From c38ae71f54f93c662c7f5ae950cc754d5d9edbf4 Mon Sep 17 00:00:00 2001
From: Stefano Sabatini <stefano.sabatini-lala@poste.it>
Date: Thu, 22 Oct 2009 22:00:33 +0000
Subject: [PATCH] Add video vertical flip filter.

Originally committed as revision 20352 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 doc/libavfilter.texi     |   8 +++
 libavfilter/Makefile     |   1 +
 libavfilter/allfilters.c |   1 +
 libavfilter/vf_vflip.c   | 102 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 112 insertions(+)
 create mode 100644 libavfilter/vf_vflip.c

diff --git a/doc/libavfilter.texi b/doc/libavfilter.texi
index db21d7fdf2..b612d1e616 100644
--- a/doc/libavfilter.texi
+++ b/doc/libavfilter.texi
@@ -115,4 +115,12 @@ The default value of ``w'' and ``h'' is 0.
 
 Pass the source unchanged to the output.
 
+@section vflip
+
+Flip the input video vertically.
+
+@example
+./ffmpeg -i in.avi -vfilters "vflip" out.avi
+@end example
+
 @bye
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index c5bf2bbb9c..f411d31528 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -13,5 +13,6 @@ OBJS = allfilters.o                                                     \
 
 OBJS-$(CONFIG_CROP_FILTER)    += vf_crop.o
 OBJS-$(CONFIG_NULL_FILTER)    += vf_null.o
+OBJS-$(CONFIG_VFLIP_FILTER)   += vf_vflip.o
 
 include $(SUBDIR)../subdir.mak
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 1104f610a8..d7bdb70b71 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -36,4 +36,5 @@ void avfilter_register_all(void)
 
     REGISTER_FILTER (CROP,crop,vf);
     REGISTER_FILTER (NULL,null,vf);
+    REGISTER_FILTER (VFLIP,vflip,vf);
 }
diff --git a/libavfilter/vf_vflip.c b/libavfilter/vf_vflip.c
new file mode 100644
index 0000000000..5a52479dc5
--- /dev/null
+++ b/libavfilter/vf_vflip.c
@@ -0,0 +1,102 @@
+/*
+ * copyright (c) 2007 Bobby Bingham
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file libavfilter/vf_vflip.c
+ * video vertical flip filter
+ */
+
+#include "avfilter.h"
+
+typedef struct {
+    int vsub;   ///< vertical chroma subsampling
+} FlipContext;
+
+static int config_input(AVFilterLink *link)
+{
+    FlipContext *flip = link->dst->priv;
+    int tmp;
+
+    avcodec_get_chroma_sub_sample(link->format, &tmp, &flip->vsub);
+
+    return 0;
+}
+
+static AVFilterPicRef *get_video_buffer(AVFilterLink *link, int perms,
+                                        int w, int h)
+{
+    FlipContext *flip = link->dst->priv;
+    int i;
+
+    AVFilterPicRef *picref = avfilter_get_video_buffer(link->dst->outputs[0],
+                                                       perms, w, h);
+
+    picref->data[0] += (h-1) * picref->linesize[0];
+    picref->linesize[0] = -picref->linesize[0];
+    for (i = 1; i < 4; i ++) {
+        if (picref->data[i]) {
+            picref->data[i] += ((h >> flip->vsub)-1) * picref->linesize[i];
+            picref->linesize[i] = -picref->linesize[i];
+        }
+    }
+
+    return picref;
+}
+
+static void start_frame(AVFilterLink *link, AVFilterPicRef *picref)
+{
+    FlipContext *flip = link->dst->priv;
+    AVFilterPicRef *ref2 = avfilter_ref_pic(picref, ~0);
+    int i;
+
+    ref2->data[0] += (link->h-1) * ref2->linesize[0];
+    ref2->linesize[0] = -ref2->linesize[0];
+    for (i = 1; i < 4; i ++) {
+        if (ref2->data[i]) {
+            ref2->data[i] += ((link->h >> flip->vsub)-1) * ref2->linesize[i];
+            ref2->linesize[i] = -ref2->linesize[i];
+        }
+    }
+
+    avfilter_start_frame(link->dst->outputs[0], ref2);
+}
+
+static void draw_slice(AVFilterLink *link, int y, int h)
+{
+    AVFilterContext *ctx = link->dst;
+
+    avfilter_draw_slice(ctx->outputs[0], link->h - (y+h), h);
+}
+
+AVFilter avfilter_vf_vflip = {
+    .name      = "vflip",
+    .priv_size = sizeof(FlipContext),
+
+    .inputs    = (AVFilterPad[]) {{ .name             = "default",
+                                    .type             = CODEC_TYPE_VIDEO,
+                                    .get_video_buffer = get_video_buffer,
+                                    .start_frame      = start_frame,
+                                    .draw_slice       = draw_slice,
+                                    .config_props     = config_input, },
+                                  { .name = NULL}},
+    .outputs   = (AVFilterPad[]) {{ .name             = "default",
+                                    .type             = CODEC_TYPE_VIDEO, },
+                                  { .name = NULL}},
+};