From a74dcb7dc00f053c175d2b296494d648c9fb60bd Mon Sep 17 00:00:00 2001
From: Stefano Sabatini <stefasab@gmail.com>
Date: Sun, 29 Jul 2012 16:35:43 +0200
Subject: lavfi/color: cache and reuse colored picture in context

Avoid to fill the same picture again and again with the same content.

Optimize computation, and provides an example for the use of the
AV_PERM_REUSE permission flag.
---
 libavfilter/vsrc_color.c | 34 ++++++++++++++++++++++------------
 1 file changed, 22 insertions(+), 12 deletions(-)

(limited to 'libavfilter')

diff --git a/libavfilter/vsrc_color.c b/libavfilter/vsrc_color.c
index ca336ace6e..efbaee4115 100644
--- a/libavfilter/vsrc_color.c
+++ b/libavfilter/vsrc_color.c
@@ -45,6 +45,7 @@ typedef struct {
     uint64_t pts;
     FFDrawContext draw;
     FFDrawColor color;
+    AVFilterBufferRef *picref;  ///< cached reference containing the painted picture
 } ColorContext;
 
 #define OFFSET(x) offsetof(ColorContext, x)
@@ -92,6 +93,12 @@ end:
     return ret;
 }
 
+static av_cold void color_uninit(AVFilterContext *ctx)
+{
+    ColorContext *color = ctx->priv;
+    avfilter_unref_bufferp(&color->picref);
+}
+
 static int query_formats(AVFilterContext *ctx)
 {
     ff_set_common_formats(ctx, ff_draw_supported_pixel_formats(0));
@@ -124,18 +131,24 @@ static int color_config_props(AVFilterLink *inlink)
 static int color_request_frame(AVFilterLink *link)
 {
     ColorContext *color = link->src->priv;
-    AVFilterBufferRef *picref = ff_get_video_buffer(link, AV_PERM_WRITE, color->w, color->h);
     AVFilterBufferRef *buf_out;
     int ret;
 
-    if (!picref)
-        return AVERROR(ENOMEM);
-
-    picref->video->sample_aspect_ratio = (AVRational) {1, 1};
-    picref->pts = color->pts++;
-    picref->pos = -1;
+    if (!color->picref) {
+        color->picref =
+            ff_get_video_buffer(link, AV_PERM_WRITE|AV_PERM_PRESERVE|AV_PERM_REUSE,
+                                color->w, color->h);
+        if (!color->picref)
+            return AVERROR(ENOMEM);
+        ff_fill_rectangle(&color->draw, &color->color,
+                          color->picref->data, color->picref->linesize,
+                          0, 0, color->w, color->h);
+        color->picref->video->sample_aspect_ratio = (AVRational) {1, 1};
+        color->picref->pos = -1;
+    }
 
-    buf_out = avfilter_ref_buffer(picref, ~0);
+    color->picref->pts = color->pts++;
+    buf_out = avfilter_ref_buffer(color->picref, ~AV_PERM_WRITE);
     if (!buf_out) {
         ret = AVERROR(ENOMEM);
         goto fail;
@@ -145,8 +158,6 @@ static int color_request_frame(AVFilterLink *link)
     if (ret < 0)
         goto fail;
 
-    ff_fill_rectangle(&color->draw, &color->color, picref->data, picref->linesize,
-                      0, 0, color->w, color->h);
     ret = ff_draw_slice(link, 0, color->h, 1);
     if (ret < 0)
         goto fail;
@@ -154,8 +165,6 @@ static int color_request_frame(AVFilterLink *link)
     ret = ff_end_frame(link);
 
 fail:
-    avfilter_unref_buffer(picref);
-
     return ret;
 }
 
@@ -165,6 +174,7 @@ AVFilter avfilter_vsrc_color = {
 
     .priv_size = sizeof(ColorContext),
     .init      = color_init,
+    .uninit    = color_uninit,
 
     .query_formats = query_formats,
 
-- 
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