matroskademux: Store alpha stream in VideoCodecAlphaMeta

This generalize the feature over using mini object quark data. If
that feature was Matroska specifc, using the new CustomMeta would have
been enough and arguably cleaner then QData, though it seems that
similar technique is use with AV1 Image Format (AVIF).

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-good/-/merge_requests/968>

diff --git a/gst/matroska/matroska-demux.c b/gst/matroska/matroska-demux.c
index 05266a1..a1e5d1c 100644 (file)
--- a/gst/matroska/matroska-demux.c
+++ b/gst/matroska/matroska-demux.c
@@ -64,6 +64,7 @@
 #include <gst/audio/audio.h>
 #include <gst/tag/tag.h>
 #include <gst/pbutils/pbutils.h>
+#include <gst/video/gstvideocodecalphameta.h>
 #include <gst/video/video.h>
 
 #include "gstmatroskaelements.h"
@@ -4982,14 +4983,20 @@ gst_matroska_demux_parse_blockgroup_or_simpleblock (GstMatroskaDemux * demux,
 
         while ((blockadd = g_queue_pop_head (&additions))) {
           if (blockadd->id == 1
-              && !strcmp (stream->codec_id, GST_MATROSKA_CODEC_ID_VIDEO_VP8)) {
-            GST_TRACE_OBJECT (demux, "adding block addition %u as VP8 alpha "
-                "qdata to buffer %p, %u bytes", (guint) blockadd->id, buf,
+              && (!strcmp (stream->codec_id, GST_MATROSKA_CODEC_ID_VIDEO_VP8)
+                  || !strcmp (stream->codec_id,
+                      GST_MATROSKA_CODEC_ID_VIDEO_VP9))) {
+            GstBuffer *alpha_buffer;
+
+            GST_TRACE_OBJECT (demux, "adding block addition %u as VP8/VP9 "
+                "alpha meta to buffer %p, %u bytes", (guint) blockadd->id, buf,
                 (guint) blockadd->size);
-            gst_mini_object_set_qdata (GST_MINI_OBJECT (sub),
-                matroska_block_additional_quark,
-                g_bytes_new_take (blockadd->data, blockadd->size),
-                (GDestroyNotify) g_bytes_unref);
+
+            alpha_buffer = gst_buffer_new_wrapped (blockadd->data,
+                blockadd->size);
+            gst_buffer_copy_into (alpha_buffer, sub,
+                GST_BUFFER_COPY_FLAGS | GST_BUFFER_COPY_TIMESTAMPS, 0, -1);
+            gst_buffer_add_video_codec_alpha_meta (sub, alpha_buffer);
           } else {
             g_free (blockadd->data);
           }