Audio and MP3 player library questions

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gwideman

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I am looking at the feasibility of using Teensy 3.x with Audio and MP3 libraries as the basis of an audiobook player. (An audiobook player that would be tractable to users who have some cognitive or physical limitations -- hence the interest in a hackable platform to make specific physical UI.)

Top questions:

1) Is this size of file realistic for a Teensy? Audiobook files can easily span 45 minutes ("cassette length"), 60+MB at stereo medium quality, though lower bit rate mono might be adequate for this task. Does the audio + MP3 library approach require reading a file from SD card and decoding it before playing (presumably lengthy, and memory-hogging), or can that be done piecemeal while playing?

2) Seek functions: Looking at the library headers, I see various Play related functions (and readable position), but I don't see functions that would allow seeking forward or back by say 1 minute or 10 minutes (or a seek-to-time function with which to implement jump forward/back). Have I missed something in this area? Is there a tractable approach to that, or would that get deeply involved?

Thanks. Graham
 
Seeking isn't really supported. Some people have hacked it into the raw player. 45 minutes as raw (uncompressed) mono would be about 227 megabytes, which fits easily on any modern SD card.
 
Seeking isn't really supported. Some people have hacked it into the raw player. 45 minutes as raw (uncompressed) mono would be about 227 megabytes, which fits easily on any modern SD card.

Thanks for the reply.

If some people have implemented seek in the raw player, I'd be interested in seeing that, if someone could point me to it.

Yes, one "tape side" readily fits on an SD card, however an example book I'm targeting has 50 such sides -- so using raw mono that's 12GB or so. Except that it would be nice for the SD card to contain numerous such books, and to provision them over the net (not direct to Teensy though). Hence the interest in MP3s rather than raw.

Regardless, raw is an option, and it sounds like seek is more plausible with the raw player than MP3. I assume because for MP3 you have to do something more clever to interpret the compressed MP3 stream starting at an arbitrary byte location in the file.
 
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