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Topic: sound/video on embedded linux (Read 3794 times)
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jku
Zebranky food
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Posts: 14
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I now have uqm running acceptably on the maemo platform / Nokia 770 *, and I'm currently looking into what kind of settings I should change to make it more enjoyable.
I've already halved the "Low quality" SDL audio frequency and channels (into 11025 and 1) in audiodrv_sdl.c. This lowers the amount of buffer underruns to almost zero. If someone has a hunch about the lower limits of "acceptable quality" regarding those numbers, I'd love to hear it.
Is there something else (sound/video quality-wise) I should take a look at?
There is a dependency for vorbis libs, but my content pack (uqm-0.5.0-content.uqm) doesn't seem to contain any: Are oggs used only in the larger content packs? Can the dependency be easily dropped, or am I missing something?
Also, any general performance hints are greatly appreciated. Thanks, -jussi
*) Nokia 770 Technical info: processor: TI OMAP 1710, 220 MHz ARM fpu: none memory: 64MB RAM + 128 MB Flash (+rs-mmc) screen: 800*480*16 TFT
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Novus
Enlightened
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Fot or not?
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Vorbis support is not used for the standard content package. You should be able to remove Vorbis support by editing the files in src/sc2code/libs/sound/decoders; removing oggaud.* and removing the references to Ogg Vorbis in decoder.c ought to do the trick (I'm surprised there isn't a build configuration option for this). You may also want to remove .DUK video and audio support while you're at it.
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jku
Zebranky food
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Posts: 14
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Thanks fellas, that'll get me going...
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jku
Zebranky food
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Yeah, Tremor is what I currently have -- but I don't think I'll be keeping it: I believe the only way to use the larger content packages would be to use the external rs-mmc disk for storing it (even that would usable only for a small amount of people as Nokia ships only a pitiful 64MB rs-mmc with the device), because of limited internal memory.
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fossil
Core Team
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To answer your sound question, the original sound effects and MOD music files are mostly sampled at 8363 Hz (a couple are even sampled at 4181 and 2090 Hz, believe it or not). If this Nokia device can do playback at this frequency natively, you can save a lot of CPU time by not having to resample the audio. The current mixer resampling implementation is a floating-point one, and Nokia 770 does not have an FPU (if I am reading the specs right). We are planing to refactor the mixer code some time in the future, and one of the goals is to get rid of floats in mixer resampling code.
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jku
Zebranky food
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Posts: 14
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Thanks, fossil.
Your spec-reading skills are fine, and I believe your suggestion is good -- although I cannot test that in the near future: I had to send my device to Nokia maintenance because of faulty wlan chip. The scratchbox dev. environment is pretty neat, but sound is obviously something that cannot be tested on it...
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