> how can I read the mp3 data outputted by lame frame by frame? I noticed
> in common.c that all the bits are stuffed into a bit stream and then
> shoved down the pipe, I couldnt figure out though, before that point, when
> each frame was formed? My point in doing so: I want to serve the
> microsoft media client. they require that the frames are all of uniform
> size and that there is some funky header preceding each mp3 frame. that is
> why I need the individual frames. and also, where can I find out the
> individual frame sizes in bytes? I emailed mark taylor already regarding
> individual frame size uniformity, and he told me that I just need to set
> the padding bit to 0 in order to have uniform frames, will this cause
> problems of any sort? thanks a bunch yall.
> -kali
>
You will probably have to be more specific. An MP3 frame looks like:
header
side info
data
The size of the frame varies by at most one byte (at 44.1khz). AT
48khz, all frames will be the same length.
However, the actual encoded coefficients for a given frame will
usually be spread over two frames. For example, 20% of it might be in the
data block of the previous frame, and 80% is stored in the data
block of the current frame.
This size of the encoded coefficients is variable, it can range
from 0 to 6000 bits more or less, and it is impossible to make
every frame use exactly the same amount of data.
Because of this, a frame is not a selfcontained unit. You
usually need at least two frames before you can decode one frame worth
of data.
Some decoders work by creating new "meta frames" which contain
the header, side info and all data associated for that frame.
If MS wants this kind of information, you are going to have to
really muck around with the bitstream. The mp3asm code does some
of this.
Mark
--
MP3 ENCODER mailing list ( http://geek.rcc.se/mp3encoder/ )
