XUELK-AN-006: Video playing on i.MX6UL-based platforms
History[edit | edit source]
|1.0.0||May 2017||First release|
Introduction[edit | edit source]
As known, i.MX6UL SoC is not designed to implement rich complex user interfaces (UI), even though it integrates an LCD controller. However, even simple UIs might require playing some sort of low-resolution videos.
This application note describes some tests that were performed on an AXELULite-based platform to evaluate the capabilities and the performances of the i.MXUL when it comes to playing such videos. The test bed was based on Debian Jessie distribution, as described here.
gstreamer[edit | edit source]
We assume that network interface has been already configured as described on XUELK-AN-002: Running Debian distribution.
Adding gstreamer packages[edit | edit source]
It is possibile to install the complete gstreamer 1.0 suite (easy way to have the richest rfs configuration for gstreamer usage)
root@arm:~# apt-get install gstreamer1.0 Reading package lists... Done Building dependency tree Reading state information... Done ... The following NEW packages will be installed: ... gstreamer1.0-clutter gstreamer1.0-doc gstreamer1.0-fluendo-mp3 gstreamer1.0-gnonlin gstreamer1.0-gnonlin-dbg gstreamer1.0-gnonlin-doc gstreamer1.0-libav gstreamer1.0-libav-dbg gstreamer1.0-nice gstreamer1.0-packagekit gstreamer1.0-plugins-bad gstreamer1.0-plugins-bad-dbg gstreamer1.0-plugins-bad-doc gstreamer1.0-plugins-base gstreamer1.0-plugins-base-apps gstreamer1.0-plugins-base-dbg gstreamer1.0-plugins-base-doc gstreamer1.0-plugins-good gstreamer1.0-plugins-good-dbg gstreamer1.0-plugins-good-doc gstreamer1.0-plugins-ugly gstreamer1.0-plugins-ugly-dbg gstreamer1.0-plugins-ugly-doc ... usb-modeswitch usb-modeswitch-data usbmuxd va-driver-all x11-common x11-utils xkb-data 0 upgraded, 517 newly installed, 0 to remove and 32 not upgraded. Need to get 252 MB of archives. After this operation, 713 MB of additional disk space will be used. Do you want to continue? [Y/n] Y
as it's shown on installation log, apt-get asks for installing 713MB of additional packages. In case you are looking for a reduced space installation, you may need to select the minimum required packages for video decoding.
Tipically, it is enough to install:
gstreamer1.0-tools gstreamer1.0-plugins-base gstreamer1.0-plugins-good gstreamer1.0-plugins-bad gstreamer1.0-plugins-ugly gstreamer1.0-videosink
but required packages are strictly related to the gstreamer pipeline invoked and what kind of video/audio stream want to be decoded.
gstreamer pipeline[edit | edit source]
The pipeline used is the easiest one for decoding a local file on rfs
gst-launch-1.0 -vvv playbin uri=file:///root/<local_filename> video-sink=fbdevsink
Test bed[edit | edit source]
- iMX6UL cpu has 3 scaling frequencies availables requested by cpu load
root@arm:~# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor interactive root@arm:~# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies 198000 396000 528000
- iMX6UL cpu is running at 528MHz when decoding
root@arm:~# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq 528000
- system DRAM is 256MB
- lcd panel is 800x480
Results[edit | edit source]
Use case #1: MPEG4 640x360@24fps[edit | edit source]
- file: BigBuckBunny_640x360.mp4
- video: MPEG-4 video 4:2:0 @ 640x360 resolution
gst-launch-1.0 -vvv playbin uri=file:///root/video/BigBuckBunny_640x360.mp4 video-sink=fbdevsink
- top process shows that cpu is running at 99%
top - 08:24:14 up 1:28, 2 users, load average: 0.19, 0.18, 0.38 Tasks: 60 total, 1 running, 59 sleeping, 0 stopped, 0 zombie %Cpu(s): 98.4 us, 1.3 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.0 hi, 0.3 si, 0.0 st KiB Mem: 247172 total, 244012 used, 3160 free, 30660 buffers KiB Swap: 0 total, 0 used, 0 free. 123020 cached Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 11998 root 20 0 121480 18880 6180 S 99.4 7.6 0:09.77 gst-launch-1.0 11997 root 20 0 2980 1068 756 R 0.7 0.4 0:00.20 top 1 root 20 0 25840 2972 1880 S 0.0 1.2 0:14.17 systemd 2 root 20 0 0 0 0 S 0.0 0.0 0:00.01 kthreadd ...
This is the reasonable maximum video resolution that can be fully decoded in software (this is due to iMX6UL absence of 3D hardware accelerator)
Use case #2: MPEG4 320x180@24fps[edit | edit source]
This use case is similar to the previous one, but the same video file has been scaled to 1/4 the original dimension (0.5 horizontal and 0.5 vertical)
- file: BigBuckBunny_320x180.mp4
- video: MPEG-4 video 4:2:0 @ 320x180 resolution
gst-launch-1.0 -vvv playbin uri=file:///root/video/BigBuckBunny_320x180.mp4 video-sink=fbdevsink
- top process shows that cpu is running at 42%
top - 08:26:59 up 1:31, 2 users, load average: 1.21, 0.68, 0.54 Tasks: 60 total, 1 running, 59 sleeping, 0 stopped, 0 zombie %Cpu(s): 41.1 us, 1.7 sy, 0.0 ni, 57.2 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem: 247172 total, 243736 used, 3436 free, 30796 buffers KiB Swap: 0 total, 0 used, 0 free. 125184 cached Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 12004 root 20 0 121068 17116 6372 S 42.4 6.9 0:10.00 gst-launch-1.0 11997 root 20 0 2980 1068 756 R 0.7 0.4 0:01.29 top 30 root rt 0 0 0 0 S 0.3 0.0 0:03.86 cfinteractive 11610 root 20 0 0 0 0 S 0.3 0.0 0:02.05 kworker/0:0 ...
This can be a more real use case where the cpu is partially devoted to video decoding and can perform the other usual tasks (graphics, user interaction, peripherals controls, etc.) without major impacts.