Sunday, April 6, 2008

Mobile Optimized Files, Audio Types & Display Messages

Click Here to see a walkthrough demo of Nokia Podcasting.

Some podcasters are wondering why the "Content may not play on your device" warning is popping up for normal audio files. Our development team gives the answers:

The determining factor for whether or not the podcasting app displays this warning is actually not the file extension, but the mime type that is provided in the enclosure tag. (We only use the file extension for display on the UI.)

Whatever content you use, just make sure you provide a MIME type that is supported in our phones.

A complete list of Browser MIME types in Nokia GSM Devices can be found here: Link

(look in Chapter 7 for S60 3rd edition).

One exception to this is MP4 (video and audio mp4 content). Because MP4 is a container format and we have no idea if the content within the MP4 container will be played correctly, for audio/mp4 or video/mp4 content we display the warning "might not display properly" and don't auto-download these episodes.

If your audio show is in aac format, the best MIME type would be "audio/aac" - that doesn't display any warnings.

And when creating an audio podcast specifically for a mobile audience, I would recommend to use AAC (or better yet, eAAC+) because of the smaller filesize and/or better quality at the same file size, compared to MP3.

The Nokia Music Manager from the Nokia PC Suite (download here) is able to convert your mp3 files into eAAC+.

NOTE: If you want your video podcast optimized for mobile (size, playback compatibility and no warning), use the format 3gp. (Most compatible devices are able to play frames per second (fps), newer devices like N95, N81, N93, etc can play 30 fps)

OK....I realize you shouldnt need a workaround, but if you know your video format is compatible with the Nokia devices and you want to make sure the warning message doesnt come up, here is a way to "cheat".

If you have an MP4 video file in a format that for sure plays on our devices, you can set file extension to ".mpeg" and the mime type in the enclosure to "video/3gpp" to avoid that warning message and to allow auto-downloads ;) ... a bit hacky, but works nicely. Please note that the .mpeg extension is important, too.


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