Date: Mon, 25 Aug 1997 19:20:31 +0200 (MET DST) From: Luigi Rizzo <luigi@labinfo.iet.unipi.it> To: multimedia@freebsd.org, optimedia@opti.com Cc: luigi@labinfo.iet.unipi.it (Luigi Rizzo) Subject: OPTI931 information Message-ID: <199708251720.TAA20043@labinfo.iet.unipi.it>
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NOTICE: This message is sent to optimedia@opti.com and the mailing list multimedia@freebsd.org since people on the list can be interested in the subject. --- I have a problem with the OPTI931 chip (both silicon rev.0.1 and rev.1.0) used in MB mode. The chip is mounted on a couple of audio cards marked "ExpertColor MED3931" which I have. The driver for FreeBSD I have developed, whose sources are available at http://www.iet.unipi.it/~luigi/FreeBSD.html is able to control the card in full duplex and all formats, _except_ capture ULAW data. When I request capture of ULAW data (either stereo or mono, it seems to make no difference) I get instead signed-16bit samples, probably stereo (I cannot tell if they are stereo or just come at twice the desired sample rate). ULAW playback works fine. The driver works fine with other formats, and with other MSS clones such as the CS4236. I have read very carefully the data sheets of both the OPTI931 and of the CS4236, and cannot find any reason for this behaviour. Besides, the fact that all formats except ULAW capture work (using the exactly the same code, the only change is the value written in the I28 register which controls capture format) makes me think of a bug in the chip. For sure it can be masked in software by the device driver, but I would like to know first if this is really a bug, or what am I supposed to do to make ULAW capture work. I would be very grateful if tech support people at OPTI, or other people who have had experience programming this chip, can shed some light on this behaviour. Thanks Luigi -----------------------------+-------------------------------------- Luigi Rizzo | Dip. di Ingegneria dell'Informazione email: luigi@iet.unipi.it | Universita' di Pisa tel: +39-50-568533 | via Diotisalvi 2, 56126 PISA (Italy) fax: +39-50-568522 | http://www.iet.unipi.it/~luigi/ _____________________________|______________________________________
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