Add scale filter.

Originally committed as revision 20519 to svn://svn.ffmpeg.org/ffmpeg/trunk

doc/libavfilter.texi

@@ -164,6 +164,31 @@ not specified it will use the default value of 16.
 Adding this in the beginning of filter chains should make filtering
 faster due to better use of the memory cache.
 
+@section scale
+
+Scale the input video to width:height and/or convert the image format.
+
+For example the command:
+
+@example
+./ffmpeg -i in.avi -vfilters "scale=200:100" out.avi
+@end example
+
+will scale the input video to a size of 200x100.
+
+If the input image format is different from the format requested by
+the next filter, the scale filter will convert the input to the
+requested format.
+
+If the value for ``width'' or ``height'' is 0, the respective input
+size is used for the output.
+
+If the value for ``width'' or ``height'' is -1, the scale filter will
+use, for the respective output size, a value that maintains the aspect
+ratio of the input image.
+
+The default value of ``width'' and ``height'' is 0.
+
 @section vflip
 
 Flip the input video vertically.

libavfilter/Makefile

@@ -16,6 +16,7 @@ OBJS-$(CONFIG_CROP_FILTER)                   += vf_crop.o
 OBJS-$(CONFIG_FORMAT_FILTER)                 += vf_format.o
 OBJS-$(CONFIG_NOFORMAT_FILTER)               += vf_format.o
 OBJS-$(CONFIG_NULL_FILTER)                   += vf_null.o
+OBJS-$(CONFIG_SCALE_FILTER)                  += vf_scale.o
 OBJS-$(CONFIG_SLICIFY_FILTER)                += vf_slicify.o
 OBJS-$(CONFIG_VFLIP_FILTER)                  += vf_vflip.o
 

libavfilter/allfilters.c

@@ -38,6 +38,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER (FORMAT, format, vf);
     REGISTER_FILTER (NOFORMAT, noformat, vf);
     REGISTER_FILTER (NULL, null, vf);
+    REGISTER_FILTER (SCALE, scale, vf);
     REGISTER_FILTER (SLICIFY, slicify, vf);
     REGISTER_FILTER (VFLIP, vflip, vf);
 }

libavfilter/avfilter.h

@@ -23,7 +23,7 @@
 #define AVFILTER_AVFILTER_H
 
 #define LIBAVFILTER_VERSION_MAJOR  1
-#define LIBAVFILTER_VERSION_MINOR  7
+#define LIBAVFILTER_VERSION_MINOR  8
 #define LIBAVFILTER_VERSION_MICRO  0
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \

libavfilter/vf_scale.c

@@ -0,0 +1,203 @@
+/*
+ * 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_scale.c
+ * scale video filter
+ */
+
+#include "avfilter.h"
+#include "libswscale/swscale.h"
+
+typedef struct {
+    struct SwsContext *sws;     ///< software scaler context
+
+    /**
+     * New dimensions. Special values are:
+     *   0 = original width/height
+     *  -1 = keep original aspect
+     */
+    int w, h;
+
+    int hsub, vsub;             ///< chroma subsampling
+    int slice_y;                ///< top of current output slice
+    int slice_dir;              ///< detected slice direction order for the current frame
+    int input_is_pal;           ///< set to 1 if the input format is paletted
+} ScaleContext;
+
+static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
+{
+    ScaleContext *scale = ctx->priv;
+
+    if (args)
+        sscanf(args, "%d:%d", &scale->w, &scale->h);
+
+    /* sanity check params */
+    if (scale->w <  -1 || scale->h <  -1) {
+        av_log(ctx, AV_LOG_ERROR, "Size values less than -1 are not acceptable.\n");
+        return -1;
+    }
+    if (scale->w == -1 && scale->h == -1)
+        scale->w = scale->h = 0;
+
+    return 0;
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    ScaleContext *scale = ctx->priv;
+    sws_freeContext(scale->sws);
+    scale->sws = NULL;
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+    AVFilterFormats *formats;
+
+    if (ctx->inputs[0]) {
+        formats = avfilter_all_colorspaces();
+        avfilter_formats_ref(formats, &ctx->inputs[0]->out_formats);
+    }
+    if (ctx->outputs[0]) {
+        formats = avfilter_all_colorspaces();
+        avfilter_formats_ref(formats, &ctx->outputs[0]->in_formats);
+    }
+
+    return 0;
+}
+
+static int config_props(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    AVFilterLink *inlink = outlink->src->inputs[0];
+    ScaleContext *scale = ctx->priv;
+    int64_t w, h;
+
+    if (!(w = scale->w))
+        w = inlink->w;
+    if (!(h = scale->h))
+        h = inlink->h;
+    if (w == -1)
+        w = av_rescale(h, inlink->w, inlink->h);
+    if (h == -1)
+        h = av_rescale(w, inlink->h, inlink->w);
+
+    if (w > INT_MAX || h > INT_MAX ||
+        (h * inlink->w) > INT_MAX  ||
+        (w * inlink->h) > INT_MAX)
+        av_log(ctx, AV_LOG_ERROR, "Rescaled value for width or height is too big.\n");
+
+    outlink->w = w;
+    outlink->h = h;
+
+    /* TODO: make algorithm configurable */
+    scale->sws = sws_getContext(inlink ->w, inlink ->h, inlink ->format,
+                                outlink->w, outlink->h, outlink->format,
+                                SWS_BILINEAR, NULL, NULL, NULL);
+
+    av_log(ctx, AV_LOG_INFO, "w:%d h:%d fmt:%s\n",
+           outlink->w, outlink->h, avcodec_get_pix_fmt_name(outlink->format));
+
+    avcodec_get_chroma_sub_sample(outlink->format, &scale->hsub, &scale->vsub);
+
+    scale->input_is_pal = inlink->format == PIX_FMT_PAL8      ||
+                          inlink->format == PIX_FMT_BGR4_BYTE ||
+                          inlink->format == PIX_FMT_RGB4_BYTE ||
+                          inlink->format == PIX_FMT_BGR8      ||
+                          inlink->format == PIX_FMT_RGB8;
+
+    return !scale->sws;
+}
+
+static void start_frame(AVFilterLink *link, AVFilterPicRef *picref)
+{
+    ScaleContext *scale = link->dst->priv;
+    AVFilterLink *outlink = link->dst->outputs[0];
+    AVFilterPicRef *outpicref;
+
+    outpicref = avfilter_get_video_buffer(outlink, AV_PERM_WRITE, outlink->w, outlink->h);
+    outpicref->pts = picref->pts;
+    outlink->outpic = outpicref;
+
+    av_reduce(&outpicref->pixel_aspect.num, &outpicref->pixel_aspect.den,
+              (int64_t)picref->pixel_aspect.num * outlink->h * link->w,
+              (int64_t)picref->pixel_aspect.den * outlink->w * link->h,
+              INT_MAX);
+
+    scale->slice_dir = 0;
+    avfilter_start_frame(outlink, avfilter_ref_pic(outpicref, ~0));
+}
+
+static void draw_slice(AVFilterLink *link, int y, int h)
+{
+    ScaleContext *scale = link->dst->priv;
+    int out_h;
+    AVFilterPicRef *cur_pic = link->cur_pic;
+    uint8_t *data[4];
+
+    if (!scale->slice_dir) {
+        if (y != 0 && y + h != link->h) {
+            av_log(scale, AV_LOG_ERROR, "Slices start in the middle!\n");
+            return;
+        }
+        scale->slice_dir = y ?                       -1 : 1;
+        scale->slice_y   = y ? link->dst->outputs[0]->h : y;
+    }
+
+    data[0] = cur_pic->data[0] +  y               * cur_pic->linesize[0];
+    data[1] = scale->input_is_pal ?
+              cur_pic->data[1] :
+              cur_pic->data[1] + (y>>scale->vsub) * cur_pic->linesize[1];
+    data[2] = cur_pic->data[2] + (y>>scale->vsub) * cur_pic->linesize[2];
+    data[3] = cur_pic->data[3] +  y               * cur_pic->linesize[3];
+
+    out_h = sws_scale(scale->sws, data, cur_pic->linesize, y, h,
+                      link->dst->outputs[0]->outpic->data,
+                      link->dst->outputs[0]->outpic->linesize);
+
+    if (scale->slice_dir == -1)
+        scale->slice_y -= out_h;
+    avfilter_draw_slice(link->dst->outputs[0], scale->slice_y, out_h);
+    if (scale->slice_dir == 1)
+        scale->slice_y += out_h;
+}
+
+AVFilter avfilter_vf_scale = {
+    .name      = "scale",
+    .description = "Scale the input video to width:height size and/or convert the image format.",
+
+    .init      = init,
+    .uninit    = uninit,
+
+    .query_formats = query_formats,
+
+    .priv_size = sizeof(ScaleContext),
+
+    .inputs    = (AVFilterPad[]) {{ .name             = "default",
+                                    .type             = CODEC_TYPE_VIDEO,
+                                    .start_frame      = start_frame,
+                                    .draw_slice       = draw_slice,
+                                    .min_perms        = AV_PERM_READ, },
+                                  { .name = NULL}},
+    .outputs   = (AVFilterPad[]) {{ .name             = "default",
+                                    .type             = CODEC_TYPE_VIDEO,
+                                    .config_props     = config_props, },
+                                  { .name = NULL}},
+};