Created attachment 277966 [details]
Screenshot of garbled frames

Using a playbin on iOS to play a webm file, like http://video.webmfiles.org/big-buck-bunny_trailer.webm results in most pixels on the screen being incorrect when running on an actual device.

They change all over the image and some frames seem to have more glitches than others.
If you squint, you can tell what the frame should look like, so some pixels are getting through, but not a lot.

We've tried other webm files and they have the same problem.
Running the above video on the emulator works mostly, but garbles a little towards the end.
Running on a real device is unwatchable.

Other videos don't seem to have any trouble with the emulator, but don't work on the phone either.

Watching videos in h264 works fine everywhere.

The test device is an iphone5s and I believe it's running ios7.0.6

The only things on the console are 
0:01:08.923024000 [335m10720[00m  0x2bc26f8 [33;01mWARN   [00m [00m           osxaudio 
                                          ./gstosxcoreaudioremoteio.c:74:gst_core_audio_get_samples_and_latency_impl:<GstCoreAudio@0x3430848>[00m Failed to get latency: \316\377\377\377

and
 0:00:00.949570000 [335m10720[00m  0x2bc2ba8 [33;01mWARN   [00m [00m        osxaudiosink gstosxaudiosink.c:556:gst_osx_audio_sink_allowed_caps:<osxaudiosink0>[00m This driver does 
                                          not support kAudioDevicePropertyPreferredChannelLayout.

Which don't seem relevant but I'll include them anyway.

I've attached a screenshot: