apev2mux: write APE tags at end for wavpack files

http://www.wavpack.com/file_format.txt:
"Both the APEv2 tags and/or ID3v1 tags must come at the end of the
WavPack file, with the ID3v1 coming last if both are present."

WavPack files that contain APEv2 tags at the beginning of the files
are unplayable on players that use FFmpeg (like VLC) and most other
software (except Banshee). Players that use libwavpack directly can
play the files because it skips the tags, but does not recognize the
tag data at that location.

https://bugzilla.gnome.org/show_bug.cgi?id=711437

1 files changed, 37 insertions, 2 deletions

diff --git a/ext/taglib/gstapev2mux.cc b/ext/taglib/gstapev2mux.cc
index eb46f823e..e69de7e25 100644
--- a/ext/taglib/gstapev2mux.cc
+++ b/ext/taglib/gstapev2mux.cc
@@ -71,7 +71,7 @@ static GstStaticPadTemplate sink_template = GST_STATIC_PAD_TEMPLATE ("sink",
 
 G_DEFINE_TYPE (GstApev2Mux, gst_apev2_mux, GST_TYPE_TAG_MUX);
 
-static GstBuffer *gst_apev2_mux_render_tag (GstTagMux * mux,
+static GstBuffer *gst_apev2_mux_render_start_tag (GstTagMux * mux,
     const GstTagList * taglist);
 static GstBuffer *gst_apev2_mux_render_end_tag (GstTagMux * mux,
     const GstTagList * taglist);
@@ -82,7 +82,7 @@ gst_apev2_mux_class_init (GstApev2MuxClass * klass)
   GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
 
   GST_TAG_MUX_CLASS (klass)->render_start_tag =
-      GST_DEBUG_FUNCPTR (gst_apev2_mux_render_tag);
+      GST_DEBUG_FUNCPTR (gst_apev2_mux_render_start_tag);
   GST_TAG_MUX_CLASS (klass)->render_end_tag =
       GST_DEBUG_FUNCPTR (gst_apev2_mux_render_end_tag);
 
@@ -106,6 +106,29 @@ gst_apev2_mux_init (GstApev2Mux * apev2mux)
   /* nothing to do */
 }
 
+static gboolean
+gst_apev2_mux_have_wavpack (GstApev2Mux * apev2mux)
+{
+  const GstStructure *s;
+  gboolean ret;
+  GstCaps *caps;
+  GstPad *sink;
+
+  sink = gst_element_get_static_pad (GST_ELEMENT_CAST (apev2mux), "sink");
+  caps = gst_pad_get_current_caps (sink);
+  gst_object_unref (sink);
+
+  if (caps == NULL)
+    return FALSE;
+
+  s = gst_caps_get_structure (caps, 0);
+  ret = gst_structure_has_name (s, "audio/x-wavpack");
+  gst_caps_unref (caps);
+
+  GST_LOG_OBJECT (apev2mux, "got wavpack input: %s", ret ? "yes" : "no");
+  return ret;
+}
+
 static void
 add_one_tag (const GstTagList * list, const gchar * tag, gpointer user_data)
 {
@@ -369,7 +392,19 @@ gst_apev2_mux_render_tag (GstTagMux * mux, const GstTagList * taglist)
 }
 
 static GstBuffer *
+gst_apev2_mux_render_start_tag (GstTagMux * mux, const GstTagList * taglist)
+{
+  if (gst_apev2_mux_have_wavpack (GST_APEV2_MUX (mux)))
+    return NULL;
+
+  return gst_apev2_mux_render_tag (mux, taglist);
+}
+
+static GstBuffer *
 gst_apev2_mux_render_end_tag (GstTagMux * mux, const GstTagList * taglist)
 {
+  if (gst_apev2_mux_have_wavpack (GST_APEV2_MUX (mux)))
+    return gst_apev2_mux_render_tag (mux, taglist);
+
   return NULL;
 }