From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Hofman Subject: Re: Via VT82xx VT1708 ICE1724HT and higher sample rate/bit depth files through SPDIF Date: Tue, 26 Feb 2008 15:36:20 +0100 Message-ID: <47C423E4.4060900@insite.cz> References: <068801c8783e$f5456390$d450a8c0@PDSMain2> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable Return-path: Received: from prague.insite.cz (r3g29.net.upc.cz [213.220.198.29]) by alsa0.perex.cz (Postfix) with ESMTP id 8312724340 for ; Tue, 26 Feb 2008 15:36:29 +0100 (CET) In-Reply-To: <068801c8783e$f5456390$d450a8c0@PDSMain2> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: Demian Martin Cc: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org Hi Martin, > = > First- sample rate > = > Even though the documents claim that it will play at 176.4 KHz and 192KHz > whenever I play a file at these rates it down converts to =BD the rate (8= 8200 > and 96000). I tested this with the ICE1724HT (Juli@) which has almost the > same core, I never could get 176.4KHz at the SPDIF output. I confirmed th= at > the ICE1724 will play the file at 176.4KHz in Windows so its not a hardwa= re > limitation. I tried to do the same with the VT1708 (on a Via CX700 chips= et) > and the Windows driver wouldn=92t let me at anything other than 48000. = I spent a few days on this issue and confirm that ICE1724HT cannot output 176.4kHz from its internal SPDIF transmitter, WHEN clocked by its internal clock circuits. A scope hooked to corresponding pins/outputs revealed the following: All I2S lines output correct 176.4kHz signal, i.e. D/A codecs receive proper signal. However, I did not find a way to force ICE1724 to output 176.4kHz, it always drops to 88.2kHz, no matter what MT01/MT02 combination is. The = same happens with windows drivers of my Prodigy 192. The sequence is: = 44.1, 48, 88.2, 96, 88.2, 192 I have not seen any manufacturer of Envy-based cards revealing this deficiency. The "preliminary" datasheet we all use mentions only that the chip forces the 128x mode when switched to 176.4kHz. I believe the = output of 88.2kHz is an undocumented feature or perhaps even a bug of = the chip. Juli is a card whose manufacturer may be aware of the problem. It is not clocked by ICE1724 internal clocks fed by the two crystals. Instead, the = crystals also provide signal to external circuits generating clock signals of required frequency, feeding the chip in slave mode. The = circuitry is controlled by ice1724 GPIOs. This way the ICE1724 is not aware of its clocking frequency and cannot = thus mis-configure its SPDIF transmitter. The windows driver does output proper 176.4kHz. I am working on Juli driver and have been analyzing this beast for a few nights. The special clocking is already working at home :) > Second, the only way I can get the 24 bit files out in a form that the ca= rd > can play is to pass them through dmix. But I need to reconfigure dmix for > each sample rate. And I=92m not convinced that it isn=92t resampling twic= e, both > at the input and the output. Or how to configure the buffers etc. to prev= ent > underruns even when the only conversion is to pass a 24 bit file to the > card. ICE cards use 32bits format. Try aplay -v -D plughw:0 24bit.wav and you will see the conversion to 32 bits done by the plug plugin, no dmix involved. > = > I=92m trying to build a high quality music server that will pass the file= s to > either the internal or an external DAC at the bit depth and sample rate t= hey > were recorded at. I have tried to understand the various plugs and settin= gs > but it seems they are all focused on mixing various streams. I want to se= nd > the files unmixed to the output. I can=92t figure out what set of plugs a= nd > settings in asound.conf would enable this. Check the plug plugin. Regards, Pavel Hofman. ----------------- inSITE, s.r.o. Kafkova 16, 160 00 Praha 6 Rubesova 29, 326 00 Plzen Tel., fax: +420 - 37 - 74 493 58 GSM: +420 - 603 - 163 973 Email: pavel.hofman@insite.cz www.educity.cz, www.insite.cz www.meetings.cz, www.hrzive.cz www.comben.cz, www.hr-online.cz