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Original commit message from CVS: * gst/rtp/gstrtpchannels.c: (gst_rtp_channels_get_by_index): * gst/rtp/gstrtpchannels.h: Add method to get possible channel positions.
167 lines
4.1 KiB
C
167 lines
4.1 KiB
C
/* GStreamer
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* Copyright (C) <2008> Wim Taymans <wim.taymans@gmail.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#include <string.h>
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#include <stdlib.h>
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#include "gstrtpchannels.h"
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/*
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* RTP channel positions as discussed in RFC 3551 and also RFC 3555
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*
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* We can't really represent the described channel positions in GStreamer but we
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* implement a (very rough) approximation here.
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*/
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static gboolean
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check_channels (const GstRTPChannelOrder * order,
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const GstAudioChannelPosition * pos)
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{
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gint i;
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gboolean res = TRUE;
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for (i = 0; i < order->channels; i++) {
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if (order->pos[i] != pos[i]) {
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res = FALSE;
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break;
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}
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}
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return res;
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}
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/**
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* gst_rtp_channels_get_by_pos:
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* @channels: the amount of channels
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* @pos: a channel layout
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*
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* Return a description of the channel layout.
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*
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* Returns: a #GstRTPChannelOrder with the channel information or NULL when @pos
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* is not a valid layout.
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*/
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const GstRTPChannelOrder *
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gst_rtp_channels_get_by_pos (gint channels, const GstAudioChannelPosition * pos)
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{
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gint i;
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const GstRTPChannelOrder *res = NULL;
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g_return_val_if_fail (pos != NULL, NULL);
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for (i = 0; channel_orders[i].pos; i++) {
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if (channel_orders[i].channels != channels)
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continue;
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if (check_channels (&channel_orders[i], pos)) {
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res = &channel_orders[i];
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break;
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}
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}
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return res;
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}
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/**
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* gst_rtp_channels_create_default:
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* @channels: the amount of channels
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* @order: a channel order
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*
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* Get the channel order info the @order and @channels.
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*
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* Returns: a #GstRTPChannelOrder with the channel information or NULL when
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* @order is not a know layout for @channels.
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*/
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const GstRTPChannelOrder *
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gst_rtp_channels_get_by_order (gint channels, const gchar * order)
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{
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gint i;
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const GstRTPChannelOrder *res = NULL;
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for (i = 0; channel_orders[i].pos; i++) {
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if (channel_orders[i].channels != channels)
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continue;
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/* no name but channels match, continue */
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if (!channel_orders[i].name || !order) {
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res = &channel_orders[i];
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break;
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}
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/* compare names */
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if (g_ascii_strcasecmp (channel_orders[i].name, order)) {
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res = &channel_orders[i];
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break;
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}
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}
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return res;
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}
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/**
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* gst_rtp_channels_get_by_index:
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* @channels: the amount of channels
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* @idx: the channel index to retrieve
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*
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* Get the allowed channel order descriptions for @channels. @idx can be used to
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* retrieve the desired index.
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*
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* Returns: a #GstRTPChannelOrder at @idx, NULL when there are no valid channel
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* orders.
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*/
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const GstRTPChannelOrder *
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gst_rtp_channels_get_by_index (gint channels, guint idx)
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{
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gint i;
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const GstRTPChannelOrder *res = NULL;
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for (i = 0; channel_orders[i].pos; i++) {
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if (channel_orders[i].channels != channels)
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continue;
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if (idx == 0) {
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res = &channel_orders[i];
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break;
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}
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idx--;
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}
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return res;
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}
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/**
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* gst_rtp_channels_create_default:
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* @channels: the amount of channels
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*
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* Create a default none channel mapping for @channels.
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*
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* Returns: a #GstAudioChannelPosition with all the channel position info set to
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* #GST_AUDIO_CHANNEL_POSITION_NONE.
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*/
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GstAudioChannelPosition *
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gst_rtp_channels_create_default (gint channels)
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{
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gint i;
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GstAudioChannelPosition *posn;
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g_return_val_if_fail (channels > 0, NULL);
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posn = g_new (GstAudioChannelPosition, channels);
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for (i = 0; i < channels; i++)
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posn[i] = GST_AUDIO_CHANNEL_POSITION_NONE;
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return posn;
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}
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