Implement cropdetect filter.

Originally committed as revision 25447 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 214 insertions, 0 deletions

diff --git a/libavfilter/vf_cropdetect.c b/libavfilter/vf_cropdetect.c
new file mode 100644
index 0000000000..d651519eee
--- /dev/null
+++ b/libavfilter/vf_cropdetect.c
@@ -0,0 +1,214 @@
+/*
+ * Copyright (C) 2002 A'rpi
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU 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
+ * border detection filter
+ * Ported from MPlayer libmpcodecs/vf_cropdetect.c.
+ */
+
+#include "libavcore/imgutils.h"
+#include "avfilter.h"
+
+typedef struct {
+    int x1, y1, x2, y2;
+    int limit;
+    int round;
+    int reset_count;
+    int frame_nb;
+    int max_pixsteps[4];
+} CropDetectContext;
+
+static int query_formats(AVFilterContext *ctx)
+{
+    static const enum PixelFormat pix_fmts[] = {
+        PIX_FMT_YUV420P, PIX_FMT_YUVJ420P,
+        PIX_FMT_YUV422P, PIX_FMT_YUVJ422P,
+        PIX_FMT_YUV444P, PIX_FMT_YUVJ444P,
+        PIX_FMT_YUV411P, PIX_FMT_GRAY8,
+        PIX_FMT_NV12,    PIX_FMT_NV21,
+        PIX_FMT_NONE
+    };
+
+    avfilter_set_common_formats(ctx, avfilter_make_format_list(pix_fmts));
+    return 0;
+}
+
+static int checkline(void *ctx, const unsigned char *src, int stride, int len, int bpp)
+{
+    int total = 0;
+    int div = len;
+
+    switch (bpp) {
+    case 1:
+        while (--len >= 0) {
+            total += src[0];
+            src += stride;
+        }
+        break;
+    case 3:
+    case 4:
+        while (--len >= 0) {
+            total += src[0] + src[1] + src[2];
+            src += stride;
+        }
+        div *= 3;
+        break;
+    }
+    total /= div;
+
+    av_log(ctx, AV_LOG_DEBUG, "total:%d\n", total);
+    return total;
+}
+
+static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
+{
+    CropDetectContext *cd = ctx->priv;
+
+    cd->limit = 24;
+    cd->round = 0;
+    cd->reset_count = 0;
+    cd->frame_nb = -2;
+
+    if (args)
+        sscanf(args, "%d:%d:%d", &cd->limit, &cd->round, &cd->reset_count);
+
+    av_log(ctx, AV_LOG_INFO, "limit:%d round:%d reset_count:%d\n",
+           cd->limit, cd->round, cd->reset_count);
+
+    return 0;
+}
+
+static int config_input(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx = inlink->dst;
+    CropDetectContext *cd = ctx->priv;
+
+    av_image_fill_max_pixsteps(cd->max_pixsteps, NULL,
+                               &av_pix_fmt_descriptors[inlink->format]);
+
+    cd->x1 = inlink->w - 1;
+    cd->y1 = inlink->h - 1;
+    cd->x2 = 0;
+    cd->y2 = 0;
+
+    return 0;
+}
+
+static void end_frame(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx = inlink->dst;
+    CropDetectContext *cd = ctx->priv;
+    AVFilterBufferRef *picref = inlink->cur_buf;
+    int bpp = cd->max_pixsteps[0];
+    int w, h, x, y, shrink_by;
+
+    // ignore first 2 frames - they may be empty
+    if (++cd->frame_nb > 0) {
+        // Reset the crop area every reset_count frames, if reset_count is > 0
+        if (cd->reset_count > 0 && cd->frame_nb > cd->reset_count) {
+            cd->x1 = picref->video->w-1;
+            cd->y1 = picref->video->h-1;
+            cd->x2 = 0;
+            cd->y2 = 0;
+            cd->frame_nb = 1;
+        }
+
+        for (y = 0; y < cd->y1; y++) {
+            if (checkline(ctx, picref->data[0] + picref->linesize[0] * y, bpp, picref->video->w, bpp) > cd->limit) {
+                cd->y1 = y;
+                break;
+            }
+        }
+
+        for (y = picref->video->h-1; y > cd->y2; y--) {
+            if (checkline(ctx, picref->data[0] + picref->linesize[0] * y, bpp, picref->video->w, bpp) > cd->limit) {
+                cd->y2 = y;
+                break;
+            }
+        }
+
+        for (y = 0; y < cd->x1; y++) {
+            if (checkline(ctx, picref->data[0] + bpp*y, picref->linesize[0], picref->video->h, bpp) > cd->limit) {
+                cd->x1 = y;
+                break;
+            }
+        }
+
+        for (y = picref->video->w-1; y > cd->x2; y--) {
+            if (checkline(ctx, picref->data[0] + bpp*y, picref->linesize[0], picref->video->h, bpp) > cd->limit) {
+                cd->x2 = y;
+                break;
+            }
+        }
+
+        // round x and y (up), important for yuv colorspaces
+        // make sure they stay rounded!
+        x = (cd->x1+1) & ~1;
+        y = (cd->y1+1) & ~1;
+
+        w = cd->x2 - x + 1;
+        h = cd->y2 - y + 1;
+
+        // w and h must be divisible by 2 as well because of yuv
+        // colorspace problems.
+        if (cd->round <= 1)
+            cd->round = 16;
+        if (cd->round % 2)
+            cd->round *= 2;
+
+        shrink_by = w % cd->round;
+        w -= shrink_by;
+        x += (shrink_by/2 + 1) & ~1;
+
+        shrink_by = h % cd->round;
+        h -= shrink_by;
+        y += (shrink_by/2 + 1) & ~1;
+
+        av_log(ctx, AV_LOG_INFO,
+               "x1:%d x2:%d y1:%d y2:%d w:%d h:%d x:%d y:%d pos:%"PRId64" pts:%f crop=%d:%d:%d:%d\n",
+               cd->x1, cd->x2, cd->y1, cd->y2, w, h, x, y, picref->pos,
+               picref->pts == AV_NOPTS_VALUE ? -1 : (double)picref->pts / AV_TIME_BASE,
+               w, h, x, y);
+    }
+
+    avfilter_end_frame(inlink->dst->outputs[0]);
+}
+
+AVFilter avfilter_vf_cropdetect = {
+    .name        = "cropdetect",
+    .description = NULL_IF_CONFIG_SMALL("Auto-detect crop size."),
+
+    .priv_size = sizeof(CropDetectContext),
+    .init      = init,
+
+    .query_formats = query_formats,
+
+    .inputs    = (AVFilterPad[]) {{ .name = "default",
+                                    .type             = AVMEDIA_TYPE_VIDEO,
+                                    .config_props     = config_input,
+                                    .get_video_buffer = avfilter_null_get_video_buffer,
+                                    .start_frame      = avfilter_null_start_frame,
+                                    .end_frame        = end_frame, },
+                                  { .name = NULL}},
+
+    .outputs   = (AVFilterPad[]) {{ .name             = "default",
+                                    .type             = AVMEDIA_TYPE_VIDEO },
+                                  { .name = NULL}},
+};