At Tue, 20 May 2014 17:20:44 +0800, Kailang wrote:
At Tue, 20 May 2014 16:52:43 +0800, Kailang wrote:
At Tue, 20 May 2014 15:15:49 +0800, Kailang wrote:
Hi Takashi,
HP machine had pop noise via speaker. If EAPD on or off, speaker will have pop noise. So, they want to set eapd to follow with stream on or off.
I can apply this as is, but still I wonder whether this results in other problems. Doing EAPD on/off there means that it happens far more often. For example, what happens if you do like below?
while true; do echo -n > /dev/snd/pcmC0D0p doneAnd, what if the device is resumed from power-saving by an audio playback? Immediately after the power up, it'll start the streaming, so it'll turn on EAPD.
That said, isn't it just a need for some delay before EAPD on/off?
No, eapd on or off will cause pop noise.
Does it do always?
No, pop noise just one pop sound. It can not remove by software. But this machine need to do this always.
So, doing EAPD on/off often is rather worse. It's what your patch does.
Once again: did you try the script above? If the pop noise always happens, the operation like above is the worst scenario.
Then, let's think again how to *reduce* it. We need one EAPD on at least after each power up. But it's needed only when you actually plays a stream. That is, we need only enable EAPD at playback stream open, but leave EAPD as is at close.
Takashi
Our customer just want to do eapd on when stream is open. The pop noise will not clear. Because music gain was biger than pop noise.
Opening a stream doesn't mean that it follows the loud sound immediately. The script above wouldn't produce any sound but just does open/close the stream. Did you try that?
Takashi
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