diff --git a/README.html b/README.html
index f5b1591..ad3444b 100644
--- a/README.html
+++ b/README.html
@@ -330,7 +330,7 @@ plugins (Non-Debian-based Linux or *BSD)</h3>
 <li><p><strong>Red Hat, or clones like CentOS (now continued as Rocky
 Linux or Alma Linux):</strong> (sudo dnf install, or sudo yum install)
 gstreamer1-libav gstreamer1-plugins-bad-free (+ gstreamer1-vaapi for
-intel graphics). <em>You may need to get some of them (in particular
+Intel/AMD graphics). <em>You may need to get some of them (in particular
 gstreamer1-libav) from <a href="https://rpmfusion.org">rpmfusion.org</a>
 (which provides packages including plugins that RedHat does not ship for
 license reasons). [In recent <strong>Fedora</strong>, the libav plugin
@@ -342,19 +342,19 @@ fail to start, with error: <strong>no element “avdec_aac”</strong>
 ]</em>.</p></li>
 <li><p><strong>OpenSUSE:</strong> (sudo zypper install)
 gstreamer-plugins-libav gstreamer-plugins-bad (+ gstreamer-plugins-vaapi
-for Intel graphics). <em>In some cases, you may need to use gstreamer or
-libav* packages for OpenSUSE from <a
+for Intel/AMD graphics). <em>In some cases, you may need to use
+gstreamer or libav* packages for OpenSUSE from <a
 href="https://ftp.gwdg.de/pub/linux/misc/packman/suse/">Packman</a>
 “Essentials” (which provides packages including plugins that OpenSUSE
 does not ship for license reasons; recommendation: after adding the
 Packman repository, use the option in YaST Software management to switch
 all system packages for multimedia to Packman).</em></p></li>
 <li><p><strong>Arch Linux</strong> (sudo pacman -Syu) gst-plugins-good
-gst-plugins-bad gst-libav (+ gstreamer-vaapi for Intel
+gst-plugins-bad gst-libav (+ gstreamer-vaapi for Intel/AMD
 graphics).</p></li>
 <li><p><strong>FreeBSD:</strong> (sudo pkg install) gstreamer1-libav,
 gstreamer1-plugins, gstreamer1-plugins-* (* = core, good, bad, x, gtk,
-gl, vulkan, pulse, v4l2, …), (+ gstreamer1-vaapi for Intel
+gl, vulkan, pulse, v4l2, …), (+ gstreamer1-vaapi for Intel/AMD
 graphics).</p></li>
 </ul>
 <h3 id="starting-and-running-uxplay">Starting and running UxPlay</h3>
@@ -396,7 +396,7 @@ the video and audio streams were both played as soon as possible after
 they arrived (the GStreamer “<em>sync=false</em>” method), with a
 GStreamer internal clock used to try to keep them synchronized.
 <strong>Starting with UxPlay-1.64, the other method (GStreamer’s
-“<em>sync-true</em>” mode), which uses timestamps in the audio and video
+“<em>sync=true</em>” mode), which uses timestamps in the audio and video
 streams sent by the client, is the new default</strong>. On
 low-decoding-power UxPlay hosts (such as Raspberry Pi 3 models) this
 will drop video frames that cannot be decoded in time to play with the
@@ -405,7 +405,7 @@ audio, making the video jerky, but still synchronized.</p></li>
 <p>The older method which does not drop late video frames worked well on
 more powerful systems, and is still available with the UxPlay option
 “<code>-vsync no</code>”; this method is adapted to “live streaming”,
-and may be better when Using UxPlay as a second monitor for a Mac
+and may be better when using UxPlay as a second monitor for a Mac
 computer, for example, while the new default timestamp-based method is
 best for watching a video, to keep lip movements and voices
 synchronized. (Without use of timestamps, video will eventually lag
@@ -454,7 +454,7 @@ instructions for Raspberry Pi (tested on R Pi 4 model B 8GB and R Pi 3
 model B+)</strong>:</h3>
 <ul>
 <li><p>If you use the software-only (h264) video-decoding UxPlay option
-<code>-avdec</code>, it now works better that earlier, with the new
+<code>-avdec</code>, it now works better than earlier, with the new
 default timestamp-based synchronization to keep audio and video
 synchronized.</p></li>
 <li><p>For best performance, the Raspberry Pi needs the GStreamer
@@ -542,7 +542,7 @@ uninstalled after building uxplay, if you wish.</p>
 <li><p>If you use Homebrew:
 <code>brew install libplist openssl@3</code></p></li>
 <li><p>if you use MacPorts:
-<code>sudo port install plist-devel openssl3</code></p></li>
+<code>sudo port install libplist-devel openssl3</code></p></li>
 </ul>
 <p>Otherwise, build libplist and openssl from source: see instructions
 near the end of this README; requires development tools (autoconf,
@@ -589,6 +589,14 @@ the UxPlay source directory (“UxPlay-master” for zipfile downloads,
 “UxPlay” for “git clone” downloads) and build/install with “cmake . ;
 make ; sudo make install” (same as for Linux).</p>
 <ul>
+<li><p>Running UxPlay while checking for GStreamer warnings (do this
+with “export GST_DEBUG=2” before runnng UxPlay) reveals that with the
+default (since UxPlay 1.64) use of timestamps for video synchonization,
+many video frames are being dropped (only on macOS), perhaps due to
+another error (about videometa) that shows up in the GStreamer warnings.
+<strong>Recommendation: use the new UxPlay “no timestamp” option
+“<code>-vsync no</code>”</strong> (you can add a line “vsync no” in the
+uxplayrc configuration file).</p></li>
 <li><p>On macOS with this installation of GStreamer, the only videosinks
 available seem to be glimagesink (default choice made by autovideosink)
 and osxvideosink. The window title does not show the Airplay server
@@ -764,7 +772,7 @@ reports to the client, but at present changing this does not seem to
 have any effect</em>.</p>
 <p><strong>-async no</strong>. This is the still the default behavior in
 Audio-only mode, but this option may be useful as a command-line option
-to switch of a <code>-async</code> option set in a “uxplayrc”
+to switch off a <code>-async</code> option set in a “uxplayrc”
 configuration file.</p>
 <p><strong>-s wxh</strong> (e.g. -s 1920x1080 , which is the default )
 sets the display resolution (width and height, in pixels). (This may be
@@ -1073,7 +1081,7 @@ href="https://github.com/FDH2/UxPlay/wiki/Gstreamer-Video4Linux2-plugin-patches"
 for patches). This is fixed in GStreamer-1.22, and by backport patches
 from this in distributions such as Raspberry Pi OS (Bullseye):
 <strong>use option <code>-bt709</code> with the GStreamer-1.18.4 from
-Raspberry Pi OS</strong>.. This also needs the bcm2835-codec kernel
+Raspberry Pi OS</strong>. This also needs the bcm2835-codec kernel
 module that is not in the standard Linux kernel (it is available in
 Raspberry Pi OS, Ubuntu and Manjaro).</p>
 <ul>
diff --git a/README.md b/README.md
index 1ca51a8..1ec0458 100644
--- a/README.md
+++ b/README.md
@@ -280,7 +280,7 @@ installed, depending on how your audio is set up.
 
 * **Red Hat, or clones like CentOS (now continued as Rocky Linux or Alma Linux):** 
 (sudo dnf install, or sudo yum install) gstreamer1-libav gstreamer1-plugins-bad-free (+ gstreamer1-vaapi
-for intel graphics). _You may need to get some of them (in particular gstreamer1-libav) from [rpmfusion.org](https://rpmfusion.org)
+for Intel/AMD graphics). _You may need to get some of them (in particular gstreamer1-libav) from [rpmfusion.org](https://rpmfusion.org)
 (which provides packages including plugins that RedHat does not ship for license reasons).
 [In recent **Fedora**, the libav plugin package is renamed to  "gstreamer1-plugin-libav",
 which now needs the RPM Fusion package ffmpeg-libs for the
@@ -291,7 +291,7 @@ error: **no element "avdec_aac"** ]_.
  * **OpenSUSE:**
 (sudo zypper install)
 gstreamer-plugins-libav gstreamer-plugins-bad (+ gstreamer-plugins-vaapi
-for Intel graphics). _In some cases,  you may need to use gstreamer or libav* packages for OpenSUSE
+for Intel/AMD graphics). _In some cases,  you may need to use gstreamer or libav* packages for OpenSUSE
 from [Packman](https://ftp.gwdg.de/pub/linux/misc/packman/suse/) "Essentials"
 (which provides packages including plugins that OpenSUSE does not ship for license reasons; recommendation: after adding the
 Packman repository, use the option in YaST Software management to switch
@@ -299,10 +299,10 @@ all system packages for multimedia to Packman)._
 
 * **Arch Linux**
 (sudo pacman -Syu) gst-plugins-good gst-plugins-bad gst-libav (+ gstreamer-vaapi
-for Intel graphics). 
+for Intel/AMD graphics). 
 
  * **FreeBSD:** (sudo pkg install)  gstreamer1-libav, gstreamer1-plugins, gstreamer1-plugins-*
-(\* = core, good,  bad, x, gtk, gl, vulkan, pulse, v4l2,  ...), (+ gstreamer1-vaapi for Intel graphics).
+(\* = core, good,  bad, x, gtk, gl, vulkan, pulse, v4l2,  ...), (+ gstreamer1-vaapi for Intel/AMD graphics).
 
 
 ### Starting  and running UxPlay 
@@ -335,13 +335,13 @@ behavior so that when a new client requests a connection, it removes the current
 * In Mirror mode, GStreamer has a choice of **two** methods to play video with its accompanying audio: prior to UxPlay-1.64,
 the video and audio streams were both played as soon as possible after they arrived (the GStreamer "_sync=false_" method), with
 a GStreamer internal clock used to try to keep them synchronized.    **Starting with UxPlay-1.64, the other method
-(GStreamer's "_sync-true_" mode), which uses timestamps in the audio and video streams sent by the client, is the new default**.
+(GStreamer's "_sync=true_" mode), which uses timestamps in the audio and video streams sent by the client, is the new default**.
 On low-decoding-power UxPlay hosts (such as Raspberry Pi 3 models) this will drop video frames that cannot be decoded in time
 to play with the audio, making the video jerky, but still synchronized.
 
 The older method which does not drop late video frames
 worked well on more powerful systems, and is still available with the  UxPlay option "`-vsync no`"; this method  is adapted
-to "live streaming", and may be better when Using UxPlay as a second monitor for a Mac computer, for example, while the new default
+to "live streaming", and may be better when using UxPlay as a second monitor for a Mac computer, for example, while the new default
 timestamp-based method is best for watching a video, to keep lip movements and voices synchronized.   (Without use of timestamps,
 video will eventually lag behind audio if it cannot be decoded fast enough: hardware-accelerated video-decoding helped to prevent this
 previously when timestamps were not being used.)
@@ -379,7 +379,7 @@ See [Usage](#usage) for more run-time options.
 ### **Special instructions for Raspberry Pi (tested on R Pi 4 model B 8GB and  R Pi 3 model B+)**:
 
 * If you use the software-only (h264) video-decoding UxPlay option `-avdec`, it now works
-better that earlier, with the new default timestamp-based synchronization to keep audio and video synchronized.
+better than earlier, with the new default timestamp-based synchronization to keep audio and video synchronized.
 
 * For best performance, the Raspberry Pi needs the GStreamer Video4linux2 plugin  to use
 its Broadcom GPU hardware for decoding h264 video.   This needs the bcm2835_codec kernel module
@@ -444,7 +444,7 @@ used in the macOS builds, so they can be uninstalled after building uxplay, if y
 
 *  If you use Homebrew: `brew install libplist openssl@3`
 
-* if you use MacPorts: `sudo port install plist-devel openssl3`
+* if you use MacPorts: `sudo port install libplist-devel openssl3`
 
 Otherwise, build libplist and openssl from source: see instructions near the  end of this README;
 requires development tools (autoconf, automake, libtool, _etc._) to be installed.
@@ -476,7 +476,12 @@ their location (Homebrew does not supply a complete GStreamer, but seems to have
 
 Finally, build and install uxplay: open a terminal and change into the UxPlay source directory
 ("UxPlay-master" for zipfile downloads, "UxPlay" for "git clone" downloads) and build/install with
-"cmake . ; make ; sudo make install " (same as for Linux).  
+"cmake . ; make ; sudo make install " (same as for Linux).
+
+   * Running UxPlay while checking for GStreamer warnings (do this with "export GST_DEBUG=2" before runnng UxPlay) reveals
+     that with the default (since UxPlay 1.64) use of timestamps for video synchonization, many video frames are being dropped
+     (only on macOS), perhaps due to another error (about videometa) that shows up in the GStreamer warnings.   **Recommendation:
+     use the new UxPlay "no timestamp" option "`-vsync no`"** (you can add a line "vsync no" in the uxplayrc configuration file).
 
    * On macOS with this installation of GStreamer, the only videosinks available seem to be glimagesink (default choice made by
      autovideosink) and osxvideosink.   The window title does not show the Airplay server name, but the window is visible to
@@ -617,7 +622,7 @@ using UxPlay as a second monitor for a mac computer, or monitoring a webcam; wit
    immediately.  _This might in principle be mitigated by using the `-al` audio latency setting to change the latency (default 0.25 secs)
    that the server reports to the client, but at present changing this does not seem to have any effect_.
 
-**-async no**.   This is the still the default behavior in Audio-only mode, but this option may be useful as a command-line option to switch of a
+**-async no**.   This is the still the default behavior in Audio-only mode, but this option may be useful as a command-line option to switch off a
 `-async` option set in a "uxplayrc" configuration file.
 
 **-s wxh** (e.g. -s 1920x1080 , which is the default ) sets the display resolution (width and height,
@@ -882,7 +887,7 @@ ports: **three** are required (the third one receives the audio data).
 **Raspberry Pi** devices work best with hardware GPU h264 video decoding if the Video4Linux2 plugin in  GStreamer v1.20.x or earlier has
 been patched (see the UxPlay [Wiki](https://github.com/FDH2/UxPlay/wiki/Gstreamer-Video4Linux2-plugin-patches) for patches).
 This is fixed in  GStreamer-1.22, and by backport patches from this in distributions such as Raspberry Pi OS (Bullseye): **use option `-bt709`
-with the GStreamer-1.18.4 from Raspberry Pi OS**..
+with the GStreamer-1.18.4 from Raspberry Pi OS**.
 This also needs the bcm2835-codec kernel module that is not in the standard Linux kernel (it is available in Raspberry Pi OS, Ubuntu and Manjaro).
 
 * **If this kernel module is not available in your Raspberry Pi operating system, or if GStreamer < 1.22 is not patched, use option `-avdec`
diff --git a/README.txt b/README.txt
index 11e51d2..feb07ac 100644
--- a/README.txt
+++ b/README.txt
@@ -325,18 +325,19 @@ installed, depending on how your audio is set up.
 -   **Red Hat, or clones like CentOS (now continued as Rocky Linux or
     Alma Linux):** (sudo dnf install, or sudo yum install)
     gstreamer1-libav gstreamer1-plugins-bad-free (+ gstreamer1-vaapi for
-    intel graphics). *You may need to get some of them (in particular
-    gstreamer1-libav) from [rpmfusion.org](https://rpmfusion.org) (which
-    provides packages including plugins that RedHat does not ship for
-    license reasons). \[In recent **Fedora**, the libav plugin package
-    is renamed to "gstreamer1-plugin-libav", which now needs the RPM
-    Fusion package ffmpeg-libs for the patent-encumbered code which
-    RedHat does not provide: check with "`rpm -qi ffmpeg-libs`" that it
-    lists "Packager" as RPM Fusion; if this is not installed, uxplay
-    will fail to start, with error: **no element "avdec_aac"** \]*.
+    Intel/AMD graphics). *You may need to get some of them (in
+    particular gstreamer1-libav) from
+    [rpmfusion.org](https://rpmfusion.org) (which provides packages
+    including plugins that RedHat does not ship for license reasons).
+    \[In recent **Fedora**, the libav plugin package is renamed to
+    "gstreamer1-plugin-libav", which now needs the RPM Fusion package
+    ffmpeg-libs for the patent-encumbered code which RedHat does not
+    provide: check with "`rpm -qi ffmpeg-libs`" that it lists "Packager"
+    as RPM Fusion; if this is not installed, uxplay will fail to start,
+    with error: **no element "avdec_aac"** \]*.
 
 -   **OpenSUSE:** (sudo zypper install) gstreamer-plugins-libav
-    gstreamer-plugins-bad (+ gstreamer-plugins-vaapi for Intel
+    gstreamer-plugins-bad (+ gstreamer-plugins-vaapi for Intel/AMD
     graphics). *In some cases, you may need to use gstreamer or libav\*
     packages for OpenSUSE from
     [Packman](https://ftp.gwdg.de/pub/linux/misc/packman/suse/)
@@ -347,12 +348,12 @@ installed, depending on how your audio is set up.
     Packman).*
 
 -   **Arch Linux** (sudo pacman -Syu) gst-plugins-good gst-plugins-bad
-    gst-libav (+ gstreamer-vaapi for Intel graphics).
+    gst-libav (+ gstreamer-vaapi for Intel/AMD graphics).
 
 -   **FreeBSD:** (sudo pkg install) gstreamer1-libav,
     gstreamer1-plugins, gstreamer1-plugins-\* (\* = core, good, bad, x,
-    gtk, gl, vulkan, pulse, v4l2, ...), (+ gstreamer1-vaapi for Intel
-    graphics).
+    gtk, gl, vulkan, pulse, v4l2, ...), (+ gstreamer1-vaapi for
+    Intel/AMD graphics).
 
 ### Starting and running UxPlay
 
@@ -392,7 +393,7 @@ below for help with this or other problems.
     and audio streams were both played as soon as possible after they
     arrived (the GStreamer "*sync=false*" method), with a GStreamer
     internal clock used to try to keep them synchronized. **Starting
-    with UxPlay-1.64, the other method (GStreamer's "*sync-true*" mode),
+    with UxPlay-1.64, the other method (GStreamer's "*sync=true*" mode),
     which uses timestamps in the audio and video streams sent by the
     client, is the new default**. On low-decoding-power UxPlay hosts
     (such as Raspberry Pi 3 models) this will drop video frames that
@@ -402,7 +403,7 @@ below for help with this or other problems.
 The older method which does not drop late video frames worked well on
 more powerful systems, and is still available with the UxPlay option
 "`-vsync no`"; this method is adapted to "live streaming", and may be
-better when Using UxPlay as a second monitor for a Mac computer, for
+better when using UxPlay as a second monitor for a Mac computer, for
 example, while the new default timestamp-based method is best for
 watching a video, to keep lip movements and voices synchronized.
 (Without use of timestamps, video will eventually lag behind audio if it
@@ -449,7 +450,7 @@ options.
 ### **Special instructions for Raspberry Pi (tested on R Pi 4 model B 8GB and R Pi 3 model B+)**:
 
 -   If you use the software-only (h264) video-decoding UxPlay option
-    `-avdec`, it now works better that earlier, with the new default
+    `-avdec`, it now works better than earlier, with the new default
     timestamp-based synchronization to keep audio and video
     synchronized.
 
@@ -539,7 +540,7 @@ uninstalled after building uxplay, if you wish.
 
 -   If you use Homebrew: `brew install libplist openssl@3`
 
--   if you use MacPorts: `sudo port install plist-devel openssl3`
+-   if you use MacPorts: `sudo port install libplist-devel openssl3`
 
 Otherwise, build libplist and openssl from source: see instructions near
 the end of this README; requires development tools (autoconf, automake,
@@ -585,6 +586,15 @@ UxPlay source directory ("UxPlay-master" for zipfile downloads, "UxPlay"
 for "git clone" downloads) and build/install with "cmake . ; make ; sudo
 make install" (same as for Linux).
 
+-   Running UxPlay while checking for GStreamer warnings (do this with
+    "export GST_DEBUG=2" before runnng UxPlay) reveals that with the
+    default (since UxPlay 1.64) use of timestamps for video
+    synchonization, many video frames are being dropped (only on macOS),
+    perhaps due to another error (about videometa) that shows up in the
+    GStreamer warnings. **Recommendation: use the new UxPlay "no
+    timestamp" option "`-vsync no`"** (you can add a line "vsync no" in
+    the uxplayrc configuration file).
+
 -   On macOS with this installation of GStreamer, the only videosinks
     available seem to be glimagesink (default choice made by
     autovideosink) and osxvideosink. The window title does not show the
@@ -770,7 +780,7 @@ changing this does not seem to have any effect*.
 
 **-async no**. This is the still the default behavior in Audio-only
 mode, but this option may be useful as a command-line option to switch
-of a `-async` option set in a "uxplayrc" configuration file.
+off a `-async` option set in a "uxplayrc" configuration file.
 
 **-s wxh** (e.g. -s 1920x1080 , which is the default ) sets the display
 resolution (width and height, in pixels). (This may be a request made to
@@ -1099,7 +1109,7 @@ patched (see the UxPlay
 [Wiki](https://github.com/FDH2/UxPlay/wiki/Gstreamer-Video4Linux2-plugin-patches)
 for patches). This is fixed in GStreamer-1.22, and by backport patches
 from this in distributions such as Raspberry Pi OS (Bullseye): **use
-option `-bt709` with the GStreamer-1.18.4 from Raspberry Pi OS**.. This
+option `-bt709` with the GStreamer-1.18.4 from Raspberry Pi OS**. This
 also needs the bcm2835-codec kernel module that is not in the standard
 Linux kernel (it is available in Raspberry Pi OS, Ubuntu and Manjaro).
 
diff --git a/renderers/video_renderer_gstreamer.c b/renderers/video_renderer_gstreamer.c
index d348457..e8521e4 100644
--- a/renderers/video_renderer_gstreamer.c
+++ b/renderers/video_renderer_gstreamer.c
@@ -328,7 +328,8 @@ gboolean gstreamer_pipeline_bus_callback(GstBus *bus, GstMessage *message, gpoin
                      "*** If you are letting the default autovideosink select the videosink,\n"
                      "*** GStreamer may be trying to use non-functional hardware h264 video decoding.\n"
                      "*** Try using option -avdec to force software decoding or use -vs <videosink>\n"
-                     "*** to select a videosink of your choice (see \"man uxplay\")");
+                     "*** to select a videosink of your choice (see \"man uxplay\").\n"
+                     "*** Raspberry Pi OS with GStreamer-1.18.4 needs \"-bt709\" uxplay option");
         }
 	g_error_free (err);
         g_free (debug);