y4menc: handle padded frames

Since y4menc inherits from GstVideoEncoder, it negotiates upstream buffer pools
with GstVideoMeta support. Thus, certain decoders might use that meta for
frames with padded memory. Nonetheless y4menc assumes only linear memory video
frames, without padding.

This patch will copy frames using gst_video_frame_copy() if buffer has
GstVideoMeta or its video info is padded with its custom video info. Otherwise,
it ill call the agnostic gst_buffer_copy() for a shallow copy.

Supersedes: !5042

Fixes: #2765
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8654>

subprojects/gst-plugins-good/gst/y4m/gsty4mencode.c

@@ -263,20 +263,85 @@ gst_y4m_encode_get_frame_header (GstY4mEncode * filter)
   return buf;
 }
 
+static GstBuffer *
+gst_y4m_encode_copy_buffer (GstY4mEncode * filter, GstBuffer * inbuf)
+{
+  GstVideoFrame in_frame, out_frame;
+  GstBuffer *outbuf = NULL;
+  gssize size;
+  gboolean copied;
+
+  if (!gst_video_frame_map (&in_frame, &filter->info, inbuf, GST_MAP_READ))
+    goto invalid_buffer;
+
+  /* TODO: use a bufferpool */
+  size = GST_VIDEO_INFO_SIZE (&filter->out_info);
+  outbuf = gst_buffer_new_allocate (NULL, size, NULL);
+  if (!outbuf) {
+    gst_video_frame_unmap (&in_frame);
+    goto invalid_buffer;
+  }
+
+  if (!gst_video_frame_map (&out_frame, &filter->out_info, outbuf,
+          GST_MAP_WRITE))
+    goto invalid_buffer;
+
+  copied = gst_video_frame_copy (&out_frame, &in_frame);
+
+  gst_video_frame_unmap (&out_frame);
+  gst_video_frame_unmap (&in_frame);
+
+  if (!copied)
+    goto invalid_buffer;
+
+  return outbuf;
+
+invalid_buffer:
+  {
+    GST_ELEMENT_WARNING (filter, STREAM, FORMAT, (NULL),
+        ("invalid video buffer"));
+    if (outbuf)
+      gst_buffer_unref (outbuf);
+    return NULL;
+  }
+}
+
+static gboolean
+gst_y4m_encode_buffer_has_padding (GstY4mEncode * y4enc, GstBuffer * inbuf)
+{
+  GstVideoMeta *vmeta = gst_buffer_get_video_meta (inbuf);
+  const GstVideoInfo *out_info = &y4enc->out_info;
+  int i;
+
+  if (!vmeta)
+    return y4enc->padded;
+
+  for (i = 0; i < vmeta->n_planes; i++) {
+    if (vmeta->offset[i] != GST_VIDEO_INFO_PLANE_OFFSET (out_info, i))
+      return TRUE;
+    if (vmeta->stride[i] != GST_VIDEO_INFO_PLANE_STRIDE (out_info, i))
+      return TRUE;
+  }
+
+  if (vmeta->alignment.padding_bottom != 0 ||
+      vmeta->alignment.padding_left != 0 ||
+      vmeta->alignment.padding_right != 0 || vmeta->alignment.padding_top != 0)
+    return TRUE;
+
+  return FALSE;
+}
 
 static GstFlowReturn
 gst_y4m_encode_handle_frame (GstVideoEncoder * encoder,
     GstVideoCodecFrame * frame)
 {
   GstY4mEncode *filter = GST_Y4M_ENCODE (encoder);
-  GstClockTime timestamp;
+  GstBuffer *outbuf;
 
   /* check we got some decent info from caps */
   if (GST_VIDEO_INFO_FORMAT (&filter->info) == GST_VIDEO_FORMAT_UNKNOWN)
     goto not_negotiated;
 
-  timestamp = GST_BUFFER_TIMESTAMP (frame->input_buffer);
-
   if (G_UNLIKELY (!filter->header)) {
     gboolean tff = FALSE;
 
@@ -294,13 +359,16 @@ gst_y4m_encode_handle_frame (GstVideoEncoder * encoder,
     frame->output_buffer = gst_y4m_encode_get_frame_header (filter);
   }
 
-  frame->output_buffer =
-      gst_buffer_append (frame->output_buffer,
-      gst_buffer_copy (frame->input_buffer));
-
-  /* decorate */
-  frame->output_buffer = gst_buffer_make_writable (frame->output_buffer);
-  GST_BUFFER_TIMESTAMP (frame->output_buffer) = timestamp;
+  if (gst_y4m_encode_buffer_has_padding (filter, frame->input_buffer)) {
+    outbuf = gst_y4m_encode_copy_buffer (filter, frame->input_buffer);
+    if (!outbuf) {
+      gst_video_encoder_drop_frame (encoder, frame);
+      return GST_FLOW_ERROR;
+    }
+  } else {
+    outbuf = gst_buffer_copy (frame->input_buffer);
+  }
+  frame->output_buffer = gst_buffer_append (frame->output_buffer, outbuf);
 
   return gst_video_encoder_finish_frame (encoder, frame);