From a95acbcc11555bc8d11fe219335efe7efc7c8955 Mon Sep 17 00:00:00 2001
From: Robert Mader <robert.mader@collabora.com>
Date: Sat, 17 Feb 2024 05:43:23 +0100
Subject: [PATCH] v4l2codecs: decoder: Clean up select_src_format()

Most importantly rely on video info helpers instead of manual parsing
of caps, which will allow us to use additional helpers in the future.

While on it, tighen the check for supported formats - failing that
indicates a bug in caps negotiation - and make some style changes.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5890>
---
 .../sys/v4l2codecs/gstv4l2decoder.c           | 39 ++++++++++++-------
 .../sys/v4l2codecs/gstv4l2decoder.h           |  2 +-
 2 files changed, 26 insertions(+), 15 deletions(-)

diff --git a/subprojects/gst-plugins-bad/sys/v4l2codecs/gstv4l2decoder.c b/subprojects/gst-plugins-bad/sys/v4l2codecs/gstv4l2decoder.c
index 1ce1251d0d..e0a992a94f 100644
--- a/subprojects/gst-plugins-bad/sys/v4l2codecs/gstv4l2decoder.c
+++ b/subprojects/gst-plugins-bad/sys/v4l2codecs/gstv4l2decoder.c
@@ -491,16 +491,15 @@ gst_v4l2_decoder_enum_src_formats (GstV4l2Decoder * self,
 
 gboolean
 gst_v4l2_decoder_select_src_format (GstV4l2Decoder * self, GstCaps * caps,
-    GstVideoInfo * info)
+    GstVideoInfo * vinfo)
 {
   gint ret;
   struct v4l2_format fmt = {
     .type = self->src_buf_type,
   };
-  GstStructure *str;
-  const gchar *format_str;
   GstVideoFormat format;
   guint32 pix_fmt;
+  GstVideoInfo tmp_vinfo;
 
   if (gst_caps_is_empty (caps))
     return FALSE;
@@ -511,16 +510,28 @@ gst_v4l2_decoder_select_src_format (GstV4l2Decoder * self, GstCaps * caps,
     return FALSE;
   }
 
-  caps = gst_caps_make_writable (caps);
-  str = gst_caps_get_structure (caps, 0);
-  gst_structure_fixate_field (str, "format");
+  gst_video_info_init (&tmp_vinfo);
 
-  format_str = gst_structure_get_string (str, "format");
-  format = gst_video_format_from_string (format_str);
+  GST_DEBUG_OBJECT (self, "Original caps: %" GST_PTR_FORMAT, caps);
+  caps = gst_caps_fixate (caps);
+  GST_DEBUG_OBJECT (self, "Fixated caps: %" GST_PTR_FORMAT, caps);
 
-  if (gst_v4l2_format_from_video_format (format, &pix_fmt) &&
-      pix_fmt != fmt.fmt.pix_mp.pixelformat) {
-    GST_DEBUG_OBJECT (self, "Trying to use peer format: %s ", format_str);
+  if (gst_video_info_from_caps (&tmp_vinfo, caps)) {
+    format = tmp_vinfo.finfo->format;
+  } else {
+    GST_WARNING_OBJECT (self, "Can't transform caps into video info!");
+    return FALSE;
+  }
+
+  if (!gst_v4l2_format_from_video_format (format, &pix_fmt)) {
+    GST_ERROR_OBJECT (self, "Unsupported V4L2 pixelformat %" GST_FOURCC_FORMAT,
+        GST_FOURCC_ARGS (fmt.fmt.pix_mp.pixelformat));
+    return FALSE;
+  }
+
+  if (pix_fmt != fmt.fmt.pix_mp.pixelformat) {
+    GST_WARNING_OBJECT (self, "Trying to use peer format: %s",
+        gst_video_format_to_string (format));
     fmt.fmt.pix_mp.pixelformat = pix_fmt;
 
     ret = ioctl (self->video_fd, VIDIOC_S_FMT, &fmt);
@@ -530,15 +541,15 @@ gst_v4l2_decoder_select_src_format (GstV4l2Decoder * self, GstCaps * caps,
     }
   }
 
-  if (!gst_v4l2_format_to_video_info (&fmt, info)) {
+  if (!gst_v4l2_format_to_video_info (&fmt, vinfo)) {
     GST_ERROR_OBJECT (self, "Unsupported V4L2 pixelformat %" GST_FOURCC_FORMAT,
         GST_FOURCC_ARGS (fmt.fmt.pix_mp.pixelformat));
     return FALSE;
   }
 
   GST_INFO_OBJECT (self, "Selected format %s %ix%i",
-      gst_video_format_to_string (info->finfo->format),
-      info->width, info->height);
+      gst_video_format_to_string (vinfo->finfo->format),
+      vinfo->width, vinfo->height);
 
   return TRUE;
 }
diff --git a/subprojects/gst-plugins-bad/sys/v4l2codecs/gstv4l2decoder.h b/subprojects/gst-plugins-bad/sys/v4l2codecs/gstv4l2decoder.h
index 146b8c26e0..c96efa2d55 100644
--- a/subprojects/gst-plugins-bad/sys/v4l2codecs/gstv4l2decoder.h
+++ b/subprojects/gst-plugins-bad/sys/v4l2codecs/gstv4l2decoder.h
@@ -72,7 +72,7 @@ GstCaps *         gst_v4l2_decoder_enum_src_formats (GstV4l2Decoder * self,
 
 gboolean          gst_v4l2_decoder_select_src_format (GstV4l2Decoder * self,
                                                       GstCaps * caps,
-                                                      GstVideoInfo * info);
+                                                      GstVideoInfo * vinfo);
 
 gint              gst_v4l2_decoder_request_buffers (GstV4l2Decoder * self,
                                                     GstPadDirection direction,