[FFmpeg-devel] [PATCH v4 1/7] vf_crop: Add support for cropping hardware frames

[Mark Thompson]

Set the cropping fields in the AVFrame.
---
On 26/03/2019 10:59, Song, Ruiling wrote:> 
> I think we need to make scale_vaapi evaluate input dimensions considering crop information. What do you think?

I agree.  But the cropping information is currently carried on the frame, not at any higher level (from the codec context or on the filter link), so we don't have any idea how big the output frames need to be at setup time when we have to set the size on the output link.  Making it work requires carrying more complete information through filter setup, similar to the problem with colour range and other properties which aren't reflected in the existing format.  (This is on my to-do list.)


 libavfilter/vf_crop.c | 74 +++++++++++++++++++++++++++++--------------
 1 file changed, 51 insertions(+), 23 deletions(-)

diff --git a/libavfilter/vf_crop.c b/libavfilter/vf_crop.c
index 84be4c7d0d..7f6b0f03d3 100644
--- a/libavfilter/vf_crop.c
+++ b/libavfilter/vf_crop.c
@@ -98,9 +98,17 @@ static int query_formats(AVFilterContext *ctx)
 
     for (fmt = 0; av_pix_fmt_desc_get(fmt); fmt++) {
         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(fmt);
-        if (!(desc->flags & (AV_PIX_FMT_FLAG_HWACCEL | AV_PIX_FMT_FLAG_BITSTREAM)) &&
-            !((desc->log2_chroma_w || desc->log2_chroma_h) && !(desc->flags & AV_PIX_FMT_FLAG_PLANAR)) &&
-            (ret = ff_add_format(&formats, fmt)) < 0)
+        if (desc->flags & AV_PIX_FMT_FLAG_BITSTREAM)
+            continue;
+        if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL)) {
+            // Not usable if there is any subsampling but the format is
+            // not planar (e.g. YUYV422).
+            if ((desc->log2_chroma_w || desc->log2_chroma_h) &&
+                !(desc->flags & AV_PIX_FMT_FLAG_PLANAR))
+                continue;
+        }
+        ret = ff_add_format(&formats, fmt);
+        if (ret < 0)
             return ret;
     }
 
@@ -157,8 +165,14 @@ static int config_input(AVFilterLink *link)
     s->var_values[VAR_POS]   = NAN;
 
     av_image_fill_max_pixsteps(s->max_step, NULL, pix_desc);
-    s->hsub = pix_desc->log2_chroma_w;
-    s->vsub = pix_desc->log2_chroma_h;
+
+    if (pix_desc->flags & AV_PIX_FMT_FLAG_HWACCEL) {
+        s->hsub = 1;
+        s->vsub = 1;
+    } else {
+        s->hsub = pix_desc->log2_chroma_w;
+        s->vsub = pix_desc->log2_chroma_h;
+    }
 
     if ((ret = av_expr_parse_and_eval(&res, (expr = s->w_expr),
                                       var_names, s->var_values,
@@ -237,9 +251,15 @@ fail_expr:
 static int config_output(AVFilterLink *link)
 {
     CropContext *s = link->src->priv;
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
 
-    link->w = s->w;
-    link->h = s->h;
+    if (desc->flags & AV_PIX_FMT_FLAG_HWACCEL) {
+        // Hardware frames adjust the cropping regions rather than
+        // changing the frame size.
+    } else {
+        link->w = s->w;
+        link->h = s->h;
+    }
     link->sample_aspect_ratio = s->out_sar;
 
     return 0;
@@ -252,9 +272,6 @@ static int filter_frame(AVFilterLink *link, AVFrame *frame)
     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
     int i;
 
-    frame->width  = s->w;
-    frame->height = s->h;
-
     s->var_values[VAR_N] = link->frame_count_out;
     s->var_values[VAR_T] = frame->pts == AV_NOPTS_VALUE ?
         NAN : frame->pts * av_q2d(link->time_base);
@@ -285,22 +302,33 @@ static int filter_frame(AVFilterLink *link, AVFrame *frame)
             (int)s->var_values[VAR_N], s->var_values[VAR_T], s->var_values[VAR_POS],
             s->x, s->y, s->x+s->w, s->y+s->h);
 
-    frame->data[0] += s->y * frame->linesize[0];
-    frame->data[0] += s->x * s->max_step[0];
-
-    if (!(desc->flags & AV_PIX_FMT_FLAG_PAL || desc->flags & FF_PSEUDOPAL)) {
-        for (i = 1; i < 3; i ++) {
-            if (frame->data[i]) {
-                frame->data[i] += (s->y >> s->vsub) * frame->linesize[i];
-                frame->data[i] += (s->x * s->max_step[i]) >> s->hsub;
+    if (desc->flags & AV_PIX_FMT_FLAG_HWACCEL) {
+        frame->crop_top   += s->y;
+        frame->crop_left  += s->x;
+        frame->crop_bottom = frame->height - frame->crop_top - frame->crop_bottom - s->h;
+        frame->crop_right  = frame->width  - frame->crop_left - frame->crop_right - s->w;
+
+    } else {
+        frame->width  = s->w;
+        frame->height = s->h;
+
+        frame->data[0] += s->y * frame->linesize[0];
+        frame->data[0] += s->x * s->max_step[0];
+
+        if (!(desc->flags & AV_PIX_FMT_FLAG_PAL || desc->flags & FF_PSEUDOPAL)) {
+            for (i = 1; i < 3; i ++) {
+                if (frame->data[i]) {
+                    frame->data[i] += (s->y >> s->vsub) * frame->linesize[i];
+                    frame->data[i] += (s->x * s->max_step[i]) >> s->hsub;
+                }
             }
         }
-    }
 
-    /* alpha plane */
-    if (frame->data[3]) {
-        frame->data[3] += s->y * frame->linesize[3];
-        frame->data[3] += s->x * s->max_step[3];
+        /* alpha plane */
+        if (frame->data[3]) {
+            frame->data[3] += s->y * frame->linesize[3];
+            frame->data[3] += s->x * s->max_step[3];
+        }
     }
 
     return ff_filter_frame(link->dst->outputs[0], frame);
-- 
2.20.1