README update about HEVC/4K decoding on R Pi

README.html

@@ -218,13 +218,18 @@ <h1 id="detailed-description-of-uxplay">Detailed description of
 distributions (Ubuntu, Manjaro) available with Raspberry Pi Imager.
 <em>(For GStreamer &lt; 1.22, see the <a
 href="https://github.com/FDH2/UxPlay/wiki/Gstreamer-Video4Linux2-plugin-patches">UxPlay
-Wiki</a>)</em>.</p></li>
-<li><p><strong>(New): Support for h265 (HEVC) hardware decoding on
-Raspberry Pi (Pi 4 model B and Pi 5)</strong></p>
-<p>Support is present, but so far satisfactory results have not been
-obtained. Pi model 5 only provides hardware-accelerated (GPU) decoding
-for h265 video, but not H264, as its CPU is powerful enough for
-satisfactory software H264 decoding</p></li>
+Wiki</a>)</em>. Pi model 5 has no support for hardware H264 decoding, as
+its CPU is powerful enough for satisfactory software H264
+decoding</p></li>
+<li><p>** Support for h265 (HEVC) hardware decoding on Raspberry Pi (Pi
+4 model B and Pi 5)**</p>
+<p>These Raspberry Pi models have a dedicated HEVC decoding block (not
+the GPU), with a driver “rpivid” which is not yet in the mainline Linux
+kernel (but is planned to be there in future). Unfortunately it produces
+decoded video in a non-standard pixel format (NC30 or “SAND”) which will
+not be supported by GStreamer until the driver is in the mainline
+kernel; without this support, UxPlay support for HEVC hardware decoding
+on Raspberry Pi will not work.</p></li>
 </ul>
 <h3 id="note-to-packagers">Note to packagers:</h3>
 <p>UxPlay’s GPLv3 license does not have an added “GPL exception”
@@ -636,14 +641,17 @@ <h3 id="starting-and-running-uxplay">Starting and running UxPlay</h3>
 “<code>-vd omxh264dec</code>”), but this is broken by Pi 4 Model B
 firmware. OMX support was removed from Raspberry Pi OS (Bullseye), but
 is present in Buster.</p></li>
-<li><p><strong>H265 (4K)</strong> video is supported with hardware
-decoding by the Broadcom GPU on Raspberry Pi 5 models, as well as on
-Raspberry Pi 4 model B. <strong>While GStreamer seem to make use of this
-hardware decoding, satisfactory rendering speed of 4K video by UxPlay on
-these Raspberry Pi models has not yet been acheived.</strong> The option
-“-h265” is required for activating h265 support. A wired ethernet
-connection is preferred in this mode (and may be required by the
-client).</p></li>
+<li><p><strong>H265 (4K)</strong> video is potentially supported by
+hardware decoding on Raspberry Pi 5 models, as well as on Raspberry Pi 4
+model B, using a dedicated HEVC decoding block, but the “rpivid” kernel
+driver for this it not yet supported by GStreamer (this driver decodes
+video into a non-standard format that cannot be supported by GStreamer
+until the driver is in the mainline Linux kernel). Raspberry Pi provides
+a version of ffmpeg that can use that format, but at present UxPlay
+cannot use this. The best solution would be for the driver to be
+“upstreamed” to the kernel, allowing GStreamer support. (Software HEVC
+decoding works, but does not seem to give satisfactory results on the
+Pi).</p></li>
 </ul>
 <p>Even with GPU video decoding, some frames may be dropped by the
 lower-power models to keep audio and video synchronized using

README.md

@@ -168,13 +168,17 @@ if not, software decoding is used.
     so far only included in Raspberry Pi OS, and two other  distributions (Ubuntu, Manjaro) available
     with Raspberry Pi Imager. _(For GStreamer < 1.22, see
     the [UxPlay Wiki](https://github.com/FDH2/UxPlay/wiki/Gstreamer-Video4Linux2-plugin-patches))_.
-
-*  **(New): Support for h265 (HEVC) hardware decoding on  Raspberry Pi (Pi  4 model B and Pi 5)**
-
-    Support is present, but so far satisfactory results have not been obtained. 
-    Pi model 5 only provides hardware-accelerated (GPU) decoding for h265 video, but not H264,
+    Pi model 5 has no support for hardware  H264 decoding,
     as its CPU is powerful enough for satisfactory software H264 decoding
 
+*  ** Support for h265 (HEVC) hardware decoding on  Raspberry Pi (Pi  4 model B and Pi 5)**
+
+    These Raspberry Pi models have a dedicated HEVC decoding block (not the GPU), with a driver
+    "rpivid" which is not yet in the mainline Linux kernel (but is planned to be there in future).  Unfortunately
+    it produces decoded video in a non-standard pixel format (NC30 or "SAND") which will not be supported
+    by GStreamer until the driver is in the mainline kernel; without this support, UxPlay support for HEVC
+    hardware decoding on Raspberry Pi will not work.
+
 ### Note to packagers:
 
 UxPlay's GPLv3 license does not have an added
@@ -506,10 +510,13 @@ See [Usage](#usage) for more run-time options.
   (use option "`-vd omxh264dec`"), but this is broken by Pi 4 Model B firmware.  OMX support was removed from
   Raspberry Pi OS (Bullseye),  but is present in Buster.
 
-* **H265 (4K)** video is supported with hardware decoding by the Broadcom GPU on Raspberry Pi 5 models, as well as
-  on Raspberry Pi 4 model B.   **While GStreamer seem to make use of this hardware decoding, satisfactory rendering speed of
-  4K video by UxPlay on these Raspberry Pi models has not yet been acheived.**  The option "-h265" is required for activating h265 support.
-  A wired ethernet connection is preferred in this mode (and may be required by the client).
+* **H265 (4K)** video is potentially supported by hardware decoding on Raspberry Pi 5 models, as well as
+  on Raspberry Pi 4 model B, using a dedicated HEVC decoding block, but the  "rpivid" kernel driver for this
+  it not yet supported by GStreamer (this driver decodes video into a non-standard format that cannot be supported
+  by GStreamer until the driver is in the mainline Linux kernel).  Raspberry Pi provides a version of ffmpeg that
+  can use that format, but at present UxPlay cannot use this.   The best solution would be for the driver to be
+  "upstreamed" to the kernel, allowing GStreamer support.   (Software HEVC decoding works, but does not seem to
+  give satisfactory results on the Pi).
 
 Even with GPU video decoding, some frames may be dropped by the lower-power models  to keep audio and video synchronized
 using timestamps.   In Legacy Raspberry Pi OS (Bullseye), raspi-config "Performance Options" allows specifying how much memory

README.txt

@@ -212,14 +212,19 @@ used.
     available with Raspberry Pi Imager. *(For GStreamer \< 1.22, see the
     [UxPlay
     Wiki](https://github.com/FDH2/UxPlay/wiki/Gstreamer-Video4Linux2-plugin-patches))*.
+    Pi model 5 has no support for hardware H264 decoding, as its CPU is
+    powerful enough for satisfactory software H264 decoding
 
--   **(New): Support for h265 (HEVC) hardware decoding on Raspberry Pi
-    (Pi 4 model B and Pi 5)**
+-   \*\* Support for h265 (HEVC) hardware decoding on Raspberry Pi (Pi 4
+    model B and Pi 5)\*\*
 
-    Support is present, but so far satisfactory results have not been
-    obtained. Pi model 5 only provides hardware-accelerated (GPU)
-    decoding for h265 video, but not H264, as its CPU is powerful enough
-    for satisfactory software H264 decoding
+    These Raspberry Pi models have a dedicated HEVC decoding block (not
+    the GPU), with a driver "rpivid" which is not yet in the mainline
+    Linux kernel (but is planned to be there in future). Unfortunately
+    it produces decoded video in a non-standard pixel format (NC30 or
+    "SAND") which will not be supported by GStreamer until the driver is
+    in the mainline kernel; without this support, UxPlay support for
+    HEVC hardware decoding on Raspberry Pi will not work.
 
 ### Note to packagers:
 
@@ -632,14 +637,17 @@ See [Usage](#usage) for more run-time options.
     this is broken by Pi 4 Model B firmware. OMX support was removed
     from Raspberry Pi OS (Bullseye), but is present in Buster.
 
--   **H265 (4K)** video is supported with hardware decoding by the
-    Broadcom GPU on Raspberry Pi 5 models, as well as on Raspberry Pi 4
-    model B. **While GStreamer seem to make use of this hardware
-    decoding, satisfactory rendering speed of 4K video by UxPlay on
-    these Raspberry Pi models has not yet been acheived.** The option
-    "-h265" is required for activating h265 support. A wired ethernet
-    connection is preferred in this mode (and may be required by the
-    client).
+-   **H265 (4K)** video is potentially supported by hardware decoding on
+    Raspberry Pi 5 models, as well as on Raspberry Pi 4 model B, using a
+    dedicated HEVC decoding block, but the "rpivid" kernel driver for
+    this it not yet supported by GStreamer (this driver decodes video
+    into a non-standard format that cannot be supported by GStreamer
+    until the driver is in the mainline Linux kernel). Raspberry Pi
+    provides a version of ffmpeg that can use that format, but at
+    present UxPlay cannot use this. The best solution would be for the
+    driver to be "upstreamed" to the kernel, allowing GStreamer support.
+    (Software HEVC decoding works, but does not seem to give
+    satisfactory results on the Pi).
 
 Even with GPU video decoding, some frames may be dropped by the
 lower-power models to keep audio and video synchronized using