Date: Mon, 08 Feb 1999 19:12:56 +0100 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Archie Cobbs <archie@whistle.com> Cc: hm@hcs.de, freebsd-isdn@FreeBSD.ORG Subject: Re: audio bitorder (was: Re: Problem with ELSA Quickstep 3000) Message-ID: <4907.918497576@critter.freebsd.dk> In-Reply-To: Your message of "Mon, 08 Feb 1999 09:40:52 PST." <199902081740.JAA26903@bubba.whistle.com>
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Thanks for the explanation. I'm still leaning against a "let us try all the ports in ports/audio and do whatever the majority does" approach... In message <199902081740.JAA26903@bubba.whistle.com>, Archie Cobbs writes: >Hellmuth Michaelis writes: >> > And while we're on this issue, did we change the bitorder of the >> > A-law to be compatible with programs like sox etc ? >> >> I've talked to Stefan Bethke about this, and i'm still not convinced which >> bitorder is the "right" one: > >The "right" bitorder for A-law/U-law data as it travels over an >ISDN line is most-significant-bit first. This is so your D/A >converter can start converting the sample upon receiving the first >bit. > >Also, traditionally bytes are transmitted over HDLC serial connections >with the low-order bit first (for example, Ethernet -- that's why >the low-order bit of the first address byte determines unicast vs. >multi- or broad-cast). > >So the HSCX is being consistent here in treating an 8-bit A-law/U-law >quantity as having the most significant bit in bit position zero. > >However, this "seems" backwards and that is probably why /dev/audio >does it the other way around. > >-Archie > >___________________________________________________________________________ >Archie Cobbs * Whistle Communications, Inc. * http://www.whistle.com > -- Poul-Henning Kamp FreeBSD coreteam member phk@FreeBSD.ORG "Real hackers run -current on their laptop." FreeBSD -- It will take a long time before progress goes too far! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isdn" in the body of the message
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