lavfi/vflip: Support Bayer vertical flip.

Fixes ticket #8819.

libavfilter/vf_vflip.c

@@ -33,6 +33,7 @@
 typedef struct FlipContext {
     const AVClass *class;
     int vsub;   ///< vertical chroma subsampling
+    int bayer;
 } FlipContext;
 
 static const AVOption vflip_options[] = {
@@ -47,6 +48,7 @@ static int config_input(AVFilterLink *link)
     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
 
     flip->vsub = desc->log2_chroma_h;
+    flip->bayer = !!(desc->flags & AV_PIX_FMT_FLAG_BAYER);
 
     return 0;
 }
@@ -74,11 +76,43 @@ static AVFrame *get_video_buffer(AVFilterLink *link, int w, int h)
     return frame;
 }
 
+static int flip_bayer(AVFilterLink *link, AVFrame *in)
+{
+    AVFilterContext *ctx  = link->dst;
+    AVFilterLink *outlink = ctx->outputs[0];
+    AVFrame *out;
+    uint8_t *inrow = in->data[0], *outrow;
+    int i, width = outlink->w << (av_pix_fmt_desc_get(link->format)->comp[0].step > 1);
+    if (outlink->h & 1) {
+        av_log(ctx, AV_LOG_ERROR, "Bayer vertical flip needs even height\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
+    if (!out) {
+        av_frame_free(&in);
+        return AVERROR(ENOMEM);
+    }
+    av_frame_copy_props(out, in);
+    outrow = out->data[0] + out->linesize[0] * (outlink->h - 2);
+    for (i = 0; i < outlink->h >> 1; i++) {
+        memcpy(outrow, inrow, width);
+        memcpy(outrow + out->linesize[0], inrow + in->linesize[0], width);
+        inrow  += 2 *  in->linesize[0];
+        outrow -= 2 * out->linesize[0];
+    }
+    av_frame_free(&in);
+    return ff_filter_frame(outlink, out);
+}
+
 static int filter_frame(AVFilterLink *link, AVFrame *frame)
 {
     FlipContext *flip = link->dst->priv;
     int i;
 
+    if (flip->bayer)
+        return flip_bayer(link, frame);
+
     for (i = 0; i < 4; i ++) {
         int vsub = i == 1 || i == 2 ? flip->vsub : 0;
         int height = AV_CEIL_RSHIFT(link->h, vsub);