From 2a1836f1831c616a956a25c964502dc795aafda4 Mon Sep 17 00:00:00 2001
From: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Date: Fri, 13 Mar 2020 14:23:39 -0400
Subject: [PATCH] v4l2codecs: Read driver provided stride

This implements driver stride support but only for single allocation buffers.
This code is imported from the original v4l2 plugin and adapted to the new
helper context.
---
 sys/v4l2codecs/gstv4l2format.c | 44 +++++++++++++++++++++++++++++++---
 1 file changed, 41 insertions(+), 3 deletions(-)

diff --git a/sys/v4l2codecs/gstv4l2format.c b/sys/v4l2codecs/gstv4l2format.c
index d7d7892003..39b5e2be4a 100644
--- a/sys/v4l2codecs/gstv4l2format.c
+++ b/sys/v4l2codecs/gstv4l2format.c
@@ -52,11 +52,37 @@ lookup_v4l2_fmt (guint v4l2_pix_fmt)
   return ret;
 }
 
+static gint
+extrapolate_stride (const GstVideoFormatInfo * finfo, gint plane, gint stride)
+{
+  gint estride;
+
+  switch (finfo->format) {
+    case GST_VIDEO_FORMAT_NV12:
+    case GST_VIDEO_FORMAT_NV12_64Z32:
+    case GST_VIDEO_FORMAT_NV21:
+    case GST_VIDEO_FORMAT_NV16:
+    case GST_VIDEO_FORMAT_NV61:
+    case GST_VIDEO_FORMAT_NV24:
+      estride = (plane == 0 ? 1 : 2) *
+          GST_VIDEO_FORMAT_INFO_SCALE_WIDTH (finfo, plane, stride);
+      break;
+    default:
+      estride = GST_VIDEO_FORMAT_INFO_SCALE_WIDTH (finfo, plane, stride);
+      break;
+  }
+
+  return estride;
+}
+
 gboolean
 gst_v4l2_format_to_video_info (struct v4l2_format * fmt,
     GstVideoInfo * out_info)
 {
   struct FormatEntry *entry = lookup_v4l2_fmt (fmt->fmt.pix_mp.pixelformat);
+  struct v4l2_pix_format_mplane *pix_mp = &fmt->fmt.pix_mp;
+  gint plane;
+  gsize offset = 0;
 
   if (!entry)
     return FALSE;
@@ -67,11 +93,23 @@ gst_v4l2_format_to_video_info (struct v4l2_format * fmt,
   }
 
   if (!gst_video_info_set_format (out_info, entry->gst_fmt,
-          fmt->fmt.pix_mp.width, fmt->fmt.pix_mp.height))
+          pix_mp->width, pix_mp->height))
     return FALSE;
 
-  /* FIXME play the extrapolation danse for single FDs formats, and copy over
-   * stride/offsets/size for the other formats */
+  /* TODO: We don't support multi-allocation yet */
+  g_return_val_if_fail (pix_mp->num_planes == 1, FALSE);
+  out_info->size = pix_mp->plane_fmt[0].sizeimage;
+
+  for (plane = 0; plane < GST_VIDEO_INFO_N_PLANES (out_info); plane++) {
+    gint stride = extrapolate_stride (out_info->finfo, plane,
+        pix_mp->plane_fmt[0].bytesperline);
+
+    out_info->stride[plane] = stride;
+    out_info->offset[plane] = offset;
+
+    offset += stride * GST_VIDEO_FORMAT_INFO_SCALE_HEIGHT (out_info->finfo,
+        plane, pix_mp->height);
+  }
 
   return TRUE;
 }