/*****************************************************************************
* xiph.h: Xiph helpers
*****************************************************************************
* Copyright (C) 2010 Laurent Aimar
*
* Authors: Laurent Aimar <fenrir _AT_ videolan _DOT_ org>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
*****************************************************************************/
#include <assert.h>
#include <limits.h>
#define XIPH_MAX_HEADER_COUNT (
256)
/* Temp ffmpeg vorbis format */
static inline bool xiph_IsLavcFormat(
const void *extra, size_t i_extra,
vlc_fourcc_t i_codec)
{
switch(i_codec)
{
case VLC_CODEC_VORBIS:
return i_extra >=
6 && GetWBE(extra) ==
30;
case VLC_CODEC_THEORA:
return i_extra >=
6 && GetWBE(extra) ==
42;
default:
return false;
}
}
static inline unsigned xiph_CountLavcHeaders(
const void *p_extra, size_t i_extra)
{
const uint8_t *p = (
const uint8_t*) p_extra;
const uint8_t *p_end = &p[i_extra];
/* Check headers count */
for (
int i=
0; i<
3; i++)
{
if(p_end - p <
2)
return 0;
uint16_t i_size = GetWBE(p);
if(&p[
2U + i_size] > p_end)
return 0;
p +=
2 + i_size;
}
return 3;
}
static inline unsigned xiph_CountHeaders(
const void *p_extra, size_t i_extra)
{
const uint8_t *p = (
const uint8_t*) p_extra;
if (!i_extra)
return 0;
/* First byte is headers count */
if(
1U + *p > i_extra)
return 0;
return *p +
1;
}
static inline unsigned xiph_CountUnknownHeaders(
const void *p_extra,
unsigned i_extra,
vlc_fourcc_t i_codec)
{
if (xiph_IsLavcFormat(p_extra, i_extra, i_codec))
return xiph_CountLavcHeaders(p_extra, i_extra);
else
return xiph_CountHeaders(p_extra, i_extra);
}
static inline int xiph_SplitLavcHeaders(size_t packet_size[],
const void *packet[], size_t *packet_count,
size_t i_extra,
const void *p_extra)
{
const uint8_t *current = (
const uint8_t *)p_extra;
const uint8_t *end = ¤t[i_extra];
if (i_extra <
2)
return VLC_EGENERIC;
/* Parse the packet count and their sizes */
const unsigned count = xiph_CountLavcHeaders(current, i_extra);
if(count ==
0)
return VLC_EGENERIC;
if (packet_count)
*packet_count = count;
/* count is trusted here (xiph_CountHeaders) */
for (
unsigned i=
0; i < count; i++)
{
/* each payload is prefixed by word size */
packet_size[i] = GetWBE(current);
if(¤t[
2U + packet_size[i]] > end)
return VLC_EGENERIC;
packet[i] = current +
2;
current += packet_size[i] +
2;
}
return VLC_SUCCESS;
}
static inline int xiph_SplitHeaders(size_t packet_size[],
const void *packet[], size_t *packet_count,
size_t i_extra,
const void *p_extra)
{
const uint8_t *current = (
const uint8_t *)p_extra;
const uint8_t *end = ¤t[i_extra];
if (i_extra <
1)
return VLC_EGENERIC;
/* Parse the packet count and their sizes */
const unsigned count = xiph_CountHeaders(current, i_extra);
if(count ==
0)
return VLC_EGENERIC;
if (packet_count)
*packet_count = count;
/* - 1 byte (N-1) packets
* - N-1 variable length payload sizes
* - N-1 payloads
* - Nth packet (remaining) */
/* skip count byte header */
++current;
/* read sizes for N-1 packets */
unsigned total_payload_minus_last =
0;
for (
unsigned i =
0; i < count -
1; i++)
{
packet_size[i] =
0;
for (;;) {
if (current >= end)
return VLC_EGENERIC;
packet_size[i] += *current;
if (*current++ !=
255)
break;
}
if(UINT_MAX - total_payload_minus_last < packet_size[i])
return VLC_EGENERIC;
total_payload_minus_last += packet_size[i];
}
if(current + total_payload_minus_last > end)
return VLC_EGENERIC;
/* set pointers for N-1 packets */
for (
unsigned i =
0; i < count -
1; i++)
{
packet[i] = current;
current += packet_size[i];
}
/* Last packet is remaining size */
packet_size[count -
1] = end - current;
packet[count -
1] = current;
return VLC_SUCCESS;
}
static inline int xiph_PackHeaders(size_t *extra_size,
void **extra,
size_t packet_size[],
const void *
const packet[],
size_t packet_count)
{
if (packet_count <=
0 || packet_count > XIPH_MAX_HEADER_COUNT)
return VLC_EGENERIC;
/* Compute the size needed for the whole extra data */
size_t payload_size =
0;
size_t header_size =
1;
for (size_t i =
0; i < packet_count; i++) {
payload_size += packet_size[i];
if (i < packet_count -
1)
header_size +=
1 + packet_size[i] /
255;
}
/* */
*extra_size = header_size + payload_size;
*extra = malloc(*extra_size);
if (*extra == NULL)
return VLC_ENOMEM;
/* Write the header */
uint8_t *current = (uint8_t*)*extra;
*current++ = packet_count -
1;
for (size_t i =
0; i < packet_count -
1; i++) {
size_t t = packet_size[i];
for (;;) {
if (t >=
255) {
*current++ =
255;
t -=
255;
}
else {
*current++ = t;
break;
}
}
}
/* Copy the payloads */
for (size_t i =
0; i < packet_count; i++) {
if (packet_size[i] >
0) {
memcpy(current, packet[i], packet_size[i]);
current += packet_size[i];
}
}
assert(current == (uint8_t*)*extra + *extra_size);
return VLC_SUCCESS;
}
static inline int xiph_AppendHeaders(size_t *extra_size,
void **extra,
size_t size,
const void *data)
{
size_t packet_size[XIPH_MAX_HEADER_COUNT];
const void *packet[XIPH_MAX_HEADER_COUNT];
size_t count;
if (*extra_size >
0 && *extra) {
if (xiph_SplitHeaders(packet_size, packet, &count, *extra_size, *extra))
return VLC_EGENERIC;
}
else {
count =
0;
}
if (count >= XIPH_MAX_HEADER_COUNT)
return VLC_EGENERIC;
void *old = *extra;
packet_size[count] = size;
packet[count] = (
void*)data;
if (xiph_PackHeaders(extra_size, extra, packet_size,
packet, count +
1)) {
*extra_size =
0;
*extra = NULL;
}
free(old);
if (*extra_size ==
0)
return VLC_EGENERIC;
return VLC_SUCCESS;
}
