Difference between revisions of "Video Decoding Performance"

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[http://thedigitallifestyle.com/w/index.php/2012/08/29/what-do-the-mpeg-2-and-vc-1-decoder-options-get-you-on-the-raspberry-pi/ | what-do-the-mpeg-2-and-vc-1-decoder-options-get-you-on-the-raspberry-pi/]
 
[http://thedigitallifestyle.com/w/index.php/2012/08/29/what-do-the-mpeg-2-and-vc-1-decoder-options-get-you-on-the-raspberry-pi/ | what-do-the-mpeg-2-and-vc-1-decoder-options-get-you-on-the-raspberry-pi/]
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[http://www.raspberrypi.org/archives/tag/mpeg-2 http://www.raspberrypi.org/archives/tag/mpeg-2]
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[http://www.engadget.com/2012/08/26/raspberry-pi-mpeg-2-vc-1-licenses-cec-h264/ http://www.engadget.com/2012/08/26/raspberry-pi-mpeg-2-vc-1-licenses-cec-h264/]

Latest revision as of 16:47, 29 August 2012


This page records a number of possible ways to playback or stream video from you RPi.

MPlayer performance

This test requires you have Mplayer installed and an SSH connection Enable_SSH and some kind display connected ideally by HDMI.

sudo apt-get install mplayer

Test Process

  1. SSH into tthe RPi, two connections is optimal.
  2. Execute the MPlayer command given below with the required fps
  3. Use the second SSH terminal to write the output of top to a file
  4. Record the mean CPU% for a range of fps
mplayer -fps 1 tv:// -tv driver=v4l2:device=/dev/video0:width=320:height=240
top -n 20 -b | grep mplayer > 1fps.txt

Data Analysis

the file written by the top typically looks like

 2295 pi    20   0 65892  15m 6812 S   0.0  8.4   0:01.26 mplayer
 2295 pi    20   0 65892  15m 6812 S   3.9  8.4   0:01.38 mplayer
 2295 pi    20   0 65892  15m 6812 S   3.9  8.4   0:01.50 mplayer
...         
etc

Some awk get the average using

$ cat ave.awk
#!/usr/bin/awk -f
# Calculate average, syntax: avg.awk field-number file
BEGIN { field = ARGV[1]; ARGV[1] = "" }
{ sum += $field }
END { print sum / NR }

Average CPU is found using

$ ./ave.awk 9 1fps.txt
$ 3.51

Results

Linux raspberrypi 3.2.27+ #66 PREEMPT Fri Aug 24 23:52:42 BST 2012 armv6l GNU/Linux

PS3eye on Raspian
fps CPU(%) @320x240 CPU(%) @640x480
01 2.665 12.13
02 4.88 19.985
05 11.90 51.735
10 23.425 95.62*
15 35.85 95.39***
20 47.78 95.565*
25 60.86 96.83*
30 72.05 95.065*

*this is the CPU maxed out, the actually achieved frame rate is probably between 5-10Hz.

Hardware Acceleration

From Aug 2012, the RaspberryPi foundation sucessfully negotiated licences for MPEG2 and VC-1 for use in the RPi. This required a firmware upgrade and the user to purchase the license for a small fee RPi Shop .

Hardware acceleration does not affect video capture, only video playback.

| what-do-the-mpeg-2-and-vc-1-decoder-options-get-you-on-the-raspberry-pi/

http://www.raspberrypi.org/archives/tag/mpeg-2

http://www.engadget.com/2012/08/26/raspberry-pi-mpeg-2-vc-1-licenses-cec-h264/