From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre-Louis Bossart Subject: Re: Direct Stream Digital (DSD/DST, One Bit Audio) HDMI pass-trough Date: Mon, 13 Oct 2014 17:56:44 -0500 Message-ID: <543C58AC.9000701@linux.intel.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by alsa0.perex.cz (Postfix) with ESMTP id 773EA2604DA for ; Tue, 14 Oct 2014 00:56:56 +0200 (CEST) In-Reply-To: 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: Andrej Falout , alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org On 10/11/14, 1:33 AM, Andrej Falout wrote: > Hello, > > I am collecting requirements for implementation a DSD HDMI pass-trough, > according to HDMI specs version 1.2 and 1.3a > > I am wondering if anyone previously worked on this, or has any interest in > this functionality. > > Any advice or pointers are gratefully received. Here is my list of the core > facts so far: > > > 1. hda_eld.c in current kernel git ignores raw DSD (One Bit Audio) > labelled AUDIO_CODING_TYPE_SACD ("SACD" because originally DSD formats > where only used commercially in SACDs) and compressed DSD (DST) is labelled > AUDIO_CODING_TYPE_DST (1) > 2. It is my understanding that apart from "special handling" denoted in > "Table 47 CEA Short Audio Descriptor for Audio Format Codes 9 to 13", (eg > setting the format code, etc) this should be a reasonably straightforward > stream pass-trough (2) > 3. Typical use scenario for DSD over HDMI: an DVD/BluRay player that > supports SACD (Super Audio CD) outputs a DSD stream over HDMI to a DSD > capable receiver. For instance, my Oppo and Sony BluRay players both do > that, and all my receivers (Onkyo, Pioneer, Marantz, Yamaha, NAD) have DSD > DACs and I can play both stereo and surround music this way, without > converting DSD to PCM. There is currently about 30 million DSD capable > receivers on the planet, conservatively speaking (Just Onkyo makes 1 > million a year, and makes DSD capable ones since 2003) > 4. Wanted scenario: play DSD files using DSD enabled players (Linux: > MPD, mplayer, VLC, Squeezeboxserver, etc / Windows: FooBar, JRiver, etc) to > an HDMI audio card/device on a PC motherboard or add-on video card with > HDMI, connected via HDMI cable to a DSD enabled receiver/DAC > 5. Note that as far as I know, no proprietary drivers on Windows > (ATI/AMD, Nvidia, Intel) support this; It will be the first time a device > that is not a SACD player outputs DSD over HDMI, on any OS. I am assuming > that this has nothing to do with hardware limitations of the HDMI chips > used for video outputs (I could not find any reference for such assumption > in any HDMI chips I examined specs for). Therefore, I assume that > implementing this has no hardware prerequisites. HDMI controllers typically don't support DSD in the PC space. It'd be easier to convert to high-res PCM (HBR). > 6. DSD format general info: > http://en.wikipedia.org/wiki/Direct_Stream_Digital http://dsd-guide.com/ > http://dsd-guide.com/what-dsd-audio-simple-explanation > > > > Thanks, > Andrej Falout > > References: > (1) > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/sound/pci/hda/hda_eld.c?id=refs/tags/v3.17 > - Same source file in Alsa GIT tree: > > http://git.alsa-project.org/?p=alsa-kernel.git;a=blob;f=sound/pci/hda/hda_eld.c > > (2) CEA Standard PDF, page 66, table 47. HDMI specs version 1.3a, pages > 72-73 for DSD(One Bit Audio) and DST audio packet header and body formats > > > <%2B385%2891%291520436> > _______________________________________________ > Alsa-devel mailing list > Alsa-devel@alsa-project.org > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel >