page synced at current location; page length n bytes

*/

s32 ogg_sync_pageseek(ogg_sync_state *oy, ogg_page *og) {
	unsigned char *page = oy->data + oy->returned;
	unsigned char *next;
	s32 bytes = oy->fill - oy->returned;

	if (oy->headerbytes == 0) {
		s32 headerbytes, i;
		if (bytes<27)return(0); /* not enough for a header */

								/* verify capture pattern */
		if (memcmp(page, "OggS", 4))goto sync_fail;

		headerbytes = page[26] + 27;
		if (bytes<headerbytes)return(0); /* not enough for header + seg table */

										 /* count up body length in the segment table */

		for (i = 0; i<page[26]; i++)
			oy->bodybytes += page[27 + i];
		oy->headerbytes = headerbytes;
	}

	if (oy->bodybytes + oy->headerbytes>bytes)return(0);

	/* The whole test page is buffered.  Verify the checksum */
	{
		/* Grab the checksum bytes, set the header field to zero */
		char chksum[4];
		ogg_page log;

		memcpy(chksum, page + 22, 4);
		memset(page + 22, 0, 4);

		/* set up a temp page struct and recompute the checksum */
		log.header = page;
		log.header_len = oy->headerbytes;
		log.body = page + oy->headerbytes;
		log.body_len = oy->bodybytes;
		ogg_page_checksum_set(&log);

		/* Compare */
		if (memcmp(chksum, page + 22, 4)) {
			/* D'oh.  Mismatch! Corrupt page (or miscapture and not a page
			at all) */
			/* replace the computed checksum with the one actually read in */
			memcpy(page + 22, chksum, 4);

			/* Bad checksum. Lose sync */
			goto sync_fail;
		}
	}

	/* yes, have a whole page all ready to go */
	{
		unsigned char *page = oy->data + oy->returned;
		s32 bytes;

		if (og) {
			og->header = page;
			og->header_len = oy->headerbytes;
			og->body = page + oy->headerbytes;
			og->body_len = oy->bodybytes;
		}

		oy->unsynced = 0;
		oy->returned += (bytes = oy->headerbytes + oy->bodybytes);
		oy->headerbytes = 0;
		oy->bodybytes = 0;
		return(bytes);
	}

sync_fail:

	oy->headerbytes = 0;
	oy->bodybytes = 0;

	/* search for possible capture */
	next = (unsigned char *)memchr(page + 1, 'O', bytes - 1);
	if (!next)
		next = oy->data + oy->fill;

	oy->returned = (s32)(next - oy->data);
	return (s32)(-(next - page));
}

/* sync the stream and get a page.  Keep trying until we find a page.
Supress 'sync errors' after reporting the first.

return values:
-1) recapture (hole in data)
0) need more data
1) page returned

Returns pointers into buffered data; invalidated by next call to
_stream, _clear, _init, or _buffer */

s32 ogg_sync_pageout(ogg_sync_state *oy, ogg_page *og) {

	/* all we need to do is verify a page at the head of the stream
	buffer.  If it doesn't verify, we look for the next potential
	frame */

	while (1) {
		s32 ret = ogg_sync_pageseek(oy, og);
		if (ret>0) {
			/* have a page */
			return(1);
		}
		if (ret == 0) {
			/* need more data */
			return(0);
		}

		/* head did not start a synced page... skipped some bytes */
		if (!oy->unsynced) {
			oy->unsynced = 1;
			return(-1);
		}

		/* loop. keep looking */

	}
}

/* add the incoming page to the stream state; we decompose the page
into packet segments here as well. */

s32 ogg_stream_pagein(ogg_stream_state *os, ogg_page *og) {
	unsigned char *header = og->header;
	unsigned char *body = og->body;
	s32           bodysize = og->body_len;
	s32            segptr = 0;

	s32 version = ogg_page_version(og);
	s32 continued = ogg_page_continued(og);
	s32 bos = ogg_page_bos(og);
	s32 eos = ogg_page_eos(og);
	s64 granulepos = ogg_page_granulepos(og);
	s32 serialno = ogg_page_serialno(og);
	s32 pageno = ogg_page_pageno(og);
	s32 segments = header[26];

	/* clean up 'returned data' */
	{
		s32 lr = os->lacing_returned;
		s32 br = os->body_returned;

		/* body data */
		if (br) {
			os->body_fill -= br;
			if (os->body_fill)
				memmove(os->body_data, os->body_data + br, os->body_fill);
			os->body_returned = 0;
		}

		if (lr) {
			/* segment table */
			if (os->lacing_fill - lr) {
				memmove(os->lacing_vals, os->lacing_vals + lr,
					(os->lacing_fill - lr) * sizeof(*os->lacing_vals));
				memmove(os->granule_vals, os->granule_vals + lr,
					(os->lacing_fill - lr) * sizeof(*os->granule_vals));
			}
			os->lacing_fill -= lr;
			os->lacing_packet -= lr;
			os->lacing_returned = 0;
		}
	}

	/* check the serial number */
	if (serialno != os->serialno)return(-1);
	if (version>0)return(-1);

	_os_lacing_expand(os, segments + 1);

	/* are we in sequence? */
	if (pageno != os->pageno) {
		s32 i;

		/* unroll previous partial packet (if any) */
		for (i = os->lacing_packet; i<os->lacing_fill; i++)
			os->body_fill -= os->lacing_vals[i] & 0xff;
		os->lacing_fill = os->lacing_packet;

		/* make a note of dropped data in segment table */
		if (os->pageno != -1) {
			os->lacing_vals[os->lacing_fill++] = 0x400;
			os->lacing_packet++;
		}

		/* are we a 'continued packet' page?  If so, we'll need to skip
		some segments */
		if (continued) {
			bos = 0;
			for (; segptr<segments; segptr++) {
				s32 val = header[27 + segptr];
				body += val;
				bodysize -= val;
				if (val<255) {
					segptr++;
					break;
				}
			}
		}
	}

	if (bodysize) {
		_os_body_expand(os, bodysize);
		memcpy(os->body_data + os->body_fill, body, bodysize);
		os->body_fill += bodysize;
	}

	{
		s32 saved = -1;
		while (segptr<segments) {
			s32 val = header[27 + segptr];
			os->lacing_vals[os->lacing_fill] = val;
			os->granule_vals[os->lacing_fill] = -1;

			if (bos) {
				os->lacing_vals[os->lacing_fill] |= 0x100;
				bos = 0;
			}

			if (val<255)saved = os->lacing_fill;

			os->lacing_fill++;
			segptr++;

			if (val<255)os->lacing_packet = os->lacing_fill;
		}

		/* set the granulepos on the last granuleval of the last full packet */
		if (saved != -1) {
			os->granule_vals[saved] = granulepos;
		}

	}

	if (eos) {
		os->e_o_s = 1;
		if (os->lacing_fill>0)
			os->lacing_vals[os->lacing_fill - 1] |= 0x200;
	}

	os->pageno = pageno + 1;

	return(0);
}

/* clear things to an initial state.  Good to call, eg, before seeking */
s32 ogg_sync_reset(ogg_sync_state *oy) {
	oy->fill = 0;
	oy->returned = 0;
	oy->unsynced = 0;
	oy->headerbytes = 0;
	oy->bodybytes = 0;
	return(0);
}

s32 ogg_stream_reset(ogg_stream_state *os) {
	os->body_fill = 0;
	os->body_returned = 0;

	os->lacing_fill = 0;
	os->lacing_packet = 0;
	os->lacing_returned = 0;

	os->header_fill = 0;

	os->e_o_s = 0;
	os->b_o_s = 0;
	os->pageno = -1;
	os->packetno = 0;
	os->granulepos = 0;

	return(0);
}

s32 ogg_stream_reset_serialno(ogg_stream_state *os, s32 serialno) {
	ogg_stream_reset(os);
	os->serialno = serialno;
	return(0);
}

static s32 _packetout(ogg_stream_state *os, ogg_packet *op, s32 adv) {

	/* The last part of decode. We have the stream broken into packet
	segments.  Now we need to group them into packets (or return the
	out of sync markers) */

	s32 ptr = os->lacing_returned;

	if (os->lacing_packet <= ptr)return(0);

	if (os->lacing_vals[ptr] & 0x400) {
		/* we need to tell the codec there's a gap; it might need to
		handle previous packet dependencies. */
		os->lacing_returned++;
		os->packetno++;
		return(-1);
	}

	if (!op && !adv)return(1); /* just using peek as an inexpensive way
							   to ask if there's a whole packet
							   waiting */

							   /* Gather the whole packet. We'll have no holes or a partial packet */
	{
		s32 size = os->lacing_vals[ptr] & 0xff;
		s32 bytes = size;
		s32 eos = os->lacing_vals[ptr] & 0x200; /* last packet of the stream? */
		s32 bos = os->lacing_vals[ptr] & 0x100; /* first packet of the stream? */

		while (size == 255) {
			s32 val = os->lacing_vals[++ptr];
			size = val & 0xff;
			if (val & 0x200)eos = 0x200;
			bytes += size;
		}

		if (op) {
			op->e_o_s = eos;
			op->b_o_s = bos;
			op->packet = os->body_data + os->body_returned;
			op->packetno = os->packetno;
			op->granulepos = os->granule_vals[ptr];
			op->bytes = bytes;
		}

		if (adv) {
			os->body_returned += bytes;
			os->lacing_returned = ptr + 1;
			os->packetno++;
		}
	}
	return(1);
}

s32 ogg_stream_packetout(ogg_stream_state *os, ogg_packet *op) {
	return _packetout(os, op, 1);
}

s32 ogg_stream_packetpeek(ogg_stream_state *os, ogg_packet *op) {
	return _packetout(os, op, 0);
}

void ogg_packet_clear(ogg_packet *op) {
	gf_free(op->packet);
	memset(op, 0, sizeof(*op));
}

#endif /*GPAC_DISABLE_OGG*/