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Author Topic: DCP Digital Sound Formats Question Mitchell Dvoskin Phenomenal Film Handler Posts: 1869 From: West Milford, NJ, USA Registered: Jan 2001 posted 06-17-2012 07:39 PM                     Pardon what may seem like a stupid question from one who has not yet directly dealt with digital cinema. What digital format is the sound? Does the server output a bit stream comparable to a 35mm reader that can be fed into an existing Dolby Digital and/or DTS processor, or is it a new digital format, or does the server output the discreet channels directly in analog, or none of above?  |  IP: Logged Claude S. Ayakawa Film God Posts: 2738 From: Waipahu, Hawaii, USA Registered: Aug 2002 posted 06-17-2012 07:51 PM                        As a patron of the cinema and not a projectionist, I always wanted to know the same thing you had asked, Mitchell -Claude  |  IP: Logged Terrence Meiczinger Film Handler Posts: 45 From: Orono, Me, USA Registered: Dec 2008 posted 06-17-2012 08:04 PM                        A DCP contains an MXF audio file. The MXF file holds discrete audio channels in uncompressed WAV PCM format. So, 7.1 audio is literally 8 channels, no encoding or compression.  |  IP: Logged Jock Blakley Expert Film Handler Posts: 218 From: Melbourne, Victoria, Australia Registered: Oct 2011 posted 06-17-2012 08:36 PM                     The discrete WAV files are then fed out of the server as a digital bitstream. Newer processors like the Dolby CP750 can accept this directly, but older processors can't so a DAC is used to convert the AES/EBU stream to an analogue signal that uses the same connection standard as DTS and so is accepted by the External 6-Track input on your processor of choice. Since we use both DTS and D-Cinema (albeit DTS very rarely) we have a switcher that allows us to change between DCI and DTS from the front of the rack rather than continually switching the DB25 plugs at the back of the CP500.  |  IP: Logged Claude S. Ayakawa Film God Posts: 2738 From: Waipahu, Hawaii, USA Registered: Aug 2002 posted 06-17-2012 08:39 PM                        So a MXF audio file is a totally new digital sound format making Dolby, DTS and SDDS sound processors obsolete with digital cinema. Am I correct to assume this? -Claude  |  IP: Logged Jock Blakley Expert Film Handler Posts: 218 From: Melbourne, Victoria, Australia Registered: Oct 2011 posted 06-18-2012 11:17 AM                     MXF stands for Material Exchange Format and isn't specifically a type of audio file - instead it's simply a container for other files. Think of it as a box that is made to precise standards and can be opened by anybody who knows how. A DCP contains two MXF files - one for audio and one for picture. The audio MXF contains anywhere between 1 and 16 audio tracks, with one discrete track for each channel (in the same way that 70mm had discrete tracks rather than a matrix like optical Dolby Stereo). Each of these tracks is in the Broadcast Wave format (BWFF) with linear pulse-code modulation (LPCM). This is far from a totally new format - BWFF was first defined by the European Broadcasting Union in 1997 and is derived from the Waveform Audio File Format (WAV) that we all know and love and thank Microsoft and IBM for all the way back in 1991, and the PCM encoding dates to 1972. The picture MXF file contains every frame of the film* stored each as an individual JPEG2000 file. ( * = or every frame of that particular "reel", but that's an unnecessary complication right now) As to obsolescence though - yes, your DTS-6D will be obsolete on the same day your Cinemeccanica or Century or Simplex or Christie or Philips or Kinoton becomes obsolete. I can't speak for SDDS because I have zero experience with the system and zero knowledge of the capabilities of its processors. Basically though any film-only sound decoder or processor or playback system will be irrelevant in a digital-only cinema for very obvious and unsurprising reasons. Dolby's later processors will remain relevant even if you completely ignore the film options because, as I mentioned before, the D-Cinema server's AES/EBU sound output is directly accepted by the CP750 and can be very easily adapted for the External 6-Track (Format 11) input on the CP500 and CP650, as well as certain earlier models. Doremi supply their AUD-D2A unit expressly for this purpose and I imagine other vendors have such a unit too. If SDDS processors ever had six-track-in for DTS than the same point stands for them.  |  IP: Logged Mitchell Dvoskin Phenomenal Film Handler Posts: 1869 From: West Milford, NJ, USA Registered: Jan 2001 posted 06-18-2012 07:52 PM                     Thank You.  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 06-18-2012 09:55 PM                     quote: the D-Cinema server's AES/EBU sound output is directly accepted by the CP750 and can be very easily adapted for the External 6-Track (Format 11) input on the CP500 and CP650, You do NOT need to use an outboard adapter for the CP650, you just need the CAT 790 Card. It will then accept the AES/EBU bitstreams directly. That leaves your external 6-channel input available for other uses. The only known drawback to the CAT 790 approach is that evidently some CP650/CAT790 combos can get a fit of "Robo-sound" on occasion. So far I haven't encountered it although others here have. EDIT: See THIS THREAD  |  IP: Logged Jock Blakley Expert Film Handler Posts: 218 From: Melbourne, Victoria, Australia Registered: Oct 2011 posted 06-18-2012 11:25 PM                     Ah, very true Tony, I mentally changed "can cause robosound" to "not possible" without realising.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 06-18-2012 11:59 PM                     Other processors can use the USL eci60 interface unit to convert the digital stream into 6 channel analog to work with their aux 6 channel input setups. CP500's will then use "Format 11" - the same format that DTS used.  |  IP: Logged John Wilson Film God Posts: 5438 From: Sydney, Australia. Registered: Dec 1999 posted 06-19-2012 12:34 AM                     A weekly re-boot of the 650 seems to keep ROBOSOUND at bay.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 06-19-2012 02:25 AM                     Nope, not so John. I tried everything possible to prevent the ROBO SOUND on a 650. I have tried: Never turning the 650 off Powering the 650 off overnight Power cycling the 650 off for 5 minutes at the end of each show The more power cycles it was given, the more frequent ROBO SOUND attacked me. Screw it...Format 11 to the rescue!  |  IP: Logged Jock Blakley Expert Film Handler Posts: 218 From: Melbourne, Victoria, Australia Registered: Oct 2011 posted 06-19-2012 04:27 AM                     quote: Format 11 to the rescue! Too true - although in our case it's more because it'd be a tad painful to replace our CP500-70 for the same amount of convenience and rack-space.  |  IP: Logged Scott Jentsch Phenomenal Film Handler Posts: 1061 From: New Berlin, WI, USA Registered: Apr 2003 posted 06-25-2012 09:47 AM                        I knew that the audio was PCM, but I'm surprised that it is not losslessly compressed in any way. Maybe they feel that there's more hard drive space right now than there are CPU cycles to decode a compressed stream, but I see this as something that will most likely change in the foreseeable future.  |  IP: Logged Jock Blakley Expert Film Handler Posts: 218 From: Melbourne, Victoria, Australia Registered: Oct 2011 posted 06-25-2012 07:04 PM                     Why would that be, Scott? Already the soundtrack represents only a fraction of the storage and processor-time requirement relative to the picture, and that gap is only going to increase as resolution and frame-rates climb.  |  IP: Logged

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