gstreamer/gst/realmedia/rmutils.c

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/* GStreamer RealMedia utility functions
* Copyright (C) 2006 Tim-Philipp Müller <tim centricular net>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <string.h>
#include "rmutils.h"
gchar *
gst_rm_utils_read_string8 (const guint8 * data, guint datalen,
guint * p_total_len)
{
gint length;
if (p_total_len)
*p_total_len = 0;
if (datalen < 1)
return NULL;
length = GST_READ_UINT8 (data);
if (datalen < (1 + length))
return NULL;
if (p_total_len)
*p_total_len = 1 + length;
return g_strndup ((gchar *) data + 1, length);
}
gchar *
gst_rm_utils_read_string16 (const guint8 * data, guint datalen,
guint * p_total_len)
{
gint length;
if (p_total_len)
*p_total_len = 0;
if (datalen < 2)
return NULL;
length = GST_READ_UINT16_BE (data);
if (datalen < (2 + length))
return NULL;
if (p_total_len)
*p_total_len = 2 + length;
return g_strndup ((gchar *) data + 2, length);
}
GstTagList *
gst_rm_utils_read_tags (const guint8 * data, guint datalen,
GstRmUtilsStringReadFunc read_string_func)
{
const gchar *gst_tags[] = { GST_TAG_TITLE, GST_TAG_ARTIST,
GST_TAG_COPYRIGHT, GST_TAG_COMMENT
};
GstTagList *tags;
guint i;
g_assert (read_string_func != NULL);
GST_DEBUG ("File Content : (CONT) len = %d", datalen);
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tags = gst_tag_list_new_empty ();
for (i = 0; i < G_N_ELEMENTS (gst_tags); ++i) {
gchar *str = NULL;
guint total_length = 0;
str = read_string_func (data, datalen, &total_length);
data += total_length;
datalen -= total_length;
if (str != NULL && !g_utf8_validate (str, -1, NULL)) {
const gchar *encoding;
gchar *tmp;
encoding = g_getenv ("GST_TAG_ENCODING");
if (encoding == NULL || *encoding == '\0') {
if (g_get_charset (&encoding))
encoding = "ISO-8859-15";
}
GST_DEBUG ("converting tag from %s to UTF-8", encoding);
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tmp = g_convert_with_fallback (str, -1, "UTF-8", encoding, (gchar *) "*",
NULL, NULL, NULL);
g_free (str);
str = tmp;
}
GST_DEBUG ("%s = %s", gst_tags[i], GST_STR_NULL (str));
if (str != NULL && *str != '\0') {
gst_tag_list_add (tags, GST_TAG_MERGE_APPEND, gst_tags[i], str, NULL);
}
g_free (str);
}
if (gst_structure_n_fields ((GstStructure *) tags) > 0)
return tags;
gst_tag_list_free (tags);
return NULL;
}
GstBuffer *
gst_rm_utils_descramble_dnet_buffer (GstBuffer * buf)
{
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GstMapInfo map;
guint8 *data, *end, tmp;
buf = gst_buffer_make_writable (buf);
/* dnet = byte-order swapped AC3 */
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gst_buffer_map (buf, &map, GST_MAP_READWRITE);
data = map.data;
end = data + map.size;
while ((data + 1) < end) {
/* byte-swap */
tmp = data[0];
data[0] = data[1];
data[1] = tmp;
data += sizeof (guint16);
}
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gst_buffer_unmap (buf, &map);
return buf;
}
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static void
gst_rm_utils_swap_nibbles (guint8 * data, gint idx1, gint idx2, gint len)
{
guint8 *d1, *d2, tmp1 = 0, tmp2, tmp1n, tmp2n;
if ((idx2 & 1) && !(idx1 & 1)) {
/* align destination to a byte by swapping the indexes */
tmp1 = idx1;
idx1 = idx2;
idx2 = tmp1;
}
d1 = data + (idx1 >> 1);
d2 = data + (idx2 >> 1);
/* check if we have aligned offsets and we can copy bytes */
if ((idx1 & 1) == (idx2 & 1)) {
if (idx1 & 1) {
/* swap first nibble */
tmp1 = *d1;
tmp2 = *d2;
*d1++ = (tmp2 & 0xf0) | (tmp1 & 0x0f);
*d2++ = (tmp1 & 0xf0) | (tmp2 & 0x0f);
len--;
}
for (; len > 1; len -= 2) {
/* swap 2 nibbles */
tmp1 = *d1;
*d1++ = *d2;
*d2++ = tmp1;
}
if (len) {
/* swap leftover nibble */
tmp1 = *d1;
tmp2 = *d2;
*d1 = (tmp2 & 0x0f) | (tmp1 & 0xf0);
*d2 = (tmp1 & 0x0f) | (tmp2 & 0xf0);
}
} else {
/* preload nibbles from source */
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tmp2n = *d1;
tmp2 = *d2;
for (; len > 1; len -= 2) {
/* assemble nibbles */
*d1++ = (tmp2n & 0x0f) | (tmp2 << 4);
tmp1n = *d1;
*d2++ = (tmp1n << 4) | (tmp1 >> 4);
tmp1 = tmp1n;
tmp2n = (tmp2 >> 4);
tmp2 = *d2;
}
if (len) {
/* last leftover */
*d1 = (tmp2 << 4) | (tmp2n & 0x0f);
*d2 = (tmp1 >> 4) | (tmp2 & 0xf0);
} else {
*d1 = (tmp1 & 0xf0) | (tmp2n);
}
}
}
static const gint sipr_swap_index[38][2] = {
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{0, 63}, {1, 22}, {2, 44}, {3, 90},
{5, 81}, {7, 31}, {8, 86}, {9, 58},
{10, 36}, {12, 68}, {13, 39}, {14, 73},
{15, 53}, {16, 69}, {17, 57}, {19, 88},
{20, 34}, {21, 71}, {24, 46}, {25, 94},
{26, 54}, {28, 75}, {29, 50}, {32, 70},
{33, 92}, {35, 74}, {38, 85}, {40, 56},
{42, 87}, {43, 65}, {45, 59}, {48, 79},
{49, 93}, {51, 89}, {55, 95}, {61, 76},
{67, 83}, {77, 80}
};
GstBuffer *
gst_rm_utils_descramble_sipr_buffer (GstBuffer * buf)
{
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GstMapInfo map;
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gint n, bs;
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gsize size;
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size = gst_buffer_get_size (buf);
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/* split the packet in 96 blocks of nibbles */
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bs = size * 2 / 96;
if (bs == 0)
return buf;
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buf = gst_buffer_make_writable (buf);
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gst_buffer_map (buf, &map, GST_MAP_WRITE);
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/* we need to perform 38 swaps on the blocks */
for (n = 0; n < 38; n++) {
gint idx1, idx2;
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/* get the indexes of the blocks of nibbles that need swapping */
idx1 = bs * sipr_swap_index[n][0];
idx2 = bs * sipr_swap_index[n][1];
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/* swap the blocks */
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gst_rm_utils_swap_nibbles (map.data, idx1, idx2, bs);
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}
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gst_buffer_unmap (buf, &map);
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return buf;
}
void
gst_rm_utils_run_tests (void)
{
#if 0
guint8 tab1[] = { 0x10, 0x32, 0x54, 0x76, 0x98, 0xba, 0xdc, 0xfe };
guint8 tab2[8];
memcpy (tab2, tab1, 8);
gst_util_dump_mem (tab2, 8);
gst_rm_utils_swap_nibbles (tab2, 0, 8, 4);
gst_util_dump_mem (tab2, 8);
memcpy (tab2, tab1, 8);
gst_rm_utils_swap_nibbles (tab2, 0, 8, 5);
gst_util_dump_mem (tab2, 8);
memcpy (tab2, tab1, 8);
gst_rm_utils_swap_nibbles (tab2, 1, 8, 4);
gst_util_dump_mem (tab2, 8);
memcpy (tab2, tab1, 8);
gst_rm_utils_swap_nibbles (tab2, 1, 8, 5);
gst_util_dump_mem (tab2, 8);
memcpy (tab2, tab1, 8);
gst_rm_utils_swap_nibbles (tab2, 0, 9, 4);
gst_util_dump_mem (tab2, 8);
memcpy (tab2, tab1, 8);
gst_rm_utils_swap_nibbles (tab2, 0, 9, 5);
gst_util_dump_mem (tab2, 8);
memcpy (tab2, tab1, 8);
gst_rm_utils_swap_nibbles (tab2, 1, 9, 4);
gst_util_dump_mem (tab2, 8);
memcpy (tab2, tab1, 8);
gst_rm_utils_swap_nibbles (tab2, 1, 9, 5);
gst_util_dump_mem (tab2, 8);
#endif
}