Subject: Re: [linux-audio-dev] MP3 Decoder wishlist
From: Andy Lo-A-Foe (andy_AT_alsaplayer.org)
Date: Tue Feb 26 2002 - 20:35:01 EET
On Tue, Feb 26, 2002 at 06:44:32PM +0100, Guenther Sohler wrote:
> * puts pcm data into an array piecewice(eg convert 1000 samples at a time)
MAD decodes to pcm samples, it's up to you to 'take' the nr of samples
you need each time.
> * somehow gets the mp3 stream
You can give the decoder a mmap()'d area with encoded bytes, so
basically an array with your mp3 data.
> * need to seek to any position in time (in mp3 file)
There are various methods of doing this, if you need absolute sample
accurate seek the most reliable method is to first determine the mpeg
frame positions (i.e. parse the whole mp3 file beforehand).
> * simple c code example
I wouldn't call the alsaplayer mad plugin simple but it does everything
you want. The mad_play_frame() call will return a fixed amount of pcm
samples per call. the seek function is also pretty much sample
accurate() (since reverse play works flawlessly).
> I looked into MAD, but id drove me MAD because there is no sample code for
> low-level application
Yes there is, just not in the MAD distribution :)
Good luck,
Andy
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