[olofsonprojects] Re: kobodeluxe in OpenEmbedded
- From: Robert Schuster <theBohemian@xxxxxxx>
- To: olofsonprojects@xxxxxxxxxxxxx
- Date: Sun, 10 Feb 2008 18:01:08 +0100
Hi David.
David Olofson schrieb:
> Unless the rotation is implemented in hardware, I'd think it's SDL that
> does the rotation. If so, that would mean SDL uses an internal shadow
> surface, and that may well mean that you get a different pixel format or
> something.
It is done in HW I think. They support this through xrandr.
> Or perhaps there is something wrong with alpha blending in that SDL
> version...? (That would likely be disabled when a shadow surface is
> used, as many APIs only accelerate blits to the screen.)
Looks like it. By using "noalpha" text display worked nicely on the
Nokia as well as the Neo1973. However it is much slower now.
> Does it attempt to use hardware acceleration for the blits?
How can I find this out?
Now that I changed it to "noalpha" one time, I wanted to make a log with
alpha and therefore switched back. Interestingly it now paints
characters. At least somewhat:
http://scap.linuxtogo.org/files/25385fcb760b269ce797d5e43b67b6c1.png
Strange.
> [...]
>> interferes) but otherwise it is ok.
>
> Ok. Might have to up the buffering/latency a bit then... Or maybe lower
> the mixing quality, if the CPU load is the problem.
>
> What's the output sample rate? (If it's significantly lower than 44.1
> kHz, it might cause the adaptive oversampling to kick in and increase
> CPU load, as many of the sounds are rendered at 16 kHz or higher.)
I set it to 8k. With that it works quite good.
> BTW, would you know if the audio driver supports memory mapped I/O, ie
> shared DMA buffer? (That would allow substantial buffering for solid
> playback, alongside with "asynchronous" mixing for near zero latency.
> Stock SDL doesn't support that, but most backends already use memory
> mapped I/O, so it shouldn't be too hard to get at those buffers if desired.)
On the Neo this may be possible since they have a proper ALSA driver for
their Wolfson chip. However on the Nokia all sound output is done
through gstreamer. They patched sdl to do this, too. Their reason is
that as a gstreamer plugin (which is LGPLed) they could keep the codec
proprietary ... :(
Regards
Robert
Other related posts:
