webm dash encoding... What are the correct ffmpeg parameters?

I'm stumped with encoding videos into a dash compliant format. I'm going from .mp4 to .webm

Firstly, I am running OS X and ffmpeg 2.5.4.

Here's the encoding commands I am using in my test (I got these from here):

ffmpeg -i IMG_0113.mp4 -c:v libvpx-vp9 -s 160x90 -b:v 25k -g 1 -tile-columns 4 -frame-parallel 1 -an -f webm -dash 1 video_160x90_25k.webm ffmpeg -i IMG_0113.mp4 -c:v libvpx-vp9 -s 160x90 -b:v 50k -g 1 -tile-columns 4 -frame-parallel 1 -an -f webm -dash 1 video_160x90_50k.webm ffmpeg -i IMG_0113.mp4 -vn -acodec libvorbis -ab 128k -dash 1 audio_128k.webm ffmpeg -f webm_dash_manifest -i video_160x90_25k.webm -f webm_dash_manifest -i video_160x90_50k.webm -f webm_dash_manifest -i audio_128k.webm -c copy -map 0 -map 1 -map 2 -f webm_dash_manifest -adaptation_sets "id=0,streams=0,1 id=1,streams=2" manifest.mpd

Secondly, the problem is not with my server, as I have downloaded the samples from here, and they work 100% on the dash.js player when served from my local server.

Please could someone out there point me in the right direction? Or provide a sample of the ffmpeg commands used to get the output format correct.

Thanks, Dean.