[MPlayer-users] Re: audio filters drain the cpu

[Fredrik Eriksson]

Fabio Papa wrote:

> Fredrik Eriksson wrote:
>
>> Tobias Diedrich wrote:
>>
>>> Fredrik Eriksson wrote:
>>>  
>>>
>>>> playing a audiofile like
>>>>
>>>> mplayer music.mp3
>>>>
>>>> works just fine, without any notable cpu usage. However, trying to 
>>>> use a audiofilter, like
>>>>
>>>> mplayer -af sub music.mp3
>>>>
>>>> or
>>>>
>>>> mplayer -af surround music.mp3
>>>>   
>>>
>>>
>>>
>>> I can reproduce that on my SB Live.
>>> Can you try the attached patch and see if it makes the problem go 
>>> away for you?
>>>
>>> It seems like snd_pcm_status_get_avail returns something not a
>>> multiple of chunk_size, but snd_pcm_writei only writes multiples of
>>> chunk_size.  The while-loop in ao_alsa then retries with the remainder
>>> and the next call to snd_pcm_writei is busy-waiting.
>>>  
>>>
>> That patch worked somewhat, now most of the time the cpu usage is 
>> down to a more reasonable level (about 1-2%), but at times it still 
>> goes up to 99-100% for no apparent reason, and then goes down again.
>>
> Just for the sake of discussion, have you determined wheter you're using
> OSS or ALSA as output device? I've seen the exact same behaviour as you
> two, but the problem went completely away using ALSA instead of OSS...
>
> Fabio.

Building audio filter chain for 44100Hz/2ch/s16le -> 0Hz/0ch/??...
alsa-init: 1 soundcard found, using: surround51
alsa: 44100 Hz/6 channels/12 bpf/196608 bytes buffer/Signed 16 bit 
Little Endian
AO: [alsa] 44100Hz 6ch s16le (2 bytes per sample)
Building audio filter chain for 44100Hz/2ch/s16le -> 44100Hz/6ch/s16le...
Video: no video
Starting playback...

quite certain I'm using alsa...