From 93be216910d9307e34cc6c700219ccf988a01938 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?V=C3=ADctor=20Manuel=20J=C3=A1quez=20Leal?=
 <vjaquez@igalia.com>
Date: Wed, 14 Aug 2024 10:51:13 +0200
Subject: [PATCH] pbutils: descriptions: use subsampling factor to get YUV
 subsampling

The algorithm used to determine the YUV subsampling string uses width and height
subsampling factor, not the raw subsampling. Otherwise all 4:2:0 YUV frames will
be detected as 4:4:4

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7360>
---
 .../gst-libs/gst/pbutils/descriptions.c       |  4 +--
 .../tests/check/libs/pbutils.c                | 27 +++++++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/subprojects/gst-plugins-base/gst-libs/gst/pbutils/descriptions.c b/subprojects/gst-plugins-base/gst-libs/gst/pbutils/descriptions.c
index 7e85b14ad0..e8a8827e91 100644
--- a/subprojects/gst-plugins-base/gst-libs/gst/pbutils/descriptions.c
+++ b/subprojects/gst-plugins-base/gst-libs/gst/pbutils/descriptions.c
@@ -471,8 +471,8 @@ format_info_get_desc (const FormatInfo * info, const GstCaps * caps)
       const gchar *subs;
       gint w_sub, h_sub, n_semi;
 
-      w_sub = GST_VIDEO_FORMAT_INFO_W_SUB (finfo, 1);
-      h_sub = GST_VIDEO_FORMAT_INFO_H_SUB (finfo, 1);
+      w_sub = 1 << GST_VIDEO_FORMAT_INFO_W_SUB (finfo, 1);
+      h_sub = 1 << GST_VIDEO_FORMAT_INFO_H_SUB (finfo, 1);
 
       if (w_sub == 1 && h_sub == 1) {
         subs = "4:4:4";
diff --git a/subprojects/gst-plugins-base/tests/check/libs/pbutils.c b/subprojects/gst-plugins-base/tests/check/libs/pbutils.c
index 37eea09208..b7b7245e2c 100644
--- a/subprojects/gst-plugins-base/tests/check/libs/pbutils.c
+++ b/subprojects/gst-plugins-base/tests/check/libs/pbutils.c
@@ -453,10 +453,36 @@ static const gchar *caps_strings[] = {
   /* raw video */
   "video/x-raw, format=(string)RGB16, width=(int)320, height=(int)240, framerate=(fraction)30/1, pixel-aspect-ratio=(fraction)1/1",
   "video/x-raw, format=(string)YUY2, width=(int)320, height=(int)240, framerate=(fraction)30/1",
+  "video/x-raw, format=(string)I420, width=(int)320, height=(int)240, framerate=(fraction)30/1",
+  "video/x-raw, format=(string)AYUV, width=(int)320, height=(int)240, framerate=(fraction)30/1",
   /* and a made-up format */
   "video/x-tpm"
 };
 
+static gboolean
+validate_video_subsampling (GstCaps * caps, gchar * desc)
+{
+  GstStructure *st;
+  const gchar *format;
+
+  st = gst_caps_get_structure (caps, 0);
+  if (!gst_structure_has_name (st, "video/x-raw"))
+    return TRUE;
+
+  format = gst_structure_get_string (st, "format");
+  if (!format)
+    return TRUE;
+
+  if (g_strcmp0 (format, "YUY2") == 0)
+    return g_str_has_suffix (desc, "4:2:2");
+  if (g_strcmp0 (format, "I420") == 0)
+    return g_str_has_suffix (desc, "4:2:0");
+  if (g_strcmp0 (format, "AYUV") == 0)
+    return g_str_has_suffix (desc, "4:4:4");
+
+  return TRUE;
+}
+
 GST_START_TEST (test_pb_utils_get_codec_description)
 {
   gint i;
@@ -475,6 +501,7 @@ GST_START_TEST (test_pb_utils_get_codec_description)
     fail_unless (desc != NULL);
     GST_LOG (" - codec   : %s", desc);
     fail_unless (g_utf8_validate (desc, -1, NULL));
+    fail_unless (validate_video_subsampling (caps, desc));
     g_free (desc);
     desc = gst_pb_utils_get_decoder_description (caps);
     fail_unless (desc != NULL);