1 /* GStreamer
2 * Copyright (C) <2021> Collabora Ltd.
3 * Author: Nicolas Dufresne <nicolas.dufresne@collabora.com>
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Library General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Library General Public License for more details.
14 *
15 * You should have received a copy of the GNU Library General Public
16 * License along with this library; if not, write to the
17 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
18 * Boston, MA 02110-1301, USA.
19 */
20
21 /**
22 * SECTION:plugin-codecalpha
23 *
24 * This plugin contains a set of utilities that helps handling alpha encoded
25 * streams as produced by some WebM streams using VP8/VP9. The elements are
26 * meant to be used in decoder wrappers which allows playbin to automatically
27 * handle these streams.
28 *
29 * `codecalphademux` will produce two streams out of a stream of buffers holding
30 * the #GstVideoCodecAlphaMeta. The presence of the meta is indicated by the
31 * usage of the field `codec-alpha=(boolean)true` in the caps. This is only
32 * applicable to VP8 and VP9 for now.
33 *
34 * Wrappers for vp8dec and vp9dec are available, allowing seamless support for
35 * these streams inside playbin (which is used by WebKit GTK and WPE).
36 *
37 * Since: 1.20
38 */
39
40 #ifdef HAVE_CONFIG_H
41 # include <config.h>
42 #endif
43
44 #include <gst/gst.h>
45
46 #include "gstcodecalphademux.h"
47 #include "gstalphacombine.h"
48 #include "gstvp8alphadecodebin.h"
49 #include "gstvp9alphadecodebin.h"
50
51 /* When wrapping, use the original rank plus this offset. The ad-hoc rules is
52 * that hardware implementation will use PRIMARY+1 or +2 to override the
53 * software decoder, so the offset must be large enough to jump over those.
54 * This should also be small enough so that a marginal (64) or secondary
55 * wrapper does not cross the PRIMARY line.
56 */
57 #define RANK_OFFSET 10
58
59 static gboolean
plugin_init(GstPlugin * plugin)60 plugin_init (GstPlugin * plugin)
61 {
62 gboolean ret = FALSE;
63
64 ret |= GST_ELEMENT_REGISTER (codec_alpha_demux, plugin);
65 ret |= GST_ELEMENT_REGISTER (alpha_combine, plugin);
66 ret |= GST_ELEMENT_REGISTER (vp8_alpha_decode_bin, plugin);
67 ret |= GST_ELEMENT_REGISTER (vp9_alpha_decode_bin, plugin);
68
69 return ret;
70 }
71
72 GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
73 GST_VERSION_MINOR,
74 codecalpha,
75 "CODEC Alpha Utilities",
76 plugin_init, VERSION, "LGPL", GST_PACKAGE_NAME, GST_PACKAGE_ORIGIN)
77