gst/rtp/: Add mappings for multichannel support. Does not completely just work because the getcaps function does not ...

Original commit message from CVS:
* gst/rtp/gstrtpL16depay.c: (gst_rtp_L16_depay_setcaps):
* gst/rtp/gstrtpL16pay.c: (gst_rtp_L16_pay_setcaps),
(gst_rtp_L16_pay_getcaps):
* gst/rtp/gstrtpchannels.c: (check_channels),
(gst_rtp_channels_get_by_pos), (gst_rtp_channels_get_by_order),
(gst_rtp_channels_create_default):
* gst/rtp/gstrtpchannels.h:
Add mappings for multichannel support. Does not completely just work
because the getcaps function does not yet return the allowed channel
mappings. See #556641.

1 files changed, 136 insertions, 0 deletions

diff --git a/gst/rtp/gstrtpchannels.c b/gst/rtp/gstrtpchannels.c
new file mode 100644
index 00000000..05100f0f
--- /dev/null
+++ b/gst/rtp/gstrtpchannels.c
@@ -0,0 +1,136 @@
+/* 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_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;
+}