[SDL] Re: dspaudio & FreeBSD - huge delay [testcase]

Mattias Engdegård f91-men at nada.kth.se
Sun Apr 2 09:06:51 PDT 2000


> In fact there is two buffers in the driver - one
>frontend, which behaves accordingly to theh OSS specs, and one (usually
>large) backend, which is used to actually transfer data into card. And what
>makes this situation even worse, is that all ioctl's expected to return
>current state of audio buffers in fact returns only state of the front
>buffer, which in the most cases is empty, as the driver tend to transfer data
>into its back end buffer ASAP.

If there is no way to resize or get status information of the backend buffer,
then you are stuck. You can use it for playing music, but nothing latency-
critical. It sounds brain dead to me.

>I've notified FreeBSD developers about my findings and will try to persuage
>them to fix audio driver for better conformance with OSS specs.

Is OSS the native audio API of FreeBSD, or is it just a compatibility layer?
If so, there could be a way to handle it. Do the BSD developers have the
ambition to use other APIs in the future (ALSA, OpenAL)? The OSS/SunOS
concept where an app talks directly to a device isn't a very flexible design.






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