[FFmpeg-soc] [PATCH] Add fade filter to libavfilter
Brandon Mintern
bmintern at gmail.com
Wed Mar 31 07:23:29 CEST 2010
On Wed, Mar 31, 2010 at 12:43 AM, Brandon Mintern <bmintern at gmail.com> wrote:
> I am happy to present my first-ever open source code contribution, a
> "fade" filter for libavfilter!
[snip]
Ugh... I found a very minor bug that will cause a small rounding error
while calculating the chroma planes. The bug is fixed in this new
patch, and http://bmintern.homeunix.com/~brandon/vf_fade.patch is
updated with the change.
I'm looking forward to hearing some feedback,
Brandon
Index: allfilters.c
===================================================================
--- allfilters.c (revision 5726)
+++ allfilters.c (working copy)
@@ -37,6 +37,7 @@
REGISTER_FILTER (ASPECT, aspect, vf);
REGISTER_FILTER (CROP, crop, vf);
REGISTER_FILTER (DRAWBOX, drawbox, vf);
+ REGISTER_FILTER (FADE, fade, vf);
REGISTER_FILTER (FIFO, fifo, vf);
REGISTER_FILTER (FORMAT, format, vf);
REGISTER_FILTER (FPS, fps, vf);
Index: vf_fade.c
===================================================================
--- vf_fade.c (revision 0)
+++ vf_fade.c (revision 0)
@@ -0,0 +1,168 @@
+/*
+ * video fade filter
+ * copyright (c) 2010 Brandon Mintern
+ * based heavily on vf_negate.c which is 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
+ */
+
+/*
+ # A few usage examples follow, usable too as test scenarios.
+
+ # Fade in first 30 frames of video
+ ffmpeg -i input.avi -vfilters fade=in:1:30 output.avi
+
+ # Fade out last 45 frames of a 200-frame video
+ ffmpeg -i input.avi -vfilters fade=out:156:45 output.avi
+
+ # Fade in first 25 frames and fade out last 25 frames of a 1000-frame video
+ ffmpeg -i input.avi -vfilters "fade=in:1:25, fade=out:976:25" output.avi
+
+ # Make first 5 frames black, then fade in from frame 6-25
+ ffmpeg -i input.avi -vfilters "fade=in:6:20" output.avi
+*/
+
+#include "avfilter.h"
+
+typedef struct
+{
+ float fade_factor, fade_per_frame;
+ unsigned int frame_index, start_frame, stop_frame;
+ int hsub, vsub;
+} FadeContext;
+
+static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
+{
+ FadeContext *fade = ctx->priv;
+ unsigned int frames;
+ char in_out[4];
+
+ if(args && sscanf(args, " %3[^:]:%u:%u", in_out,
+ &fade->start_frame, &frames) == 3) {
+ frames = frames ? frames : 1;
+ fade->fade_per_frame = 1.0 / frames;
+ if (!strcmp(in_out, "in"))
+ fade->fade_factor = 0.0;
+ else if (!strcmp(in_out, "out")) {
+ fade->fade_per_frame = -fade->fade_per_frame;
+ fade->fade_factor = 1.0;
+ }
+ else {
+ av_log(ctx, AV_LOG_ERROR,
+ "init() 1st arg must be 'in' or 'out':'%s'\n", in_out);
+ return -1;
+ }
+
+ fade->frame_index = 1;
+ fade->start_frame = fade->start_frame ? fade->start_frame : 1;
+ fade->stop_frame = fade->start_frame + frames;
+ return 0;
+ }
+ av_log(ctx, AV_LOG_ERROR,
+ "init() expected 3 arguments '(in|out):#:#':'%s'\n", args);
+ return -1;
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+ enum PixelFormat pix_fmts[] = {
+ PIX_FMT_YUV444P, PIX_FMT_YUV422P, PIX_FMT_YUV420P,
+ PIX_FMT_YUV411P, PIX_FMT_YUV410P,
+ PIX_FMT_YUVJ444P, PIX_FMT_YUVJ422P, PIX_FMT_YUVJ420P,
+ PIX_FMT_YUV440P, PIX_FMT_YUVJ440P,
+ PIX_FMT_NONE
+ };
+
+ avfilter_set_common_formats(ctx, avfilter_make_format_list(pix_fmts));
+ return 0;
+}
+
+static int config_props(AVFilterLink *link)
+{
+ FadeContext *fade = link->dst->priv;
+ avcodec_get_chroma_sub_sample(link->format, &fade->hsub, &fade->vsub);
+ return 0;
+}
+
+
+static void start_frame(AVFilterLink *link, AVFilterPicRef *picref)
+{
+ FadeContext *fade = link->dst->priv;
+ if(fade->frame_index >= fade->start_frame &&
+ fade->frame_index < fade->stop_frame) {
+ fade->fade_factor += fade->fade_per_frame;
+ }
+ fade->frame_index++;
+ avfilter_default_start_frame(link, picref);
+}
+
+static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
+{
+ FadeContext *fade = link->dst->priv;
+ AVFilterPicRef *in = link->cur_pic;
+ AVFilterPicRef *out = link->dst->outputs[0]->outpic;
+ uint8_t *inrow, *outrow;
+ int i, j, plane;
+
+ /* luma plane */
+ inrow = in-> data[0] + y * in-> linesize[0];
+ outrow = out->data[0] + y * out->linesize[0];
+ for(i = 0; i < h; i ++) {
+ for(j = 0; j < link->w; j ++)
+ outrow[j] = (uint8_t) ((float) inrow[j] * fade->fade_factor + 0.5);
+ inrow += in-> linesize[0];
+ outrow += out->linesize[0];
+ }
+
+ /* chroma planes */
+ for(plane = 1; plane < 3; plane ++) {
+ inrow = in-> data[plane] + (y >> fade->vsub) * in-> linesize[plane];
+ outrow = out->data[plane] + (y >> fade->vsub) * out->linesize[plane];
+
+ for(i = 0; i < h >> fade->vsub; i ++) {
+ for(j = 0; j < link->w >> fade->hsub; j ++)
+ outrow[j] = (int) (128.5 + (inrow[j]-128) * fade->fade_factor);
+ inrow += in-> linesize[plane];
+ outrow += out->linesize[plane];
+ }
+ }
+
+ avfilter_draw_slice(link->dst->outputs[0], y, h, slice_dir);
+}
+
+AVFilter avfilter_vf_fade =
+{
+ .name = "fade",
+
+ .init = init,
+
+ .priv_size = sizeof(FadeContext),
+
+ .query_formats = query_formats,
+
+ .inputs = (AVFilterPad[]) {{ .name = "default",
+ .type = CODEC_TYPE_VIDEO,
+ .start_frame = start_frame,
+ .draw_slice = draw_slice,
+ .config_props = config_props,
+ .min_perms = AV_PERM_READ, },
+ { .name = NULL}},
+ .outputs = (AVFilterPad[]) {{ .name = "default",
+ .type = CODEC_TYPE_VIDEO, },
+ { .name = NULL}},
+};
+
Index: Makefile
===================================================================
--- Makefile (revision 5726)
+++ Makefile (working copy)
@@ -18,6 +18,7 @@
OBJS-$(CONFIG_ASPECT_FILTER) += vf_aspect.o
OBJS-$(CONFIG_CROP_FILTER) += vf_crop.o
OBJS-$(CONFIG_DRAWBOX_FILTER) += vf_drawbox.o
+OBJS-$(CONFIG_FADE_FILTER) += vf_fade.o
OBJS-$(CONFIG_FIFO_FILTER) += vf_fifo.o
OBJS-$(CONFIG_FORMAT_FILTER) += vf_format.o
OBJS-$(CONFIG_FPS_FILTER) += vf_fps.o
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