From mboxrd@z Thu Jan 1 00:00:00 1970 From: Clemens Ladisch Subject: Re: [RFC][PATCH 00/15 v4] OXFW driver, a succesor to firewire-speakers Date: Wed, 13 Aug 2014 09:06:06 +0200 Message-ID: <53EB0E5E.40004@ladisch.de> References: <1399991272-5807-1-git-send-email-o-takashi@sakamocchi.jp> <53E795BD.1070100@ladisch.de> <53E957EA.3030601@sakamocchi.jp> <53E9BDC2.3000801@ladisch.de> <53EA9901.40306@sakamocchi.jp> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from dehamd003.servertools24.de (dehamd003.servertools24.de [31.47.254.18]) by alsa0.perex.cz (Postfix) with ESMTP id 3E25D2654E9 for ; Wed, 13 Aug 2014 09:06:07 +0200 (CEST) In-Reply-To: <53EA9901.40306@sakamocchi.jp> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: Takashi Sakamoto Cc: alsa-devel@alsa-project.org, stefanr@s5r6.in-berlin.de, fenlason@redhat.com List-Id: alsa-devel@alsa-project.org Takashi Sakamoto wrote: > On Aug 12 2014 16:09, Clemens Ladisch wrote: >> Takashi Sakamoto wrote: >>> On Aug 11 2014 00:54, Clemens Ladisch wrote: >>>> The old driver configured nothing but the rate. Is there any mechanism >>>> to set the stream format? >>> >>> Yes. It's AV/C stream format information command. >>> [...] >>> But in this series of patches, I don't use this command. I expected the >>> models to change stream format according to parameters in AMDTP packets >>> such like the value of dbs field. >> >> Apparently, the firmware doesn't support automatic format detection >> completely, and requires this command for the 2ch 32/44.1 kHz modes. > > Apparently and completely, why? Please tell show reasons to judge about > a lack of automatic format detection. When you developed and committed > firewire-speakers driver, you confirmed all of combination for PCM > rate/channels, didn't you? When I wrote the driver, Jay tested which combinations did actually work (without any stream format information command; I don't have the spec), so that's what the driver ended up supporting: - 6ch at 32/44.1/48/96 kHz - 2ch at 48/96 kHz If snd-oxfw also does not send the stream format information command, then I guess that 2ch at 32/44.1 kHz will not work either. > [...] > Instead, we should consider the 2ch modes. This mode seems to be used > for Dolby Pro Logic II and Dolby Digital but I don't know about the > specification of Dolby something. If we drop these modes, the work to > develop OXFW driver becomes simpler. The driver does not need care about the format itself; the data is just sent as 16-bit words that pretend to be samples. All the driver has to do is to handle the "non-audio" bit in the "IEC958 Playback Default" or "IEC958 Playback PCM Stream" mixer controls; this can be added later. Regards, Clemens