lavfi: add tile video filter.

Changelog

@@ -18,6 +18,7 @@ version next:
 - XBM encoder
 - RealAudio Lossless decoder
 - ZeroCodec decoder
+- tile video filter
 
 
 version 0.10:

doc/filters.texi

@@ -2682,6 +2682,22 @@ Complete example of a thumbnail creation with @command{ffmpeg}:
 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
 @end example
 
+@section tile
+
+Tile several successive frames together.
+
+It accepts as argument the tile size (i.e. the number of lines and columns)
+in the form "@var{w}x@var{h}".
+
+For example, produce 8×8 PNG tiles of all keyframes (@option{-skip_frame
+nokey}) in a movie:
+@example
+ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
+@end example
+The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
+duplicating each output frame to accomodate the originally detected frame
+rate.
+
 @section tinterlace
 
 Perform various types of temporal field interlacing.

libavfilter/Makefile

@@ -90,6 +90,7 @@ OBJS-$(CONFIG_SLICIFY_FILTER)                += vf_slicify.o
 OBJS-$(CONFIG_SPLIT_FILTER)                  += vf_split.o
 OBJS-$(CONFIG_SWAPUV_FILTER)                 += vf_swapuv.o
 OBJS-$(CONFIG_THUMBNAIL_FILTER)              += vf_thumbnail.o
+OBJS-$(CONFIG_TILE_FILTER)                   += vf_tile.o
 OBJS-$(CONFIG_TINTERLACE_FILTER)             += vf_tinterlace.o
 OBJS-$(CONFIG_TRANSPOSE_FILTER)              += vf_transpose.o
 OBJS-$(CONFIG_UNSHARP_FILTER)                += vf_unsharp.o

libavfilter/allfilters.c

@@ -98,6 +98,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER (SPLIT,       split,       vf);
     REGISTER_FILTER (SWAPUV,      swapuv,      vf);
     REGISTER_FILTER (THUMBNAIL,   thumbnail,   vf);
+    REGISTER_FILTER (TILE,        tile,        vf);
     REGISTER_FILTER (TINTERLACE,  tinterlace,  vf);
     REGISTER_FILTER (TRANSPOSE,   transpose,   vf);
     REGISTER_FILTER (UNSHARP,     unsharp,     vf);

libavfilter/vf_tile.c

@@ -0,0 +1,206 @@
+/*
+ * Copyright (c) 2012 Nicolas George
+ *
+ * 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
+ * tile video filter
+ */
+
+#include "libavutil/pixdesc.h"
+#include "avfilter.h"
+#include "drawutils.h"
+
+typedef struct {
+    unsigned w, h;
+    unsigned current;
+    FFDrawContext draw;
+    FFDrawColor blank;
+} TileContext;
+
+#define REASONABLE_SIZE 1024
+
+static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
+{
+    TileContext *tile = ctx->priv;
+    int r;
+    char dummy;
+
+    if (!args)
+        args = "6x5";
+    r = sscanf(args, "%ux%u%c", &tile->w, &tile->h, &dummy);
+    if (r != 2 || !tile->w || !tile->h)
+        return AVERROR(EINVAL);
+    if (tile->w > REASONABLE_SIZE || tile->h > REASONABLE_SIZE) {
+        av_log(ctx, AV_LOG_ERROR, "Tile size %ux%u is insane.\n",
+               tile->w, tile->h);
+        return AVERROR(EINVAL);
+    }
+    return 0;
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+    avfilter_set_common_pixel_formats(ctx, ff_draw_supported_pixel_formats(0));
+    return 0;
+}
+
+static int config_props(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    TileContext *tile   = ctx->priv;
+    AVFilterLink *inlink = ctx->inputs[0];
+
+    if (inlink->w > INT_MAX / tile->w) {
+        av_log(ctx, AV_LOG_ERROR, "Total width %ux%u is too much.\n",
+               tile->w, inlink->w);
+        return AVERROR(EINVAL);
+    }
+    if (inlink->h > INT_MAX / tile->h) {
+        av_log(ctx, AV_LOG_ERROR, "Total height %ux%u is too much.\n",
+               tile->h, inlink->h);
+        return AVERROR(EINVAL);
+    }
+    outlink->w = tile->w * inlink->w;
+    outlink->h = tile->h * inlink->h;
+    outlink->sample_aspect_ratio = inlink->sample_aspect_ratio;
+    ff_draw_init(&tile->draw, inlink->format, 0);
+    /* TODO make the color an option, or find an unified way of choosing it */
+    ff_draw_color(&tile->draw, &tile->blank, (uint8_t[]){ 0, 0, 0, -1 });
+
+    return 0;
+}
+
+/* Note: direct rendering is not possible since there is no guarantee that
+ * buffers are fed to start_frame in the order they were obtained from
+ * get_buffer (think B-frames). */
+
+static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
+{
+    AVFilterContext *ctx  = inlink->dst;
+    TileContext *tile    = ctx->priv;
+    AVFilterLink *outlink = ctx->outputs[0];
+
+    if (tile->current)
+        return;
+    outlink->out_buf = avfilter_get_video_buffer(outlink, AV_PERM_WRITE,
+                                                 outlink->w, outlink->h);
+    avfilter_copy_buffer_ref_props(outlink->out_buf, picref);
+    outlink->out_buf->video->w = outlink->w;
+    outlink->out_buf->video->h = outlink->h;
+    avfilter_start_frame(outlink, outlink->out_buf);
+}
+
+static void draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir)
+{
+    AVFilterContext *ctx  = inlink->dst;
+    TileContext *tile    = ctx->priv;
+    AVFilterLink *outlink = ctx->outputs[0];
+    unsigned x0 = inlink->w * (tile->current % tile->w);
+    unsigned y0 = inlink->h * (tile->current / tile->w);
+
+    ff_copy_rectangle2(&tile->draw,
+                       outlink->out_buf->data, outlink->out_buf->linesize,
+                       inlink ->cur_buf->data, inlink ->cur_buf->linesize,
+                       x0, y0 + y, 0, y, inlink->cur_buf->video->w, h);
+    /* TODO if tile->w == 1 && slice_dir is always 1, we could draw_slice
+     * immediately. */
+}
+
+static void draw_blank_frame(AVFilterContext *ctx)
+{
+    TileContext *tile    = ctx->priv;
+    AVFilterLink *inlink  = ctx->inputs[0];
+    AVFilterLink *outlink = ctx->outputs[0];
+    unsigned x0 = inlink->w * (tile->current % tile->w);
+    unsigned y0 = inlink->h * (tile->current / tile->w);
+
+    ff_fill_rectangle(&tile->draw, &tile->blank,
+                      outlink->out_buf->data, outlink->out_buf->linesize,
+                      x0, y0, inlink->w, inlink->h);
+    tile->current++;
+}
+static void end_last_frame(AVFilterContext *ctx)
+{
+    TileContext *tile    = ctx->priv;
+    AVFilterLink *outlink = ctx->outputs[0];
+
+    while (tile->current < tile->w * tile->h)
+        draw_blank_frame(ctx);
+    avfilter_draw_slice(outlink, 0, outlink->out_buf->video->h, 1);
+    avfilter_end_frame(outlink);
+    tile->current = 0;
+}
+
+static void end_frame(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx  = inlink->dst;
+    TileContext *tile    = ctx->priv;
+
+    avfilter_unref_buffer(inlink->cur_buf);
+    if (++tile->current == tile->w * tile->h)
+        end_last_frame(ctx);
+}
+
+static int request_frame(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    TileContext *tile   = ctx->priv;
+    AVFilterLink *inlink = ctx->inputs[0];
+    int r;
+
+    while (1) {
+        r = avfilter_request_frame(inlink);
+        if (r < 0) {
+            if (r == AVERROR_EOF && tile->current)
+                end_last_frame(ctx);
+            else
+                return r;
+            break;
+        }
+        if (!tile->current) /* done */
+            break;
+    }
+    return 0;
+}
+
+
+AVFilter avfilter_vf_tile = {
+    .name          = "tile",
+    .description   = NULL_IF_CONFIG_SMALL("Tile several successive frames together."),
+    .init          = init,
+    .query_formats = query_formats,
+    .priv_size     = sizeof(TileContext),
+    .inputs = (const AVFilterPad[]) {
+        { .name        = "default",
+          .type        = AVMEDIA_TYPE_VIDEO,
+          .start_frame = start_frame,
+          .draw_slice  = draw_slice,
+          .end_frame   = end_frame,
+          .min_perms   = AV_PERM_READ, },
+        { .name = NULL }
+    },
+    .outputs = (const AVFilterPad[]) {
+        { .name          = "default",
+          .type          = AVMEDIA_TYPE_VIDEO,
+          .config_props  = config_props,
+          .request_frame = request_frame },
+        { .name = NULL }
+    },
+};