still cannot find after clean, even re-install all the gstreamer plugins and ffmpeg, still unable to see avdec_264 element detected. Also clean the .cache which advised by Danell, thank you.
$ sudo apt install ffmpeg
Reading package lists… Done
Building dependency tree
Reading state information… Done
The following packages were automatically installed and are no longer required:
apg cheese-common evince-common gir1.2-rb-3.0 gir1.2-totem-1.0 gir1.2-totemplparser-1.0 gnome-control-center-faces
gnome-online-accounts grilo-plugins-0.3-base libcolord-gtk1 libdjvulibre-text libdjvulibre21 libdmapsharing-3.0-2
libevdocument3-4 libgoa-backend-1.0-1 libgom-1.0-0 libgpod-common libgpod4 libgrilo-0.3-0 libgsound0 libgupnp-av-1.0-2
libgupnp-dlna-2.0-3 libkpathsea6 liblua5.3-0 libmediaart-2.0-0 librhythmbox-core10 librygel-core-2.6-2 librygel-db-2.6-2
librygel-renderer-2.6-2 librygel-server-2.6-2 libsgutils2-2 libspectre1 libsynctex2 libsysmetrics1 libtotem0
media-player-info mobile-broadband-provider-info network-manager-gnome python3-brlapi python3-louis python3-macaroonbakery
python3-mako python3-markupsafe python3-protobuf python3-pyatspi python3-pymacaroons python3-rfc3339 python3-speechd
rhythmbox-data rygel totem-common xbrlapi
Use ‘sudo apt autoremove’ to remove them.
Suggested packages:
ffmpeg-doc
The following NEW packages will be installed:
ffmpeg
0 upgraded, 1 newly installed, 0 to remove and 117 not upgraded.
Need to get 1,440 kB of archives.
After this operation, 2,021 kB of additional disk space will be used.
Get:1 Index of /ubuntu-ports focal-updates/universe arm64 ffmpeg arm64 7:4.2.7-0ubuntu0.1 [1,440 kB]
Fetched 1,440 kB in 2s (898 kB/s)
debconf: delaying package configuration, since apt-utils is not installed
Selecting previously unselected package ffmpeg.
(Reading database … 163266 files and directories currently installed.)
Preparing to unpack …/ffmpeg_7%3a4.2.7-0ubuntu0.1_arm64.deb …
Unpacking ffmpeg (7:4.2.7-0ubuntu0.1) …
Setting up ffmpeg (7:4.2.7-0ubuntu0.1) …
Processing triggers for man-db (2.9.1-1) …
$ rm .cache/gstreamer-1.0/registry.aarch64.bin
$ gst-inspect-1.0 | grep h264
uvch264: uvch264src: UVC H264 Source
uvch264: uvch264mjpgdemux: UVC H264 MJPG Demuxer
nvvideo4linux2: nvv4l2h264enc: V4L2 H.264 Encoder
videoparsersbad: h264parse: H.264 parser
rtp: rtph264pay: RTP H264 payloader
rtp: rtph264depay: RTP H264 depayloader
typefindfunctions: video/x-h264: h264, x264, 264
cpmusr@pglunvd07:~$ gst-inspect-1.0 avdec_h264
No such element or plugin ‘avdec_h264’
cpmusr@pglunvd07:~$ uname -a
Linux pglunvd07 5.10.104-tegra #1 SMP PREEMPT Wed Aug 10 20:17:07 PDT 2022 aarch64 aarch64 aarch64 GNU/Linux
cpmusr@pglunvd07:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.4 LTS
Release: 20.04
Codename: focal
cpmusr@pglunvd07:~$ dpkg -l ffmpeg
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
++±==============-==================-============-================================================================
ii ffmpeg 7:4.2.7-0ubuntu0.1 arm64 Tools for transcoding, streaming and playing of multimedia files