Harman Kalra wrote:

Can you please explain difference between signed and unsigned PCM

formats,

Signed PCM formats have a sign, unsigned don't. S16 allows values in the range -32768..32767, U16, 0..65535.

in what cases does unsigned is used,

In practice, never. It was historically used by some 8-bit cards.

which is more efficient (memory and sound clarity)

I refer the honourable gentleman to the reply I gave in the last mail.

...

If you tried to set MPEG format, ALSA would inform you that the device does not support this.

    But when I queried the hardware regarding the supported audio

formats using the api " snd_pcm_format_name", it responded with a list of formats, including , A-law, u-law-, IMA_ADPCM, MPEG, GSM, so what does it mean.

It means that the sample format identified by the constant SND_PCM_FORMAT_MPEG is indeed named "MPEG". This has nothing to do with what formats some particular hardware supports.

  What would be audio sample file size in case of A-law, will it be

same as U8.

I refer the honourable gentleman to the reply I gave in the last mail.

Regards, Clemens