Ogg-support 1.1.1: Performance

After almost two years there’s a new version of the Ogg Support in the Fremantle Extras.

The decoder code has changed completely. Where the old one used libvorbis and vorbisdec from the GStreamer base plugins, the new one uses libav (formerly FFmpeg) and gst-av from Felipe Contreras. The impact on performance should be significant because the vorbis decoder in libav is more efficient on the n900 than the libvorbis and Felipe’s gst-av also outperforms the vorbisdec.

Thanks to Felipe for doing all the hard work. I’ve just been updating the version numbers of the dependencies and tracking the bugzilla for the known issues and fixes :)

Command line sharing plugin in extras-devel

I reflashed my device and the biggest annoyance after restoring the backup was recompiling the sharing-cli plugin as it was not in any repository. Now it is.

It has been working for me for several months without issues, although I’ve been sharing only medium size images over a decent connection. It might not succeed in sharing videos over GPRS.

For hints about the usage, see the previous post.

Command line sharing plugin for n900

Thomas Perl made a proposal for creating a command line sharing plugin for the n900. I had already planned to implement something like that so I joined the project.

I pushed the first “proof-of-concept” quality implementation to the GIT a month ago. I’ve been using it with the Irssi script (in the scripts directory) to get http URLs with meta information to IRC. The Irssi script needs to be modified to match the directories and IRC servers in use and both the script and the sharing plugin are still missing most of the error checking and extra functionality. Nevertheless, they’ve worked for me for the past weeks.

For the sharing plugin I’ve given something like the following command line:


scp %s kulve@foo.bar.fi:~/photos_incoming/%s

There’s two times the %s as the local temporary file name doesn’t match the actual file name to be copied. And that assumes the SSH keys have been exchanged so that no passwords will be asked.

The Irssi script polls the incoming directory for new images. For each new file, it moves the file to public WWW tree, gets the meta information with exiftool and prints something like this to the specified IRC channel:


Title: Description [tags] (GPS coordinates) http://foo.bar.fi/~kulve/imagename.jpg

I modified the Irssi script a bit before pushing it to the GIT, so no guarantees it works. And that’s my first Irssi script ever, so it may do something odd ;)

There’s no debian packages yet as neither the script nor the plugin have been tested properly. Comments, testing and patches are welcome.

n900 Battery Duration: Ogg vs. MP3

There have always been complaints about Ogg being more of a battery hog on the Nokia tablets compared to Nokia optimized MP3. I decided to measure the difference.

All tests were run on a preproduction n900 device that Nokia distributed at the Maemo Summit. The software is the Maemo5 41-10 release which was already installed in the device. I installed Ogg Support, gst-av, ffmpeg and OpenSSH. Otherwise the device is the default 41-10 release. WLAN connection was configured but not activated during the tests. A SIM card was in place only in the SIM idle test.

Before every test I charged the device, disconnected the charger once I noticed the green led, and rebooted the device. After the boot I started a simple script in the xterm. The script logged current time to a file, run “sync” command and slept 60 seconds after which it started the loop again.

Idle tests

I run two idle tests between the libvorbis and ffvorbis tests but I’ll introduce the idle results first.

First idle test was a generally idle device. I.e. it did have the default processes running but I didn’t start anything, except my logging script. During the test I did check a couple of times if the device was still on. The battery lasted for 93.8 hours.

According to Igor Stoppa, there’s a cellmo sw bug that makes current higher without a SIM card. Therefore I rerun the idle test with a SIM card inserted. During the test I received two phone calls which I hung up, I received two SMS messages and wrote one. At one point the notification led was blinking for 45 mins. The battery laster for 93.6 hours.

There’s probably a few hour error margin on those tests, so basically the battery lasted roughly a bit over 90 hours in both tests.

Powertop shows that after 60 seconds of showing the xterm with display blanked, the CPU is mostly in the highest C4 sleep state:


C# Ratio Avg/dura Frequency Ratio
C0 0.3% 600 MHz 0.0%
C1 0.0% 550 MHz 0.0%
C2 0.1% 1.1ms 500 MHz 0.0%
C3 0.2% 15.2ms 250 MHz 100.0%
C4 99.5% 2297.0ms    

Ogg vs. MP3

Now that we know how long the device will last when idle we can move to the actual results.

I run two sets of tests. First one was with the Ogg Support 1.0.5 from Extras and the second one with Felipe’s gst-av (2009-09-25) which is using vorbis decoder from FFmpeg (2009-09-07). I repeated both tests three times, running every other test with MP3 and every other with Ogg.

After restarting the device with a fully charged battery I started the logging script in the xterm, started the File Manager and clicked on the MP3 or Ogg file which then started playing that single file in a loop in the Media Player. Both files were encoded with variable bitrate 192kbps settings. Volume of the device was set to minimum and no headphones were connected.

This is what powertop shows while playing MP3 in Media Player compared to libvorbis:


MP3 libvorbis
C# Ratio Avg/dura Frequency Ratio
C0 37.9% 600 MHz 3.1%
C1 0.0% 0.2ms 550 MHz 1.1%
C2 7.0% 3.0ms 500 MHz 17.5%
C3 55.1% 8.0ms 250 MHz 78.3%
C4 0.0%    
C# Ratio Avg/dura Frequency Ratio
C0 70.1% 600 MHz 18.2%
C1 0.0% 0.1ms 550 MHz 0.0%
C2 4.7% 2.7ms 500 MHz 28.8%
C3 25.1% 7.8ms 250 MHz 52.9%
C4 0.0%    

Clearly while using libvorbis the CPU spents more time in lower sleep state and running with higher frequency. The following graph shows how this affects the battery. The battery lasts around 18 hours while playing MP3 but only around 11 hours while playing Ogg.

Battery duration: MP3 vs. libvorbis

Next numbers are with ffvorbis instead of libvorbis. Powertop shows that while using ffvorbis the time spent in different sleep states matches quite closely to the ones of MP3 usage:


MP3 ffvorbis
C# Ratio Avg/dura Frequency Ratio
C0 37.9% 600 MHz 3.1%
C1 0.0% 0.2ms 550 MHz 1.1%
C2 7.0% 3.0ms 500 MHz 17.5%
C3 55.1% 8.0ms 250 MHz 78.3%
C4 0.0%    
C# Ratio Avg/dura Frequency Ratio
C0 38.4% 600 MHz 2.1%
C1 0.0% 0.1ms 550 MHz 0.0%
C2 5.7% 3.1ms 500 MHz 13.2%
C3 55.9% 8.3ms 250 MHz 84.6%
C4 0.0%    

The similarity of the powertop numbers can be seen in the battery duration as well:

Battery duration: MP3 vs. ffvorbis

The average battery duration while using ffvorbis was slightly better than while using MP3 but probably well within the error margins. So basically they are equal when battery duration is concerned.

It’s interesting to see how the situation changes in a year, will Nokia make better optimizations to their MP3 decoder than the community to the FFmpeg. These tests were run in a preproduction device with a pre-sales software. I’m sure the overall power management of the device will get (even?) better in the future software releases.

Addition (2009-11-17):

When using the speakers the n900 runs some “speaker protection algorithms” that take extra power. I repeated the ffvorbis test case with Nokia’s headset and here are the results:

Battery duration: ffvorbis with headphones

On the average the battery duration improved a bit over three hours.

Addition (2009-11-25):

I run the same tests (Ogg Support 1.0.5, no headset) for Flac:

Battery duration: libflac

n900 with a pre-sales w41-10 software can run Flac roughly 1.5 hours longer than MP3.

Wishlist for N900 ogg-support

Time to switch to a Linux phone and time to start preparing ogg-support for N900/Fremantle.

Hopefully everything will be easier to get working with the N900 since at least the closed source Metalayer Crawler is replaced with open source Tracker.

I would like to hear if there’s anything special people would like to get with ogg-support. Support for oggs in the built-in media player with tags is of course the first goal but is there something else that is a must? Theora? Flac?

Thanks.