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Author Topic: Blu Ray into HDMI Phil Ranucci Expert Film Handler Posts: 236 From: Carpinteria,CA, United States Registered: May 2006 posted 02-07-2015 12:23 PM                     We've been trying to run a BluRay into the HDMI input on a GDC media block. Picture is fine, but the audio is only L/R, not 5.1. Audio routing on the server seems correct. According to GDC, the media block just passes thru the audio. Anybody have an idea? the players are set to output PCM, is this correct? Thanks!  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 02-07-2015 12:54 PM                        What's the sound on the BD, and what sort of audio processor are you using? At one of our theaters, I have a BD player going into a cat745 thru HDMI, and the audio from the 745 to a CP650. If the disc has Dolby 5.1 or 7.1 on it and the player is set to use that, it plays OK. But if the disc only has DTS multi-channel sound, I can only get L/R stereo. To get the Dolby 5.1 or 7.1, I have to select bitstream audio out on the player, but if the disc is DTS only I have to configure the player to mix it down to 2.0 L/R, or else there is no sound at all (because the CP650 can't decode DTS). At the other theater, we have two DVD/BD players (one for region A, the other for region B) going into an Intelix scaler, with the output from that going thru HDMI into an AP20. The AP20 can decode Dolby and DTS and automatically recognizes each one. But again, you have to select bitstream (in effect, audio data pass-through) on the players, or else again, you get L/R only. For some reason, most consumer DVD/BD players seem to mix down the HDMI audio output to 2.0 L/R as a factory default setting, I'm guessing to minimize the number of "low information consumers" who would fail to get any sound when connecting them to a cheap TV that doesn't have Dolby and/or DTS decoding, and then return them to the store if the default was bitstream/pass-through and let the device on the other end decode the proprietary system compressed audio.  |  IP: Logged Stephan Shelley Jedi Master Film Handler Posts: 854 From: castro valley, CA, usa Registered: Nov 2014 posted 02-07-2015 01:55 PM                     I know others have said no elsewhere but I have tried it and the Dolby Cat 745 does decode the Blu-Ray AC3 5.1. via hdmi and the configuration script on 4.8.x asks if your sound processor can do advanced sound like 96khz sample rate. I suspect that that is Dolby supporting there own AC3 format. I know it does not work on pre-Dolby Doremi IMBs. Software may fix that in the future.  |  IP: Logged Harold Hallikainen Jedi Master Film Handler Posts: 906 From: Denver, CO, USA Registered: Aug 2009 posted 02-07-2015 02:17 PM                        Is that true? I was not aware of any IMB that decodes encoded audio since they were designed to play DCPs, which are PCM. I do think that IMBs may pass encoded streams from HDMI to AES/EBU for decoding in the sound processor. To me, it would be so much simpler if the BLU ray player would do the decoding and just put PCM on the HDMI. It's much less expensive decoding in the BLU ray player since they are made in much higher volume than cinema equipment. Harold  |  IP: Logged Stephan Shelley Jedi Master Film Handler Posts: 854 From: castro valley, CA, usa Registered: Nov 2014 posted 02-07-2015 02:38 PM                     I have tried it at two different locations with Dolby Cat 745 with CP650s. It does work. 650 was set to 6 channel pcm. Playing a Blu-Ray into the HDMI on the Cat 745, Blu-Ray set to Dolby 5.1 there was sound coming out of all the channels like it should. Like I said I think it is Dolby supporting their own. One of the locations was with the original USL made Cat 745.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 02-07-2015 03:08 PM                     Could be a setting in the ADMIN/GDC panel to adjust audio from HDMI, but this area is password protected. Call up GDC Support on this question. good luck-Monte  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 02-07-2015 03:37 PM                     quote: Phil Ranucci the players are set to output PCM, is this correct? Nope, set the bluray player's output to "bitstream". Also if the player has a setting for secondary audio, set it to off so it doesn't compress the HD original mixes.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 02-07-2015 04:19 PM                     I believe the AC3 thing is allowing it to passthrough and having the EDID table list that audio as an option...not that the decoding is done in the IMB. So when you configure your DSS server, you are really also setting the EDID table. But in general, what you hear from an HDMI feed is what was coming off the player/source. If you use "Bitstream" then you are allowing encoded data (Dolby OR DTS) to be on the HDMI line...you better make sure you have a suitable decoder downstream that can handle it. As others have noted, Dolby only decodes Dolby brand audio streams (the CP750 only does AC3, at that) (and LPCM). Datasat decodes High and Low bandwidth DTS and low-bandwidth Dolby (e.g AC3 but NOT True HD). If all you have is a BluRay player as a source, I agree with Harold on this one, let the player decode whatever audio is on the disc to the maximum capability of your sound system (5.1 or 7.1) and let it come to the sound processor (via the IMB, in this case) already decoded. It is the safest bet that everything will work and at the highest quality.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 02-07-2015 05:52 PM                     Stephan, How does the 745 identify the source on the screen?  |  IP: Logged Stephan Shelley Jedi Master Film Handler Posts: 854 From: castro valley, CA, usa Registered: Nov 2014 posted 02-07-2015 07:04 PM                     The audio source? I think it would do like the DMA 8+ does on the s/pdif and toslink inputs, if it detects an AC3 bitstream it decodes it otherwise it expects PCM. DMA 8+ can also do Dolby E which it also auto detects.  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 02-07-2015 07:58 PM                        quote: Marco Giustini How does the 745 identify the source on the screen? In the control tab of Show Manager, there's a pull down menu toward the bottom left, from which you select server (i.e. DCP data coming in thru cat6), HDMI1 or HDMI2.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 02-08-2015 04:32 AM                     Sorry guys, I was not clear! What I meant was: what does the ShowManager say about the source being fed to the 745 on the screen? I can't remember on top of my head if it displays the audio or just the picture properties. If the 650 is set to 6ch input, then the 650 is not decoding anything. What I am trying to find out is whether the BD player is actually sending AC3 or 5.1 LPCM - the latter being officially supported by the 745. Sometimes it's hard to find out what a BD player is actually outputting.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 02-08-2015 11:43 AM                     Above the time line on the control screen, it will indicate the format (picture and sound). I know that the CAT745 handles AC3 in some form (and I think it is from an EDID point of view so the processor downstream can decode it). I say that because AC3 was addressed in on of the release notes of the Dolby software. I have personally never sent AC3 down the HDMI pipe to the CAT745. Here is an image from the 4.7.0 release notes. I ovaled the area where it will tell you the formats involved.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 02-08-2015 01:58 PM                     Ok, so what happens when AC3 is sent to the 745 and the sound processor is not capable of AC3 decoding?  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 02-08-2015 05:26 PM                     As the Dolby slogan used to be..."Silence." But that is what EDID is supposed to prevent. If nothing says it can handle AC3 (or whatever format) then the source shouldn't put it on the line. Next time I get a chance (and I think I will pretty soon), I'll give it a try though.  |  IP: Logged

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