writing .wav file to sd card??

I want to store a wave file to a sd card, and which library should i use, i need to record from input A0 ad store it to memory card. i am able to save it as text, but ofcourse there is format for wav file, but not able to do it Plz help me out. Have to do it urgently :(

I don't think you can do this. This is because writing to an SD card can not be done at a steady regular rate so the sound file needs to be buffered. There is not enough memory on an arduino to do this. You might get more luck using a Mega with an external memory shield.

let say, i have record speech signal upto 5kHz only, then i think it should be possible, i just want to write a wav file to sd, it may get be slow. i just want to know. how to write a wave file to sd card??

I wrote a library to record speech quality audio using the Arduino internal ADC http://code.google.com/p/waverp/.

WaveRP is an Arduino library for recording and playing Wave files with the Adafruit Wave Shield. It records 8-bit mono files at 4,000 to 44,100 samples per second.

Use of the Wave record/play library, WaveRP, requires the following:

Arduino with a 5 volt 328 processor.

Low noise power source such as a nine volt DC adapter or battery.

Adafruit Wave Shield (version 1.1 is best but 1.0 works)

Microphone preamp. A circuit for a simple preamp is included in the documentation.

Microphone, PC type with 3.5 mm plug. See the documentation for details.

SD/SDHC formatted with 32KB allocation units.

You don't need the Wave Shield if you only want to record. The Wave Shield has a DAC and amplifier for playing Wave files in addition to an SD interface.