audiodecoder: add API for setting caps on the source pad

This patch adds API in the audio decoder base class for setting the arbitrary
caps on the source pad.  Previously only caps converted from audio info were
possible.  This is particularly useful when subclass wants to set caps features
for audio decoder producing metadata.

docs/libs/gst-plugins-base-libs-sections.txt

@@ -393,6 +393,7 @@ GST_AUDIO_DECODER_STREAM_LOCK
 GST_AUDIO_DECODER_STREAM_UNLOCK
 gst_audio_decoder_finish_frame
 gst_audio_decoder_set_output_format
+gst_audio_decoder_set_output_caps
 gst_audio_decoder_negotiate
 gst_audio_decoder_allocate_output_buffer
 gst_audio_decoder_get_allocator

gst-libs/gst/audio/gstaudiodecoder.c

@@ -158,6 +158,7 @@ typedef struct _GstAudioDecoderContext
 
   /* (output) audio format */
   GstAudioInfo info;
+  GstCaps *caps;
   gboolean output_format_changed;
 
   /* parsing state */
@@ -513,6 +514,7 @@ gst_audio_decoder_reset (GstAudioDecoder * dec, gboolean full)
 
     GST_OBJECT_LOCK (dec);
     gst_caps_replace (&dec->priv->ctx.input_caps, NULL);
+    gst_caps_replace (&dec->priv->ctx.caps, NULL);
     gst_caps_replace (&dec->priv->ctx.allocation_caps, NULL);
 
     memset (&dec->priv->ctx, 0, sizeof (dec->priv->ctx));
@@ -625,10 +627,11 @@ gst_audio_decoder_negotiate_default (GstAudioDecoder * dec)
 
   g_return_val_if_fail (GST_IS_AUDIO_DECODER (dec), FALSE);
   g_return_val_if_fail (GST_AUDIO_INFO_IS_VALID (&dec->priv->ctx.info), FALSE);
+  g_return_val_if_fail (GST_IS_CAPS (dec->priv->ctx.caps), FALSE);
 
   klass = GST_AUDIO_DECODER_GET_CLASS (dec);
 
-  caps = gst_audio_info_to_caps (&dec->priv->ctx.info);
+  caps = dec->priv->ctx.caps;
   if (dec->priv->ctx.allocation_caps == NULL)
     dec->priv->ctx.allocation_caps = gst_caps_ref (caps);
 
@@ -697,7 +700,6 @@ done:
 
   if (query)
     gst_query_unref (query);
-  gst_caps_unref (caps);
 
   return res;
 
@@ -767,21 +769,58 @@ gst_audio_decoder_set_output_format (GstAudioDecoder * dec,
     const GstAudioInfo * info)
 {
   gboolean res = TRUE;
-  guint old_rate;
   GstCaps *caps = NULL;
-  GstCaps *templ_caps;
 
   g_return_val_if_fail (GST_IS_AUDIO_DECODER (dec), FALSE);
   g_return_val_if_fail (GST_AUDIO_INFO_IS_VALID (info), FALSE);
 
-  GST_DEBUG_OBJECT (dec, "Setting output format");
-
-  GST_AUDIO_DECODER_STREAM_LOCK (dec);
-
   /* If the audio info can't be converted to caps,
    * it was invalid */
   caps = gst_audio_info_to_caps (info);
-  if (!caps)
+  if (!caps) {
+    GST_WARNING_OBJECT (dec, "invalid output format");
+    return FALSE;
+  }
+
+  res = gst_audio_decoder_set_output_caps (dec, caps);
+  gst_caps_unref (caps);
+
+  return res;
+}
+
+/**
+ * gst_audio_decoder_set_output_caps:
+ * @dec: a #GstAudioDecoder
+ * @caps: (transfer none): (fixed) #GstCaps
+ *
+ * Configure output caps on the srcpad of @dec. Similar to
+ * gst_audio_decoder_set_output_format(), but allows subclasses to specify
+ * output caps that can't be expressed via #GstAudioInfo e.g. caps that have
+ * caps features.
+ *
+ * Returns: %TRUE on success.
+ *
+ * Since: 1.16
+ **/
+gboolean
+gst_audio_decoder_set_output_caps (GstAudioDecoder * dec, GstCaps * caps)
+{
+  gboolean res = TRUE;
+  guint old_rate;
+  GstCaps *templ_caps;
+  GstAudioInfo info;
+
+  g_return_val_if_fail (GST_IS_AUDIO_DECODER (dec), FALSE);
+
+  GST_DEBUG_OBJECT (dec, "Setting srcpad caps %" GST_PTR_FORMAT, caps);
+
+  GST_AUDIO_DECODER_STREAM_LOCK (dec);
+
+  if (!gst_caps_is_fixed (caps))
+    goto refuse_caps;
+
+  /* check if caps can be parsed */
+  if (!gst_audio_info_from_caps (&info, caps))
     goto refuse_caps;
 
   /* Only allow caps that are a subset of the template caps */
@@ -804,16 +843,15 @@ gst_audio_decoder_set_output_format (GstAudioDecoder * dec,
 
   /* copy the GstAudioInfo */
   GST_OBJECT_LOCK (dec);
-  dec->priv->ctx.info = *info;
+  dec->priv->ctx.info = info;
   GST_OBJECT_UNLOCK (dec);
+
+  gst_caps_replace (&dec->priv->ctx.caps, caps);
   dec->priv->ctx.output_format_changed = TRUE;
 
 done:
   GST_AUDIO_DECODER_STREAM_UNLOCK (dec);
 
-  if (caps)
-    gst_caps_unref (caps);
-
   return res;
 
   /* ERRORS */

gst-libs/gst/audio/gstaudiodecoder.h

@@ -322,6 +322,9 @@ gboolean          gst_audio_decoder_set_output_format  (GstAudioDecoder    * dec
                                                         const GstAudioInfo * info);
 
 GST_AUDIO_API
+gboolean          gst_audio_decoder_set_output_caps  (GstAudioDecoder * dec,
+                                                      GstCaps         * caps);
+GST_AUDIO_API
 GstCaps *         gst_audio_decoder_proxy_getcaps (GstAudioDecoder * decoder,
                                                    GstCaps         * caps,
                                                    GstCaps         * filter);