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gstreamer/gst-libs/gst/mpegts/gstmpegtsdescriptor.c
Edward Hervey f24c0b62e3 mpegts: Improve documentation 
* Add a base page for the library
* Add pages for the base MPEG-TS section and descriptors
* Add pages for the known variants
* Add documentation on more fields/sections/types
* Remove some fixmes that were ... fixed
2013-07-04 08:45:33 +02:00

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/*
* gstmpegtsdescriptor.c -
* Copyright (C) 2013 Edward Hervey
*
* Authors:
* Edward Hervey <edward@collabora.com>
*
* 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., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include <stdlib.h>
#include <string.h>
#include "mpegts.h"
#include "gstmpegts-private.h"
/**
* SECTION:gstmpegtsdescriptor
* @title: Base MPEG-TS descriptors
* @short_description: Descriptors for ITU H.222.0 | ISO/IEC 13818-1
* @include: gst/mpegts/mpegts.h
*
* These are the base descriptor types and methods.
*
* For more details, refer to the ITU H.222.0 or ISO/IEC 13818-1 specifications
* and other specifications mentionned in the documentation.
*/
/* FIXME : Move this to proper file once we have a C file for ATSC/ISDB descriptors */
/**
* SECTION:gst-atsc-descriptor
* @title: ATSC variants of MPEG-TS descriptors
* @short_description: Descriptors for the various ATSC specifications
* @include: gst/mpegts/mpegts.h
*
*/
/**
* SECTION:gst-isdb-descriptor
* @title: ISDB variants of MPEG-TS descriptors
* @short_description: Descriptors for the various ISDB specifications
* @include: gst/mpegts/mpegts.h
*
*/
/*
* TODO
*
* * Add common validation code for data presence and minimum/maximum expected
* size.
* * Add parsing methods for the following descriptors that were previously
* handled in mpegtsbase:
* * GST_MTS_DESC_DVB_DATA_BROADCAST_ID
* * GST_MTS_DESC_DVB_DATA_BROADCAST
* * GST_MTS_DESC_DVB_CAROUSEL_IDENTIFIER
* * GST_MTS_DESC_DVB_STREAM_IDENTIFIER
* * GST_MTS_DESC_DVB_EXTENDED_EVENT
* * GST_MTS_DESC_DVB_COMPONENT
* * GST_MTS_DESC_DVB_TERRESTRIAL_DELIVERY_SYSTEM
* * GST_MTS_DESC_DVB_FREQUENCY_LIST
*/
#define MAX_KNOWN_ICONV 25
static GIConv __iconvs[MAX_KNOWN_ICONV];
/* All these conversions will be to UTF8 */
typedef enum
{
_ICONV_UNKNOWN = -1,
_ICONV_ISO8859_1,
_ICONV_ISO8859_2,
_ICONV_ISO8859_3,
_ICONV_ISO8859_4,
_ICONV_ISO8859_5,
_ICONV_ISO8859_6,
_ICONV_ISO8859_7,
_ICONV_ISO8859_8,
_ICONV_ISO8859_9,
_ICONV_ISO8859_10,
_ICONV_ISO8859_11,
_ICONV_ISO8859_12,
_ICONV_ISO8859_13,
_ICONV_ISO8859_14,
_ICONV_ISO8859_15,
_ICONV_ISO10646_UC2,
_ICONV_EUC_KR,
_ICONV_GB2312,
_ICONV_UTF_16BE,
_ICONV_ISO10646_UTF8,
_ICONV_ISO6937,
/* Insert more here if needed */
_ICONV_MAX
} LocalIconvCode;
static const gchar *iconvtablename[] = {
"iso-8859-1",
"iso-8859-2",
"iso-8859-3",
"iso-8859-4",
"iso-8859-5",
"iso-8859-6",
"iso-8859-7",
"iso-8859-8",
"iso-8859-9",
"iso-8859-10",
"iso-8859-11",
"iso-8859-12",
"iso-8859-13",
"iso-8859-14",
"iso-8859-15",
"ISO-10646/UCS2",
"EUC-KR",
"GB2312",
"UTF-16BE",
"ISO-10646/UTF8",
"iso6937"
/* Insert more here if needed */
};
void
__initialize_descriptors (void)
{
guint i;
/* Initialize converters */
/* FIXME : How/when should we close them ??? */
for (i = 0; i < MAX_KNOWN_ICONV; i++)
__iconvs[i] = ((GIConv) - 1);
}
/*
* @text: The text you want to get the encoding from
* @start_text: Location where the beginning of the actual text is stored
* @is_multibyte: Location where information whether it's a multibyte encoding
* or not is stored
* @returns: GIconv for conversion or NULL
*/
static LocalIconvCode
get_encoding (const gchar * text, guint * start_text, gboolean * is_multibyte)
{
LocalIconvCode encoding;
guint8 firstbyte;
*is_multibyte = FALSE;
*start_text = 0;
firstbyte = (guint8) text[0];
/* A wrong value */
g_return_val_if_fail (firstbyte != 0x00, _ICONV_UNKNOWN);
if (firstbyte <= 0x0B) {
/* 0x01 => iso 8859-5 */
encoding = firstbyte + _ICONV_ISO8859_4;
*start_text = 1;
goto beach;
}
/* ETSI EN 300 468, "Selection of character table" */
switch (firstbyte) {
case 0x0C:
case 0x0D:
case 0x0E:
case 0x0F:
/* RESERVED */
encoding = _ICONV_UNKNOWN;
break;
case 0x10:
{
guint16 table;
table = GST_READ_UINT16_BE (text + 1);
if (table < 17)
encoding = _ICONV_UNKNOWN + table;
else
encoding = _ICONV_UNKNOWN;;
*start_text = 3;
break;
}
case 0x11:
encoding = _ICONV_ISO10646_UC2;
*start_text = 1;
*is_multibyte = TRUE;
break;
case 0x12:
/* EUC-KR implements KSX1001 */
encoding = _ICONV_EUC_KR;
*start_text = 1;
*is_multibyte = TRUE;
break;
case 0x13:
encoding = _ICONV_GB2312;
*start_text = 1;
break;
case 0x14:
encoding = _ICONV_UTF_16BE;
*start_text = 1;
*is_multibyte = TRUE;
break;
case 0x15:
/* TODO : Where does this come from ?? */
encoding = _ICONV_ISO10646_UTF8;
*start_text = 1;
break;
case 0x16:
case 0x17:
case 0x18:
case 0x19:
case 0x1A:
case 0x1B:
case 0x1C:
case 0x1D:
case 0x1E:
case 0x1F:
/* RESERVED */
encoding = _ICONV_UNKNOWN;
break;
default:
encoding = _ICONV_ISO6937;
break;
}
beach:
GST_DEBUG
("Found encoding %d, first byte is 0x%02x, start_text: %u, is_multibyte: %d",
encoding, firstbyte, *start_text, *is_multibyte);
return encoding;
}
/*
* @text: The text to convert. It may include pango markup (<b> and </b>)
* @length: The length of the string -1 if it's nul-terminated
* @start: Where to start converting in the text
* @encoding: The encoding of text
* @is_multibyte: Whether the encoding is a multibyte encoding
* @error: The location to store the error, or NULL to ignore errors
* @returns: UTF-8 encoded string
*
* Convert text to UTF-8.
*/
static gchar *
convert_to_utf8 (const gchar * text, gint length, guint start,
GIConv giconv, gboolean is_multibyte, GError ** error)
{
gchar *new_text;
gchar *tmp, *pos;
gint i;
text += start;
pos = tmp = g_malloc (length * 2);
if (is_multibyte) {
if (length == -1) {
while (*text != '\0') {
guint16 code = GST_READ_UINT16_BE (text);
switch (code) {
case 0xE086: /* emphasis on */
case 0xE087: /* emphasis off */
/* skip it */
break;
case 0xE08A:{
pos[0] = 0x00; /* 0x00 0x0A is a new line */
pos[1] = 0x0A;
pos += 2;
break;
}
default:
pos[0] = text[0];
pos[1] = text[1];
pos += 2;
break;
}
text += 2;
}
} else {
for (i = 0; i < length; i += 2) {
guint16 code = GST_READ_UINT16_BE (text);
switch (code) {
case 0xE086: /* emphasis on */
case 0xE087: /* emphasis off */
/* skip it */
break;
case 0xE08A:{
pos[0] = 0x00; /* 0x00 0x0A is a new line */
pos[1] = 0x0A;
pos += 2;
break;
}
default:
pos[0] = text[0];
pos[1] = text[1];
pos += 2;
break;
}
text += 2;
}
}
} else {
if (length == -1) {
while (*text != '\0') {
guint8 code = (guint8) (*text);
switch (code) {
case 0x86: /* emphasis on */
case 0x87: /* emphasis off */
/* skip it */
break;
case 0x8A:
*pos = '\n';
pos += 1;
break;
default:
*pos = *text;
pos += 1;
break;
}
text++;
}
} else {
for (i = 0; i < length; i++) {
guint8 code = (guint8) (*text);
switch (code) {
case 0x86: /* emphasis on */
case 0x87: /* emphasis off */
/* skip it */
break;
case 0x8A:
*pos = '\n';
pos += 1;
break;
default:
*pos = *text;
pos += 1;
break;
}
text++;
}
}
}
if (pos > tmp) {
gsize bread = 0;
new_text =
g_convert_with_iconv (tmp, pos - tmp, giconv, &bread, NULL, error);
GST_DEBUG ("Converted to : %s", new_text);
} else {
new_text = g_strdup ("");
}
g_free (tmp);
return new_text;
}
gchar *
get_encoding_and_convert (const gchar * text, guint length)
{
GError *error = NULL;
gchar *converted_str;
guint start_text = 0;
gboolean is_multibyte;
LocalIconvCode encoding;
GIConv giconv = (GIConv) - 1;
g_return_val_if_fail (text != NULL, NULL);
if (text == NULL || length == 0)
return g_strdup ("");
encoding = get_encoding (text, &start_text, &is_multibyte);
if (encoding > _ICONV_UNKNOWN && encoding < _ICONV_MAX) {
GST_DEBUG ("Encoding %s", iconvtablename[encoding]);
if (__iconvs[encoding] == ((GIConv) - 1))
__iconvs[encoding] = g_iconv_open ("utf-8", iconvtablename[encoding]);
giconv = __iconvs[encoding];
} else {
GST_FIXME ("Could not detect encoding. Returning NULL string");
converted_str = NULL;
goto beach;
}
converted_str = convert_to_utf8 (text, length - start_text, start_text,
giconv, is_multibyte, &error);
if (error != NULL) {
GST_WARNING ("Could not convert string: %s", error->message);
if (converted_str)
g_free (converted_str);
g_error_free (error);
error = NULL;
if (encoding >= _ICONV_ISO8859_2 && encoding <= _ICONV_ISO8859_15) {
/* Sometimes using the standard 8859-1 set fixes issues */
GST_DEBUG ("Encoding %s", iconvtablename[_ICONV_ISO8859_1]);
if (__iconvs[_ICONV_ISO8859_1] == (GIConv) - 1)
__iconvs[_ICONV_ISO8859_1] =
g_iconv_open ("utf-8", iconvtablename[_ICONV_ISO8859_1]);
giconv = __iconvs[_ICONV_ISO8859_1];
GST_INFO ("Trying encoding ISO 8859-1");
converted_str = convert_to_utf8 (text, length, 1, giconv, FALSE, &error);
if (error != NULL) {
GST_WARNING
("Could not convert string while assuming encoding ISO 8859-1: %s",
error->message);
g_error_free (error);
goto failed;
}
} else if (encoding == _ICONV_ISO6937) {
/* The first part of ISO 6937 is identical to ISO 8859-9, but
* they differ in the second part. Some channels don't
* provide the first byte that indicates ISO 8859-9 encoding.
* If decoding from ISO 6937 failed, we try ISO 8859-9 here.
*/
if (__iconvs[_ICONV_ISO8859_9] == (GIConv) - 1)
__iconvs[_ICONV_ISO8859_9] =
g_iconv_open ("utf-8", iconvtablename[_ICONV_ISO8859_9]);
giconv = __iconvs[_ICONV_ISO8859_9];
GST_INFO ("Trying encoding ISO 8859-9");
converted_str = convert_to_utf8 (text, length, 0, giconv, FALSE, &error);
if (error != NULL) {
GST_WARNING
("Could not convert string while assuming encoding ISO 8859-9: %s",
error->message);
g_error_free (error);
goto failed;
}
} else
goto failed;
}
beach:
return converted_str;
failed:
{
text += start_text;
return g_strndup (text, length - start_text);
}
}
/**
* gst_mpegts_parse_descriptors:
* @buffer: (transfer none): descriptors to parse
* @buf_len: Size of @buffer
*
* Parses the descriptors present in @buffer and returns them as an
* array.
*
* Note: The data provided in @buffer will not be copied.
*
* Returns: (transfer full) (element-type GstMpegTsDescriptor): an
* array of the parsed descriptors or %NULL if there was an error.
* Release with #g_array_unref when done with it.
*/
GArray *
gst_mpegts_parse_descriptors (guint8 * buffer, gsize buf_len)
{
GArray *res;
guint8 length;
guint8 *data;
guint i, nb_desc = 0;
/* fast-path */
if (buf_len == 0)
return g_array_new (FALSE, FALSE, sizeof (GstMpegTsDescriptor));
data = buffer;
while (data - buffer < buf_len) {
data++; /* skip tag */
length = *data++;
if (data - buffer > buf_len) {
GST_WARNING ("invalid descriptor length %d now at %d max %"
G_GSIZE_FORMAT, length, (gint) (data - buffer), buf_len);
return NULL;
}
data += length;
nb_desc++;
}
GST_DEBUG ("Saw %d descriptors, read %" G_GSIZE_FORMAT " bytes",
nb_desc, data - buffer);
if (data - buffer != buf_len) {
GST_WARNING ("descriptors size %d expected %" G_GSIZE_FORMAT,
(gint) (data - buffer), buf_len);
return NULL;
}
res = g_array_sized_new (FALSE, FALSE, sizeof (GstMpegTsDescriptor), nb_desc);
data = buffer;
for (i = 0; i < nb_desc; i++) {
GstMpegTsDescriptor *desc = &g_array_index (res, GstMpegTsDescriptor, i);
desc->descriptor_data = data;
desc->descriptor_tag = *data++;
desc->descriptor_length = *data++;
GST_LOG ("descriptor 0x%02x length:%d", desc->descriptor_tag,
desc->descriptor_length);
GST_MEMDUMP ("descriptor", desc->descriptor_data + 2,
desc->descriptor_length);
/* Adjust for extended descriptors */
if (G_UNLIKELY (desc->descriptor_tag == 0x7f)) {
desc->descriptor_tag_extension = *data++;
desc->descriptor_length -= 1;
}
data += desc->descriptor_length;
}
res->len = nb_desc;
return res;
}
/**
* gst_mpegts_find_descriptor:
* @descriptors: (element-type GstMpegTsDescriptor) (transfer none): an array
* of #GstMpegTsDescriptor
* @tag: the tag to look for
*
* Finds the first descriptor of type @tag in the array.
*
* Note: To look for descriptors that can be present more than once in an
* array of descriptors, iterate the #GArray manually.
*
* Returns: (transfer none): the first descriptor matchin @tag, else %NULL.
*/
const GstMpegTsDescriptor *
gst_mpegts_find_descriptor (GArray * descriptors, guint8 tag)
{
guint i, nb_desc;
g_return_val_if_fail (descriptors != NULL, NULL);
nb_desc = descriptors->len;
for (i = 0; i < nb_desc; i++) {
GstMpegTsDescriptor *desc =
&g_array_index (descriptors, GstMpegTsDescriptor, i);
if (desc->descriptor_tag == tag)
return (const GstMpegTsDescriptor *) desc;
}
return NULL;
}
static GstMpegTsDescriptor *
_copy_descriptor (GstMpegTsDescriptor * desc)
{
GstMpegTsDescriptor *copy;
copy = g_new0 (GstMpegTsDescriptor, 1);
copy->descriptor_tag = desc->descriptor_tag;
copy->descriptor_tag_extension = desc->descriptor_tag_extension;
copy->descriptor_length = desc->descriptor_length;
copy->descriptor_data =
g_memdup (desc->descriptor_data, desc->descriptor_length);
return copy;
}
/* This freefunc will only ever be used with descriptors returned by the
* above function. That is why we free the descriptor data (unlike the
* descriptors created in _parse_descriptors()) */
static void
_free_descriptor (GstMpegTsDescriptor * desc)
{
g_free ((gpointer) desc->descriptor_data);
g_free (desc);
}
G_DEFINE_BOXED_TYPE (GstMpegTsDescriptor, gst_mpegts_descriptor,
(GBoxedCopyFunc) _copy_descriptor, (GBoxedFreeFunc) _free_descriptor);
/* GST_MTS_DESC_ISO_639_LANGUAGE (0x0A) */
/**
* gst_mpegts_descriptor_parse_iso_639_language:
* @descriptor: a %GST_MTS_DESC_ISO_639_LANGUAGE #GstMpegTsDescriptor
* @res: (out) (transfer none): the #GstMpegTsISO639LanguageDescriptor to fill
*
* Extracts the iso 639-2 language information from @descriptor.
*
* Note: Use #gst_tag_get_language_code if you want to get the the
* ISO 639-1 language code from the returned ISO 639-2 one.
*
* Returns: %TRUE if parsing succeeded, else %FALSE.
*/
gboolean
gst_mpegts_descriptor_parse_iso_639_language (const GstMpegTsDescriptor *
descriptor, GstMpegTsISO639LanguageDescriptor * res)
{
guint i;
guint8 *data;
g_return_val_if_fail (descriptor != NULL
&& descriptor->descriptor_data != NULL, FALSE);
g_return_val_if_fail (res != NULL, FALSE);
g_return_val_if_fail (descriptor->descriptor_tag == 0x0A, FALSE);
data = (guint8 *) descriptor->descriptor_data + 2;
/* Each language is 3 + 1 bytes */
res->nb_language = descriptor->descriptor_length / 4;
for (i = 0; i < res->nb_language; i++) {
memcpy (res->language[i], data, 3);
res->audio_type[i] = data[3];
data += 4;
}
return TRUE;
}
/**
* gst_mpegts_descriptor_parse_logical_channel:
* @descriptor: a %GST_MTS_DESC_DTG_LOGICAL_CHANNEL #GstMpegTsDescriptor
* @res: (out) (transfer none): the #GstMpegTsLogicalChannelDescriptor to fill
*
* Extracts the logical channels from @descriptor.
*
* Returns: %TRUE if parsing succeeded, else %FALSE.
*/
gboolean
gst_mpegts_descriptor_parse_logical_channel (const GstMpegTsDescriptor *
descriptor, GstMpegTsLogicalChannelDescriptor * res)
{
guint i;
guint8 *data;
g_return_val_if_fail (descriptor != NULL
&& descriptor->descriptor_data != NULL, FALSE);
g_return_val_if_fail (descriptor->descriptor_tag == 0x83, FALSE);
data = (guint8 *) descriptor->descriptor_data;
res->nb_channels = descriptor->descriptor_length / 4;
for (i = 0; i < res->nb_channels; i++) {
res->channels[i].service_id = GST_READ_UINT16_BE (data);
data += 2;
res->channels[i].visible_service = *data >> 7;
res->channels[i].logical_channel_number =
GST_READ_UINT16_BE (data) & 0x03ff;
data += 2;
}
return TRUE;
}
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