mad-dev April 2002

mad-dev@lists.mars.org

20 participants
13 discussions

api
by Henning, Brian 16 Apr '02

16 Apr '02

Hello- I have compiled the mad library on my windows 2000 machine using mingw. I have the libraries and headers now. Can someone guide me to some documentation for the mad api? Is it online? I didn't find it on the website but, maybe I just missed it. I would like to write a simple program that reads in mp3 frames and prints to the screen some info in the headers. Is there any example programs in the documentation? I would like to see a simple example of some code to read a frame/header and print it to the screen. thanks for any help!!! brian

2 1

frame decoding question
by Haig C Didizian 11 Apr '02

11 Apr '02

Hello - I hope this question doesn't fall outside this list's domain, but I figure there's probably a ton of mp3 know-how in this group... :) Anyway, I was looking at the mp3 headers from a file, and my calculation of the frame length appears to be wrong, but I can't figure out why. The first frame of the file looks like this: ff f3 68 64 which tells me that this is a 48kbps MPEG2 Layer-3 file at 16000Hz in joint-stereo, which is true based on what madplay says. I'd like to calculate the frame size based on this info, and using this equation for Layer-III files from http://www.dv.co.yu/mpgscript/mpeghdr.htm - FrameLengthInBytes = 144 * BitRate / SampleRate + Padding I calculate that the frame size is 432 bytes. When I scan through the file given this information, I find a total of 1924 frames. When madplay scans through the file, though, it finds twice as many, 3848 frames. So it seems that my frame length is 2x too big. Why does this equation hold for my 128kbps version of the same file, but not for this version (or am I missing something obvious)? On that note, does anyone have any suggestions for an mp3 frame-related resource? The one I mentioned above seems decent, but if there are any better ones, I'd love to know... Thanks for any help, Haig

3 4

Static and dynamic linking
by Gareth 11 Apr '02

11 Apr '02

Hi, Once I had compiled minimad for ARM using the Lart cross compiler I used the 'file' command to see some stats on the resulting executable. It tells me that the file is an ELF arm executable, dynamicly linked (uses shared libraries) and a few other things. Now shared libraried are linked at runtime, right? So when I take the minimad executable and dowload it onto the arm evaluator board the shared libraries will be left behind and it will not work. Is this reasoning correct or am i missing something? If I am correct how do I go about telling the compiler to do static linking? Thanks Gareth

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mad-dev April 2002