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/* GStreamer
* Copyright (C) <2008> Wim Taymans <wim.taymans@gmail.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., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include <string.h>
#include <stdlib.h>
#include "gstrtpchannels.h"
/*
* RTP channel positions as discussed in RFC 3551 and also RFC 3555
*
* We can't really represent the described channel positions in GStreamer but we
* implement a (very rough) approximation here.
*/
static gboolean
check_channels (const GstRTPChannelOrder * order,
const GstAudioChannelPosition * pos)
{
gint i;
gboolean res = TRUE;
for (i = 0; i < order->channels; i++) {
if (order->pos[i] != pos[i]) {
res = FALSE;
break;
}
}
return res;
}
/**
* gst_rtp_channels_get_by_pos:
* @channels: the amount of channels
* @pos: a channel layout
*
* Return a description of the channel layout.
*
* Returns: a #GstRTPChannelOrder with the channel information or NULL when @pos
* is not a valid layout.
*/
const GstRTPChannelOrder *
gst_rtp_channels_get_by_pos (gint channels, const GstAudioChannelPosition * pos)
{
gint i;
const GstRTPChannelOrder *res = NULL;
g_return_val_if_fail (pos != NULL, NULL);
for (i = 0; channel_orders[i].pos; i++) {
if (channel_orders[i].channels != channels)
continue;
if (check_channels (&channel_orders[i], pos)) {
res = &channel_orders[i];
break;
}
}
return res;
}
/**
* gst_rtp_channels_create_default:
* @channels: the amount of channels
* @order: a channel order
*
* Get the channel order info the @order and @channels.
*
* Returns: a #GstRTPChannelOrder with the channel information or NULL when
* @order is not a know layout for @channels.
*/
const GstRTPChannelOrder *
gst_rtp_channels_get_by_order (gint channels, const gchar * order)
{
gint i;
const GstRTPChannelOrder *res = NULL;
for (i = 0; channel_orders[i].pos; i++) {
if (channel_orders[i].channels != channels)
continue;
/* no name but channels match, continue */
if (!channel_orders[i].name || !order) {
res = &channel_orders[i];
break;
}
/* compare names */
if (g_ascii_strcasecmp (channel_orders[i].name, order)) {
res = &channel_orders[i];
break;
}
}
return res;
}
/**
* gst_rtp_channels_get_by_index:
* @channels: the amount of channels
* @idx: the channel index to retrieve
*
* Get the allowed channel order descriptions for @channels. @idx can be used to
* retrieve the desired index.
*
* Returns: a #GstRTPChannelOrder at @idx, NULL when there are no valid channel
* orders.
*/
const GstRTPChannelOrder *
gst_rtp_channels_get_by_index (gint channels, guint idx)
{
gint i;
const GstRTPChannelOrder *res = NULL;
for (i = 0; channel_orders[i].pos; i++) {
if (channel_orders[i].channels != channels)
continue;
if (idx == 0) {
res = &channel_orders[i];
break;
}
idx--;
}
return res;
}
/**
* gst_rtp_channels_create_default:
* @channels: the amount of channels
*
* Create a default none channel mapping for @channels.
*
* Returns: a #GstAudioChannelPosition with all the channel position info set to
* #GST_AUDIO_CHANNEL_POSITION_NONE.
*/
GstAudioChannelPosition *
gst_rtp_channels_create_default (gint channels)
{
gint i;
GstAudioChannelPosition *posn;
g_return_val_if_fail (channels > 0, NULL);
posn = g_new (GstAudioChannelPosition, channels);
for (i = 0; i < channels; i++)
posn[i] = GST_AUDIO_CHANNEL_POSITION_NONE;
return posn;
}
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