From 2cd927435cb03a64b3243215fff54d3c2e448917 Mon Sep 17 00:00:00 2001 From: Nicolas Dufresne Date: Fri, 2 Apr 2021 15:07:22 -0400 Subject: [PATCH] codecalpha: Implement alphacombine element This element will merge video buffers in order to use the alpha stream luma plane as the alpha of the video stream. The implementation is zero-copy and currently only support merging I420 stream with an I420, NV12 or GRAY8 alpha stream. Part-of: --- gst/codecalpha/gstalphacombine.c | 599 +++++++++++++++++++++++++++++++++++++++ gst/codecalpha/gstalphacombine.h | 35 +++ gst/codecalpha/gstplugin.c | 2 + gst/codecalpha/meson.build | 1 + 4 files changed, 637 insertions(+) create mode 100644 gst/codecalpha/gstalphacombine.c create mode 100644 gst/codecalpha/gstalphacombine.h diff --git a/gst/codecalpha/gstalphacombine.c b/gst/codecalpha/gstalphacombine.c new file mode 100644 index 0000000..8d417b2 --- /dev/null +++ b/gst/codecalpha/gstalphacombine.c @@ -0,0 +1,599 @@ +/* GStreamer + * Copyright (C) <2021> Collabora Ltd. + * Author: Nicolas Dufresne + * + * 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., 51 Franklin St, Fifth Floor, + * Boston, MA 02110-1301, USA. + */ + +/** + * SECTION:element-alphacombine + * @title: Alpha Combiner + * + * This element can combine a Luma plane from one stream as being the alpha + * plane of another stream. This element can only work with planar formats + * that have an equivalent format with an alpha plane. This is notably used to + * combine VP8/VP9 alpha streams from WebM container. + * + * ## Example launch line + * |[ + * gst-launch-1.0 -v videotestsrc ! .c videotestsrc pattern=ball ! .c + * alphacombine name=c ! compositor ! autovideosink + * ]| This pipeline uses luma of a ball test pattern as alpha, combined with + * default test pattern and renders the resulting moving ball on a checker + * board. + * + * Since: 1.20 + */ + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include + +#include "gstalphacombine.h" + + +#define SUPPORTED_SINK_FORMATS "{ I420 }" +#define SUPPORTED_ALPHA_FORMATS "{ GRAY8, I420, NV12 }" +#define SUPPORTED_SRC_FORMATS "{ A420 }" + +/* *INDENT-OFF* */ +struct { + GstVideoFormat sink; + GstVideoFormat alpha; + GstVideoFormat src; +} format_map[] = { + { + .sink = GST_VIDEO_FORMAT_I420, + .alpha = GST_VIDEO_FORMAT_I420, + .src = GST_VIDEO_FORMAT_A420 + },{ + .sink = GST_VIDEO_FORMAT_I420, + .alpha = GST_VIDEO_FORMAT_GRAY8, + .src = GST_VIDEO_FORMAT_A420 + },{ + .sink = GST_VIDEO_FORMAT_I420, + .alpha = GST_VIDEO_FORMAT_NV12, + .src = GST_VIDEO_FORMAT_A420 + } +}; +/* *INDENT-ON* */ + +GST_DEBUG_CATEGORY_STATIC (alphacombine_debug); +#define GST_CAT_DEFAULT (alphacombine_debug) + +struct _GstAlphaCombine +{ + GstElement parent; + + GstPad *sink_pad; + GstPad *alpha_pad; + GstPad *src_pad; + + /* protected by sink_pad stream lock */ + GstBuffer *last_alpha_buffer; + + GMutex buffer_lock; + GCond buffer_cond; + GstBuffer *alpha_buffer; + /* Ref-counted flushing state */ + guint flushing; + + GstVideoInfo sink_vinfo; + GstVideoInfo alpha_vinfo; + GstVideoFormat src_format; + + gboolean alpha_is_eos; +}; + +#define gst_alpha_combine_parent_class parent_class +G_DEFINE_TYPE_WITH_CODE (GstAlphaCombine, gst_alpha_combine, + GST_TYPE_ELEMENT, + GST_DEBUG_CATEGORY_INIT (alphacombine_debug, "alphacombine", 0, + "Alpha Combiner")); + +GST_ELEMENT_REGISTER_DEFINE (alpha_combine, "alphacombine", + GST_RANK_NONE, GST_TYPE_ALPHA_COMBINE); + +static GstStaticPadTemplate gst_alpha_combine_sink_template = +GST_STATIC_PAD_TEMPLATE ("sink", + GST_PAD_SINK, + GST_PAD_ALWAYS, + GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE (SUPPORTED_SINK_FORMATS)) + ); + +static GstStaticPadTemplate gst_alpha_combine_alpha_template = +GST_STATIC_PAD_TEMPLATE ("alpha", + GST_PAD_SINK, + GST_PAD_ALWAYS, + GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE (SUPPORTED_ALPHA_FORMATS)) + ); + +static GstStaticPadTemplate gst_alpha_combine_src_template = +GST_STATIC_PAD_TEMPLATE ("src", + GST_PAD_SRC, + GST_PAD_ALWAYS, + GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE (SUPPORTED_SRC_FORMATS)) + ); + +static void +gst_alpha_combine_unlock (GstAlphaCombine * self) +{ + g_mutex_lock (&self->buffer_lock); + self->flushing++; + g_cond_broadcast (&self->buffer_cond); + g_mutex_unlock (&self->buffer_lock); +} + +static void +gst_alpha_combine_unlock_stop (GstAlphaCombine * self) +{ + g_mutex_lock (&self->buffer_lock); + g_assert (self->flushing); + self->flushing--; + g_mutex_unlock (&self->buffer_lock); +} + +static void +gst_alpha_combine_reset (GstAlphaCombine * self) +{ + gst_buffer_replace (&self->alpha_buffer, NULL); + gst_buffer_replace (&self->last_alpha_buffer, NULL); + self->alpha_is_eos = FALSE; +} + +/* + * gst_alpha_combine_negotiate: + * @self: #GstAlphaCombine pointer + * + * Verify that the stream and alpha stream format are compatible and fail + * otherwise. There is no effort in helping upstream to dynamically negotiate + * a valid combination to keep the complexity low, and because this would be a + * very atypical usage. + */ +static gboolean +gst_alpha_combine_negotiate (GstAlphaCombine * self) +{ + gint i; + GstVideoFormat src_format = GST_VIDEO_FORMAT_UNKNOWN; + GstVideoFormat sink_format = GST_VIDEO_INFO_FORMAT (&self->sink_vinfo); + GstVideoFormat alpha_format = GST_VIDEO_INFO_FORMAT (&self->alpha_vinfo); + + if (self->src_format != GST_VIDEO_FORMAT_UNKNOWN) + return TRUE; + + for (i = 0; i < G_N_ELEMENTS (format_map); i++) { + if (format_map[i].sink == sink_format + && format_map[i].alpha == alpha_format) { + src_format = format_map[i].src; + break; + } + } + + if (src_format == GST_VIDEO_FORMAT_UNKNOWN) { + GST_ELEMENT_ERROR (self, STREAM, FORMAT, ("Unsupported formats."), + ("Cannot combined '%s' and '%s' into any supported transparent format", + gst_video_format_to_string (sink_format), + gst_video_format_to_string (alpha_format))); + return FALSE; + } + + if (GST_VIDEO_INFO_COLORIMETRY (&self->sink_vinfo).range != + GST_VIDEO_INFO_COLORIMETRY (&self->alpha_vinfo).range) { + GST_ELEMENT_ERROR (self, STREAM, FORMAT, ("Color range miss-match"), + ("We can only combine buffers if they have the same color range.")); + return FALSE; + } + + self->src_format = src_format; + return TRUE; +} + +static GstFlowReturn +gst_alpha_combine_pull_alpha_buffer (GstAlphaCombine * self, + GstBuffer ** alpha_buffer) +{ + g_mutex_lock (&self->buffer_lock); + + while (!self->alpha_buffer && !self->flushing) + g_cond_wait (&self->buffer_cond, &self->buffer_lock); + + if (self->flushing) { + g_mutex_unlock (&self->buffer_lock); + return GST_FLOW_FLUSHING; + } + + /* Now is a good time to validate the formats, as the alpha_vinfo won't be + * updated until we signal this alpha_buffer_as being consumed */ + if (!gst_alpha_combine_negotiate (self)) { + g_mutex_unlock (&self->buffer_lock); + return GST_FLOW_NOT_NEGOTIATED; + } + + *alpha_buffer = self->alpha_buffer; + self->alpha_buffer = NULL; + + g_cond_broadcast (&self->buffer_cond); + g_mutex_unlock (&self->buffer_lock); + + if (GST_BUFFER_FLAG_IS_SET (*alpha_buffer, GST_BUFFER_FLAG_GAP)) { + if (!self->last_alpha_buffer) { + GST_ELEMENT_ERROR (self, STREAM, WRONG_TYPE, + ("Cannot handle streams without an initial alpha buffer."), (NULL)); + gst_buffer_replace (alpha_buffer, NULL); + return GST_FLOW_ERROR; + } + + /* Re-use the last alpha buffer if one is gone missing */ + gst_buffer_replace (alpha_buffer, self->last_alpha_buffer); + } + + return GST_FLOW_OK; +} + +static GstFlowReturn +gst_alpha_combine_push_alpha_buffer (GstAlphaCombine * self, GstBuffer * buffer) +{ + g_mutex_lock (&self->buffer_lock); + + /* We wait for the alpha_buffer to be consumed and store the buffer for the + * sink_chain to pick it up */ + while (self->alpha_buffer && !self->flushing) + g_cond_wait (&self->buffer_cond, &self->buffer_lock); + + if (self->flushing) { + gst_buffer_unref (buffer); + g_mutex_unlock (&self->buffer_lock); + return GST_FLOW_FLUSHING; + } + + self->alpha_buffer = buffer; + GST_DEBUG_OBJECT (self, "Stored pending alpha buffer %p", buffer); + g_cond_signal (&self->buffer_cond); + g_mutex_unlock (&self->buffer_lock); + + return GST_FLOW_OK; +} + +static GstFlowReturn +gst_alpha_combine_sink_chain (GstPad * pad, GstObject * object, + GstBuffer * src_buffer) +{ + GstAlphaCombine *self = GST_ALPHA_COMBINE (object); + GstFlowReturn ret; + GstVideoMeta *vmeta; + GstBuffer *alpha_buffer; + GstMemory *alpha_mem = NULL; + gsize alpha_skip = 0; + gint alpha_stride; + GstBuffer *buffer; + + ret = gst_alpha_combine_pull_alpha_buffer (self, &alpha_buffer); + if (ret != GST_FLOW_OK) + return ret; + + GST_DEBUG_OBJECT (self, "Combining buffer %p with alpha buffer %p", + src_buffer, alpha_buffer); + + vmeta = gst_buffer_get_video_meta (alpha_buffer); + if (vmeta) { + guint idx, length; + if (gst_buffer_find_memory (alpha_buffer, vmeta->offset[GST_VIDEO_COMP_Y], + 1, &idx, &length, &alpha_skip)) { + alpha_mem = gst_buffer_get_memory (alpha_buffer, idx); + } + + alpha_stride = vmeta->stride[GST_VIDEO_COMP_Y]; + } else { + alpha_mem = gst_buffer_get_memory (alpha_buffer, 0); + alpha_stride = self->alpha_vinfo.stride[GST_VIDEO_COMP_Y]; + } + + if (!alpha_mem) { + gst_buffer_unref (alpha_buffer); + gst_buffer_unref (src_buffer); + GST_ELEMENT_ERROR (self, STREAM, WRONG_TYPE, + ("Invalid alpha video frame."), ("Could not find the plane")); + return GST_FLOW_ERROR; + } + + /* FIXME use some GstBuffer cache to reduce run-time allocation */ + buffer = gst_buffer_copy (src_buffer); + vmeta = gst_buffer_get_video_meta (buffer); + if (!vmeta) + vmeta = gst_buffer_add_video_meta (buffer, 0, + GST_VIDEO_INFO_FORMAT (&self->sink_vinfo), + GST_VIDEO_INFO_WIDTH (&self->sink_vinfo), + GST_VIDEO_INFO_HEIGHT (&self->sink_vinfo)); + + alpha_skip += gst_buffer_get_size (buffer); + gst_buffer_append_memory (buffer, alpha_mem); + vmeta->offset[GST_VIDEO_COMP_A] = alpha_skip; + vmeta->stride[GST_VIDEO_COMP_A] = alpha_stride; + vmeta->format = GST_VIDEO_FORMAT_A420; + vmeta->n_planes = 4; + + /* Keep the origina GstBuffer alive to make this buffer pool friendly */ + gst_buffer_add_parent_buffer_meta (buffer, src_buffer); + gst_buffer_add_parent_buffer_meta (buffer, alpha_buffer); + + gst_buffer_replace (&self->last_alpha_buffer, alpha_buffer); + gst_buffer_unref (src_buffer); + gst_buffer_unref (alpha_buffer); + + return gst_pad_push (self->src_pad, buffer); +} + +static GstFlowReturn +gst_alpha_combine_alpha_chain (GstPad * pad, GstObject * object, + GstBuffer * buffer) +{ + GstAlphaCombine *self = GST_ALPHA_COMBINE (object); + + if (self->alpha_is_eos) { + gst_buffer_unref (buffer); + return GST_FLOW_EOS; + } + + return gst_alpha_combine_push_alpha_buffer (self, buffer); +} + +static gboolean +gst_alpha_combine_set_sink_format (GstAlphaCombine * self, GstCaps * caps) +{ + GstEvent *event; + + if (!gst_video_info_from_caps (&self->sink_vinfo, caps)) { + GST_ELEMENT_ERROR (self, STREAM, FORMAT, ("Invalid video format"), (NULL)); + return FALSE; + } + + caps = gst_caps_copy (caps); + + gst_caps_set_simple (caps, "format", G_TYPE_STRING, "A420", NULL); + event = gst_event_new_caps (caps); + gst_caps_unref (caps); + + return gst_pad_push_event (self->src_pad, event); +} + +static gboolean +gst_alpha_combine_set_alpha_format (GstAlphaCombine * self, GstCaps * caps) +{ + /* We wait for the alpha_buffer to be consumed, so that we don't pick the + * caps too soon */ + g_mutex_lock (&self->buffer_lock); + + /* We wait for the alpha_buffer to be consumed and store the buffer for the + * sink_chain to pick it up */ + while (self->alpha_buffer && !self->flushing) + g_cond_wait (&self->buffer_cond, &self->buffer_lock); + + if (self->flushing) { + g_mutex_unlock (&self->buffer_lock); + return GST_FLOW_FLUSHING; + } + + if (!gst_video_info_from_caps (&self->alpha_vinfo, caps)) { + g_mutex_unlock (&self->buffer_lock); + GST_ELEMENT_ERROR (self, STREAM, FORMAT, ("Invalid video format"), (NULL)); + return FALSE; + } + + g_mutex_unlock (&self->buffer_lock); + + return TRUE; +} + +static gboolean +gst_alpha_combine_sink_event (GstPad * pad, GstObject * object, + GstEvent * event) +{ + GstAlphaCombine *self = GST_ALPHA_COMBINE (object); + + switch (event->type) { + case GST_EVENT_FLUSH_START: + gst_alpha_combine_unlock (self); + break; + case GST_EVENT_FLUSH_STOP: + gst_alpha_combine_unlock_stop (self); + break; + case GST_EVENT_CAPS: + { + GstCaps *caps; + gboolean ret; + + gst_event_parse_caps (event, &caps); + ret = gst_alpha_combine_set_sink_format (self, caps); + gst_event_unref (event); + + return ret; + } + default: + break; + } + + return gst_pad_event_default (pad, object, event); +} + +static gboolean +gst_alpha_combine_alpha_event (GstPad * pad, GstObject * object, + GstEvent * event) +{ + GstAlphaCombine *self = GST_ALPHA_COMBINE (object); + + switch (event->type) { + case GST_EVENT_FLUSH_START: + gst_alpha_combine_unlock (self); + break; + case GST_EVENT_FLUSH_STOP: + gst_alpha_combine_unlock_stop (self); + gst_alpha_combine_reset (self); + break; + case GST_EVENT_CAPS: + { + GstCaps *caps; + gboolean ret; + + gst_event_parse_caps (event, &caps); + ret = gst_alpha_combine_set_alpha_format (self, caps); + gst_event_unref (event); + + return ret; + } + case GST_EVENT_SEGMENT: + /* Passthrough the segment from the main stream and ignore this one */ + gst_event_unref (event); + return TRUE; + case GST_EVENT_EOS: + gst_event_unref (event); + self->alpha_is_eos = TRUE; + return TRUE; + default: + break; + } + + return gst_pad_event_default (pad, object, event); +} + +static gboolean +gst_alpha_combine_sink_query (GstPad * pad, GstObject * object, + GstQuery * query) +{ + switch (query->type) { + case GST_QUERY_ALLOCATION: + { + gst_query_add_allocation_meta (query, GST_VIDEO_META_API_TYPE, NULL); + return TRUE; + break; + } + default: + break; + } + + return gst_pad_query_default (pad, object, query); +} + +static GstStateChangeReturn +gst_alpha_combine_change_state (GstElement * element, GstStateChange transition) +{ + GstAlphaCombine *self = GST_ALPHA_COMBINE (element); + GstStateChangeReturn ret; + + switch (transition) { + case GST_STATE_CHANGE_READY_TO_PAUSED: + gst_alpha_combine_unlock_stop (self); + break; + case GST_STATE_CHANGE_PAUSED_TO_READY: + gst_alpha_combine_unlock (self); + break; + default: + break; + } + + ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition); + + switch (transition) { + case GST_STATE_CHANGE_PAUSED_TO_READY: + gst_alpha_combine_reset (self); + self->src_format = GST_VIDEO_FORMAT_UNKNOWN; + gst_video_info_init (&self->sink_vinfo); + gst_video_info_init (&self->alpha_vinfo); + break; + default: + break; + } + + return ret; +} + +static void +gst_alpha_combine_dispose (GObject * object) +{ + GstAlphaCombine *self = GST_ALPHA_COMBINE (object); + + g_clear_object (&self->sink_pad); + g_clear_object (&self->alpha_pad); + g_clear_object (&self->src_pad); + + G_OBJECT_CLASS (parent_class)->dispose (object); +} + +static void +gst_alpha_combine_finalize (GObject * object) +{ + GstAlphaCombine *self = GST_ALPHA_COMBINE (object); + + g_mutex_clear (&self->buffer_lock); + g_cond_clear (&self->buffer_cond); + + G_OBJECT_CLASS (parent_class)->finalize (object); +} + +static void +gst_alpha_combine_class_init (GstAlphaCombineClass * klass) +{ + GstElementClass *element_class = (GstElementClass *) klass; + GObjectClass *object_class = (GObjectClass *) klass; + + gst_element_class_set_static_metadata (element_class, + "Alpha Combiner", "Codec/Demuxer", + "Use luma from an opaque stream as alpha plane on another", + "Nicolas Dufresne "); + + gst_element_class_add_static_pad_template (element_class, + &gst_alpha_combine_sink_template); + gst_element_class_add_static_pad_template (element_class, + &gst_alpha_combine_alpha_template); + gst_element_class_add_static_pad_template (element_class, + &gst_alpha_combine_src_template); + + element_class->change_state = + GST_DEBUG_FUNCPTR (gst_alpha_combine_change_state); + + object_class->dispose = GST_DEBUG_FUNCPTR (gst_alpha_combine_dispose); + object_class->finalize = GST_DEBUG_FUNCPTR (gst_alpha_combine_finalize); +} + +static void +gst_alpha_combine_init (GstAlphaCombine * self) +{ + gst_element_create_all_pads (GST_ELEMENT (self)); + self->sink_pad = gst_element_get_static_pad (GST_ELEMENT (self), "sink"); + self->alpha_pad = gst_element_get_static_pad (GST_ELEMENT (self), "alpha"); + self->src_pad = gst_element_get_static_pad (GST_ELEMENT (self), "src"); + self->flushing = 1; + + g_mutex_init (&self->buffer_lock); + g_cond_init (&self->buffer_cond); + + GST_PAD_SET_PROXY_SCHEDULING (self->sink_pad); + GST_PAD_SET_PROXY_SCHEDULING (self->alpha_pad); + GST_PAD_SET_PROXY_SCHEDULING (self->src_pad); + + GST_PAD_SET_PROXY_ALLOCATION (self->sink_pad); + GST_PAD_SET_PROXY_ALLOCATION (self->alpha_pad); + + gst_pad_set_chain_function (self->sink_pad, gst_alpha_combine_sink_chain); + gst_pad_set_chain_function (self->alpha_pad, gst_alpha_combine_alpha_chain); + + gst_pad_set_event_function (self->sink_pad, gst_alpha_combine_sink_event); + gst_pad_set_event_function (self->alpha_pad, gst_alpha_combine_alpha_event); + + gst_pad_set_query_function (self->sink_pad, gst_alpha_combine_sink_query); + gst_pad_set_query_function (self->alpha_pad, gst_alpha_combine_sink_query); +} diff --git a/gst/codecalpha/gstalphacombine.h b/gst/codecalpha/gstalphacombine.h new file mode 100644 index 0000000..4237178 --- /dev/null +++ b/gst/codecalpha/gstalphacombine.h @@ -0,0 +1,35 @@ +/* GStreamer + * Copyright (C) <2021> Collabora Ltd. + * Author: Nicolas Dufresne + * + * 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., 51 Franklin St, Fifth Floor, + * Boston, MA 02110-1301, USA. + */ + +#ifndef __GST_ALPHA_COMBINE_H__ +#define __GST_ALPHA_COMBINE_H__ + +#include + +G_BEGIN_DECLS + +#define GST_TYPE_ALPHA_COMBINE (gst_alpha_combine_get_type()) +G_DECLARE_FINAL_TYPE (GstAlphaCombine, + gst_alpha_combine, GST, ALPHA_COMBINE, GstElement); + +GST_ELEMENT_REGISTER_DECLARE (alpha_combine); + +G_END_DECLS +#endif diff --git a/gst/codecalpha/gstplugin.c b/gst/codecalpha/gstplugin.c index 3a92c6a..f886932 100644 --- a/gst/codecalpha/gstplugin.c +++ b/gst/codecalpha/gstplugin.c @@ -25,6 +25,7 @@ #include #include "gstcodecalphademux.h" +#include "gstalphacombine.h" static gboolean plugin_init (GstPlugin * plugin) @@ -32,6 +33,7 @@ plugin_init (GstPlugin * plugin) gboolean ret = FALSE; ret |= GST_ELEMENT_REGISTER (codec_alpha_demux, plugin); + ret |= GST_ELEMENT_REGISTER (alpha_combine, plugin); return ret; } diff --git a/gst/codecalpha/meson.build b/gst/codecalpha/meson.build index 1c9d3b3..9638f3b 100644 --- a/gst/codecalpha/meson.build +++ b/gst/codecalpha/meson.build @@ -1,5 +1,6 @@ codecalpha_sources = [ 'gstplugin.c', + 'gstalphacombine.c', 'gstcodecalphademux.c', ] -- 2.7.4