#133: ALSA's SND_PCM_FORMAT_U16_BE (and LE) not supported, Allegro fails to
initialize sound
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Reporter: izm | Owner: lennart
Type: defect | Status: assigned
Priority: normal | Milestone:
Component: module-alsa-* | Severity: normal
Resolution: | Keywords: allegro alsa format snd_pcm_format
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Comment (by elias):
Well, the format is specified to be unsigned, and data are user
accessible. And it's like that since almost 10 years, so there's no way we
can change it now - whatever the reasons were back then to choose
unsigned. (Likely, soundblaster 1.0 or whatever was current then used
8-bit unsigned, then when 16-bit support was first added, it was kept
unsigned.)
Now, the above change does an XOR with 0x8000 on each 16-bit sample right
before providing data to Alsa. So if that indeed is such a waste of
resources (myself I'd hope you can hardly notice any performance penalty)
- then I'll have a hard time arguing for applying the above change, as
Alsa itself certainly can do a much better job converting the format.
What really is needed is a simple way when initializing Alsa to query if
it can support unsigned 16-bit (it which case Allegro will keep providing
that) or not (in which case we can convert ourselves).. but I wasn't able
to learn from the Alsa docs how to do that, after a quick glance.
--
Ticket URL: <http://www.pulseaudio.org/ticket/133#comment:7>
PulseAudio <http://pulseaudio.org/>
The PulseAudio Sound Server
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