Add video filter to manipulate aspect ratio

Originally committed as revision 22573 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 135 insertions, 0 deletions

diff --git a/libavfilter/vf_aspect.c b/libavfilter/vf_aspect.c
new file mode 100644
index 0000000000..f1961ce217
--- /dev/null
+++ b/libavfilter/vf_aspect.c
@@ -0,0 +1,135 @@
+/*
+ * Aspect ratio modification video filter
+ * Copyright (c) 2010 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_aspect.c
+ * aspect ratio modification video filter
+ */
+
+#include "avfilter.h"
+
+typedef struct {
+    AVRational aspect;
+} AspectContext;
+
+static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
+{
+    AspectContext *aspect = ctx->priv;
+    double  ratio;
+    int64_t gcd;
+
+    if(args) {
+        if(sscanf(args, "%d:%d", &aspect->aspect.num, &aspect->aspect.den) < 2) {
+            if(sscanf(args, "%lf", &ratio) < 1)
+                return -1;
+            aspect->aspect = av_d2q(ratio, 100);
+        } else {
+            gcd = av_gcd(FFABS(aspect->aspect.num), FFABS(aspect->aspect.den));
+            if(gcd) {
+                aspect->aspect.num /= gcd;
+                aspect->aspect.den /= gcd;
+            }
+        }
+    }
+
+    if(aspect->aspect.den == 0)
+        aspect->aspect = (AVRational) {0, 1};
+
+    return 0;
+}
+
+
+static AVFilterPicRef *get_video_buffer(AVFilterLink *link, int perms,
+                                        int w, int h)
+{
+    return avfilter_get_video_buffer(link->dst->outputs[0], perms, w, h);
+}
+
+static void start_frame(AVFilterLink *link, AVFilterPicRef *picref)
+{
+    AspectContext *aspect = link->dst->priv;
+
+    picref->pixel_aspect = aspect->aspect;
+    avfilter_start_frame(link->dst->outputs[0], picref);
+}
+
+static void end_frame(AVFilterLink *link)
+{
+    avfilter_end_frame(link->dst->outputs[0]);
+}
+
+#if CONFIG_ASPECT_FILTER
+/* for aspect filter, convert from frame aspect ratio to pixel aspect ratio */
+static int frameaspect_config_props(AVFilterLink *inlink)
+{
+    AspectContext *aspect = inlink->dst->priv;
+
+    av_reduce(&aspect->aspect.num, &aspect->aspect.den,
+               aspect->aspect.num * inlink->h,
+               aspect->aspect.den * inlink->w, 100);
+
+    return 0;
+}
+
+AVFilter avfilter_vf_aspect = {
+    .name      = "aspect",
+    .description = NULL_IF_CONFIG_SMALL("Set the frame aspect ratio."),
+
+    .init      = init,
+
+    .priv_size = sizeof(AspectContext),
+
+    .inputs    = (AVFilterPad[]) {{ .name             = "default",
+                                    .type             = CODEC_TYPE_VIDEO,
+                                    .config_props     = frameaspect_config_props,
+                                    .get_video_buffer = get_video_buffer,
+                                    .start_frame      = start_frame,
+                                    .end_frame        = end_frame },
+                                  { .name = NULL}},
+
+    .outputs   = (AVFilterPad[]) {{ .name             = "default",
+                                    .type             = CODEC_TYPE_VIDEO, },
+                                  { .name = NULL}},
+};
+#endif /* CONFIG_ASPECT_FILTER */
+
+#if CONFIG_PIXELASPECT_FILTER
+AVFilter avfilter_vf_pixelaspect = {
+    .name      = "pixelaspect",
+    .description = NULL_IF_CONFIG_SMALL("Set the pixel aspect ratio."),
+
+    .init      = init,
+
+    .priv_size = sizeof(AspectContext),
+
+    .inputs    = (AVFilterPad[]) {{ .name             = "default",
+                                    .type             = CODEC_TYPE_VIDEO,
+                                    .get_video_buffer = get_video_buffer,
+                                    .start_frame      = start_frame,
+                                    .end_frame        = end_frame },
+                                  { .name = NULL}},
+
+    .outputs   = (AVFilterPad[]) {{ .name             = "default",
+                                    .type             = CODEC_TYPE_VIDEO, },
+                                  { .name = NULL}},
+};
+#endif /* CONFIG_PIXELASPECT_FILTER */
+