[mythtv-users] Alsa Prealloc Query

Zooka mythtv at fitzy.org
Thu Dec 16 01:38:36 UTC 2010


On 16/12/10 11:27, Jean-Yves Avenard wrote:
> On 16 December 2010 07:55, Zooka<mythtv at fitzy.org>  wrote:
>>> What kind of content were you trying to play? (sampling rate, sample
>>> format (16, 24, 32 bits) and how many channels?
>>
>> This is the ffmpeg -i output.  Is this sufficient?
>>
>> Stream #0.1[0x433](eng): Audio: ac3, 48000 Hz, stereo, s16, 384 kb/s
>>
>>
>>> If you could reproduce the original condition and run mythfrontend -v
>>> audio and upload the log in pastebin.ca
>>
>> http://pastebin.ca/2020698
>>
>
> Interesting...
>
> We asked for a 200ms length buffer, yet ALSA gives us 110ms.
>
> To get 200ms of audio, we need:
> 48000 * 2 (channels) * 2 (bytes per channel) * .2 = 38400 bytes = 37kB.
>
> So a 64kB buffer should be plenty.
>
> I had made some assumptions on how ALSA worked, seems it's not the
> case for everyone.. bugger..
>
> JY

No prob, I should note that it is not causing any difficulty, I just 
thought it a little strange.


More information about the mythtv-users mailing list