Echo canceller/suppressor produces tick noises.

[nanang]

Currently there are two known noise sources in echo_common.c:

• Before the latency buffer ready, pjmedia_echo_playback() doesn't modify the input frame. However, once latency buffer is ready, input frame is modified/replaced by internal pjmedia_delay_buf_put(). This transition causes zero-samples gap somewhere in the early stage of playback.
• Inappropriate usage of delaybuf in echo_common.c may produce periodic noises when there is sound device clock drift, i.e: capturer works faster than player.

[nanang]

Test application to reproduce the tick noises.

[nanang]

In r2757:

• Fixed noise from EC by keeping the playing frames unmodified pjmedia_delay_buf_put() may modify the input frames and there is a case that the modified frames are not aligned anymore).