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remove -rpi option (it was premature to add it)

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fduncanh
2022-03-02 19:47:59 -05:00
parent 23addca4e1
commit c0b4dc4e73
5 changed files with 71 additions and 66 deletions
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README.md
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@@ -76,24 +76,22 @@ Users must do this themselves: see [these instructions](https://gist.github.com/
adapt them as necessary for your GStreamer installation.
This plugin should be used with the `-vd nvdec` (or nvh264dec) and `-vs glimagesink` uxplay options.
* **support for Raspberry Pi** (_work in progress_): the R Pi platform has long been
supported by [RPiPlay](http://github.com/FD-/RPiPlay) using the deprecated 32-bit-only omx (OpenMAX) decoder, now
removed from latest Raspberry Pi OS (Bullseye), leading to user interest in getting UxPlay to work
on the R Pi (at least on model 4). UxPlay can work with software h264 video decoding (option `-avdec`), but without hardware decoding
has unacceptable latency on the Pi. The Video4Linux2 GStreamer plugin v4l2h264dec (from gstreamer1.0-plugins-good) is now the
appropriate choice for accelerated
hardware video decoding by the Broadcom GPU on the Pi. UxPlay options can be used to create GStreamer video pipelines to use
non-VAAPI hardware decoders, and a new UxPlay option `-rpi` creates a pipeline that should be appropriate for the Raspberry Pi,
and when it has worked, it has worked well. However, it usually does not work because of a "caps" mismatch between source and
sink, which could be fixable with GStreamer "know-how" (perhaps involving using the "capssetter" element). The GStreamer
video pipeline is "` (decrypted h264 stream from iOS)! queue ! h264parse ! decodebin ! videoconvert ! autovideosink sync=false`"
and the uxplay options `-vp , -vd, -vc ,-vs` can be used to
replace `h264parse, decodebin, videoconvert, autovideosink` by the user's
choices. (`-rpi` is equivalent
to `-vd v4l2h264dec -vc v4l2convert`). The first frame in the h264 video stream sends the "caps"
details (SPS, PPS) to h264parse. UxPlay users with the R Pi (model 4 recommended) are invited to experiment and report any
successes. (The uxplay `-d` option will display the actual video pipeline being
used, `export GST_DEBUG=2` before running uxplay will display GStreamer errors and warnings.)
* **possible support for Raspberry Pi** (_not working_): the CPU of the Raspberry Pi is not powerful
enough for GStreamer to decode the h264 video stream using software decoding (option `-avdec` ) without unacceptable latency.
The Pi has a Broadcom GPU for accelerated hardware h264 decoding, and in the past this has been
supported by [RPiPlay](https://github.com/FD-/RPiPlay) using the deprecated 32-bit omx (OpenMax) driver. Unfortunately, with the move
to a 64-bit OS, this has been removed from recent Raspberry Pi OS (Bullseye), and there has been user interest in making UxPlay work on the Pi.
The designated replacement for OpenMAX is Video4linux2, and the options that
_should_ work with UxPlay are `-vd v4l2h264dec -vc v4l2convert`, which are from gstreamer1.0-plugins-good.
This has occasionally worked, and when it did, it worked well, with no
appreciable latency. Unfortunately, the v4l2h264dec GStreamer plugin usually fails to match the "caps" (capacities) of the h264
source to the videosink, and h264 hardware decoding fails. It is
not clear whether there is any workaround before an updated v4l2h264dec plugin becomes available. GStreamer-knowledgeable users
who wish to experiment can see if any video pipeline modifications can provide a workaround:
the pipeline is ` (video stream from appsrc) ... ! h264parse ! decodebin ! videoconvert ! autovideosink ... `; the elements h264parse,
decodebin, videoconvert, and autovideosink can respectively be modified with options -vp, -vd, -vc, and -vs. Please report any successes!
(See [this](https://github.com/raspberrypi/firmware/issues/1673), which suggests some workaround involving "capssetter" might be possible;
`export GST_DEBUG=GST_CAPS:5` may be useful in debugging the pipeline.
### Note to packagers: OpenSSL-3.0.0 solves GPL v3 license issues.
@@ -349,12 +347,15 @@ Also: image transforms that had been added to RPiPlay have been ported to UxPlay
**-r {R|L}** 90 degree Right (clockwise) or Left (counter-clockwise)
rotations; these are carried out after any **-f** transforms.
**-vd _decoder_** chooses the GStreamer pipeline's h264 decoder, instead of letting
**-vp _parser_** choses the GStreamer pipeline's h264 parser element, default is h264parse. Using
quotes "..." allows options to be added.
**-vd _decoder_** chooses the GStreamer pipeline's h264 decoder element, instead of letting
decodebin pick it for you. Software decoding is done by avdec_h264; various hardware decoders
include: vaapi264dec, nvdec, nvh264dec, v4l2h264dec (these require that the appropriate hardware is
available). Using quotes "..." allows some parameters to be included with the decoder name.
**-vc _converter_** chooses the GStreamer pipeline's videoconverter, instead of the default
**-vc _converter_** chooses the GStreamer pipeline's videoconverter element, instead of the default
value "videoconvert". When using video4linux hardware decoding by a GPU,`-vc v4l2convert` will also use
the GPU for video conversion. Using quotes "..." allows some parameters to be included with the converter name.