Many people have asked us about how to run the videos we’ve demonstrated in the OppiaMobile app on standard mobile phones (not Android smartphones), so this afternoon I had a go at converting the Basic Skills video from Global Health Media Project to run on my old Nokia 6230i (I’m not sure exactly how old this phone is as I got it second hand over 6 years ago). The original low-res version I downloaded from the GHMP website was 33Mb, which is too large to fit on the 32Mb MMC card my phone has, but with a bit of conversion I was able to get this down to just over 5Mb and still be good enough quality to watch on the small screen. For those interested the full technical details of how I converted the videos is below. If you’d like to download the final 5Mb version you can get it here.
Here’s a video of the video running on my Nokia, I’ve also show the basic skills video running on the HTC sensation – just to give a comparison with screen sizes and video/audio quality:
There are lots of reasons why we’ve focused on using Android phones for OppiaMobile – but I’ll leave them for another posting.
The technical details for converting the videos:
For my first attempts at converting the videos I used WinFF (note that I use Ubuntu on my desktop so all the details below is specific to this OS), this converted the videos fine and they played well on my laptop, but when I copied over to my phone I wasn’t getting any sound. Turns out that my phone doesn’t support the AAC audio encoding format, but AMR encoding. To get WinFF or other video conversion tools to process the video with AMR as the audio encoding, I needed to compile ffmpeg with the opencore-amr library. Follow these instructions to do this on your machine.
I then also found this tool for converting videos: Mobile Media Convertor. My first attempts weren’t too successful, I kept getting the error message “Error while opening encoder for output stream #0:1 – maybe incorrect parameters such as bit_rate, rate, width or height” then when I finally got it to convert it still didn’t play on my mobile. Finally I got it figured out and the settings I needed to use in mobile media convertor were:
Audio Frequency: 8000
Audio channels: 1
Video Size: 176:144
Audio Codec: libopencore_amrnb
To set these, press the ‘advanced’ button after selecting the ‘Mobile phone – 3GP video’ conversion option.
Using these settings (almost 6 minute) video was down to 5.3Mb – the quality isn’t great when viewing full screen on my laptop – but it’s perfectly fine for my Nokia phone.