Raspberry Pi Forums

Posted: **Mon Apr 06, 2015 9:44 pm**

Recently got my hands on a raspberry pi 2, and started looking (again) at mpeg2 software decoding - a revisit of an old 2012 thread: http://www.raspberrypi.org/forums/viewt ... =29&t=5641

Test equipment
PI 2: Ordered as a kit from pihut
PI 1: 2x Original Model B's from 2012

Common equipment:
Memory Card : 8GB Sandisk Ultra Class 10 MicroSD
Power Supply: kit supplied 5V 2A
OS: '2015-02-16-raspbian-wheezy.img' with 'apt-get update' and 'apt-get upgrade' ran.
SW: 'mpeg2test' using libmpeg2 0.5.1 + idct ARM optimizations from rockbox, GIT repo https://github.com/linuxstb/pidvbip.git, commit f77258dbda40329cd17f0361ff341cba00644f7a
Test vectors: mpeg2_samples_m2v.zip from original thread.

Note, I had to make a small Makefile change, adding '-I/opt/vc/include/interface/vmcs_host/linux' to INCLUDES line.

Results:

Code: Select all

PI.1 vs PI.2            Source FPS	PI-1 FPS	P1.1 %		PI-2 FPS	PI-2 %
bbc1_dvbt_30secs.m2v    25.00       31.59       126.36%     61.74       246.96%
bbc1s_dvbs_30secs.m2v   25.00	    27.12       108.48%     52.61       210.44%
centaur_2.m2v           29.97       31.33       104.54%     63.88       213.15%
dave_dvbt_30secs.m2v    25.00       48.84       195.36%     94.58       378.32%
hst_2.m2v               29.97       27.64        92.23%     54.31       181.21%

Conclusion is the PI-2 for single threaded mpeg2 decoding is twice as fast as the PI-1, so it should be possible to decode mpeg2 on the PI-2 ARM CPUs (plus headroom for audio decoding) without the 'MPEG-2 license key' that enables decoding on the GPU. - I also got same results on both original model B's...

Footnote: IANAL (I Am Not A Lawyer) - This is proof-of-concept work and take no responsibility for the state of licensing a MPEG2 software decoder in your country or jurisdiction.

Posted: **Thu Apr 23, 2015 6:00 am**

This sounds really interesting.
How can we plug it to work with XBMC?

Posted: **Fri Apr 24, 2015 7:39 am**

So, I disabled the hardware acceleration on a Xbian Kodi and the dvb tv source played normaly the only thing was the deinterlacing effect didn't work.
I am wondering how to disabled hardware acceleration for a certain codec in kodi.

Posted: **Thu Apr 30, 2015 7:13 pm**

Thanks that interesting info that CPU MPEG2 decoding works minus the interlacing ... and applogies, not had time yet to look into this further

My plan was to use Kodi (formally XBMC) with the live tv plugin streaming recordings and live tv from a myth backend hooked up to a freesat feed.

A sensible guess from playing with broadcom GPU features via OpenMax IL: I think the issue is the HW acceleration on the broadcom GPU not only decodes MPEG2 but also does the De-interlacing - so the video chain needs a little tweaking to add software De-interlacing before sending the video of to the broadcom GPU for display.

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PI 2 mpeg2 software decoding revisited

PI 2 mpeg2 software decoding revisited

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Re: PI 2 mpeg2 software decoding revisited