playing wave using CAPI

[k***@gmail.com]

Hi everyone,
I know this is a very old topic, but I am having a bit problem with it
so I have to raise it again here.
I have already written the CAPI program to play the wave file (a-law, 8
bit 8kHz mono). I can hear it from the phone on the receiver end. The
problem is that even though I can recognize the voice from the wave
file, it is full of background noise.
So, I don't know what has gone wrong. Please help. Please note that:
- The same wave file played via media player is clear
- My CAPI program read the wave file and start reading from the sample
data behind "data" trunk.
- Bit - reversing has been done
- I have tried xOR with 0x55, but still have many background noise.
- I am using a buffer of 2048 to send data through CAPI. Buffer of size
512 byte does not make much difference.
- I am using an analog Eicon card.

What else can I try ? Thanks.
Kelvin

[k***@gmail.com]

Hi everyone,

I found the reason. One of the bit was reversed wrongly. After that was
corrected, the sound is very clear.

Post by k***@gmail.com
Hi everyone,
I know this is a very old topic, but I am having a bit problem with it
so I have to raise it again here.
I have already written the CAPI program to play the wave file (a-law, 8
bit 8kHz mono). I can hear it from the phone on the receiver end. The
problem is that even though I can recognize the voice from the wave
file, it is full of background noise.
- The same wave file played via media player is clear
- My CAPI program read the wave file and start reading from the sample
data behind "data" trunk.
- Bit - reversing has been done
- I have tried xOR with 0x55, but still have many background noise.
- I am using a buffer of 2048 to send data through CAPI. Buffer of size
512 byte does not make much difference.
- I am using an analog Eicon card.
What else can I try ? Thanks.
Kelvin