davidm

Just in case anyone does want to know about deriving wordclock / digital audio sync from timecode..... Historically, this goes back to the introduction of computer based editing systems having to accurately follow timecode either from an analogue tape recorder or a VCR. The solution was to gearbox the editing systems speed (wordclock) from the timebase of the incoming LTC. A good example of that technology in production today is the Nunedo / Colin Broad Electronics Syncstation. http://www.steinberg...n_details0.html As Philip Perkins noted, Mark of the Unicorn have included timecode to wordclock software with their audio interfaces - MOTU SMPTE Console. My first Metacorder setup in 2005 used a MOTU Traveller and the software looked as though it had been around since OS9 days. At the time I used a Lockit with wordclock and didn't spend much time with the SMPTE Console. Stephen Buckland, General Manager at Sound Techniques here in Auckland has kindly lent me a MOTU UltraLite MK III for the weekend so that I could verify that the software worked. Unlike the Traveller, the UltraLite doesn't have a wordclock input so the SMPTE Console software would be useful if anyone wanted to run Metacorder or BoomRecorder with this interface. Another scenario would be running any MOTU interface with a high quality TC only source. The test: I sent TC from a Lockit into the UltraLite CH1 audio input and ran AES3 Black Audio from the Lockit into CH1 of a dual trace Oscilloscope. I then connected the UltraLite SPDIF output to CH2 of the Oscilloscope. The Oscilloscope showed SPDIF had no sync relationship with the Lockit timecode / wordclock. I then selected SMPTE as the clock source in the SMPTE Console. Within 10" the SPDIF signal could be clearly seen slewing around the AES3 Black Audio signal. It took about 1.5 minutes to stabilise. At sample level the UltraLite continued to hunt up and down 1.25 samples every 15 seconds or so. Comparing the TC output from the Lockit (one of the new ACL204 Lockits with dual TC outputs) and the SPDIF signal on the oscilloscope showed the same minor hunting up and down. Practically, the UltraLite has held sample stable sync from a timecode source for past 6 hours of measurement.

I'm a proponent of auto syncing and (as near possible) perfect TC matches between camera and sound. Auto syncing with the appropriately specified cameras, audio recorders and timecode / sync generators provides for synch accuracy to a 1/10th of a frame or better and assuming all the vision from any number of cameras and sound is in a non linear format and loaded into Avid or FCP bins, syncing of a days rushes can take 10" or so. On the basis of sync accuracy and efficiency the process is the "state of the art" and has been in use since the mid 1990's The principle is that the alignment of camera frame starts and the TC stamp in the audio can be created accurately in the original field recordings and that when imported into a frame based editing system, that accuracy is maintained until someone in the post chain moves it around or as been noted earlier in this thread, you just happen to be sitting near the back of a cinema and sound is delayed a frame or two due to the laws of physics. By comparison, syncing using traditional slates or timecode slates on frame based editing systems where there is no alignment of camera frame starts and the TC stamp in the audio results in sync variations of between 0.00 and 0.99 fames. No one knows within the duration of the vision frame exactly when the slate occurred. It can be argued that sync accuracy of between 0 and 1 frame is just fine and decades of productions have successfully been made with this level of resolution. In reality, if a production is using Lockit's on the cameras, chances are they are auto syncing in an Avid. There's an expectation of near as perfect sync between camera and sound and this is achieved everyday worldwide. When the wheels fall off the bus, as Hopkin and others have discovered, it's a problem figuring out what's going wrong and the sound mixer always gets the blame. With offset bugs and frame based syncing the simple solution might be bumping a frame here or there without any analysis of cause of the problem. With buggy auto syncing, there's just a lot work fixing sync and quite possibly, a disgruntled production and post team and still no methodical analysis of the problem. My first ever Lockit shoot was in 1995. My new StellaDat and couple of Sony Digital Betacams. For the first 2 or 3 weeks there were numerous random frame errors. Much angst and memos flying all over the place inferring the Lockits weren't working Suddenly everything went quiet. It transpired that post had a basic Digidesign interface which wasn't frame accurate. They then acquired a Digidesign Slave Driver and the frame error evaporated. To this day that post faciltity specialises in auto syncing rushes. Getting back to the essence of the thread, here's some comments on Alexa's. As Simon Bishop and others have noted, it's said that the Alexa won't hold a new Tune value when fully powered down and defaults back to the factory reference. I only ever seem to do short term shoots with Alexa's and haven't had the opportunity to verify this but it does present a dilemma for accurate sync. On the other hand, every Alexa I have checked with an ACC501 hasn't been far off Ambients GPS reference standard. Sebastian Fell at Ambient commented in an email last year about a variation of the Ambient technology that Arri had implemented some time ago in the SR3 timecode system and more recently in the Alexa that provides for accurate sync with an external Lockit. "It can also (which is the mod of the Clockit) auto-tune to an incoming time code, which it does when it is in EXT. TC / REGEN mode. It then generates TC, but follows the incoming code closely, a kind of "sync & lock", as we called in in the old days in the recording studio... As the whole camera is clocked from the tunable crystal, this means that the camera is then indeed synced to the external TC, meaning that the picture sensor will not drift against the TC" So if anyone is feeding a tuned Lockit into an Alexa in EXT TC / REGEN Mode, it would seem that's as good as it gets. It's tweaking the Alexa's master sync generator so don't feed just any old flavour of timecode or Mark Wielage might justifiably have heart palpation's.

Hi Simon, I read your post just before Friday wrap and as I was heading out for for a couple of glasses of wine, I naturally didn't give it much consideration until today. Hopkin used a 60ms delay or about 1.4 frames and you are correct that the delay that I observed is about 15ms. Some of that 15ms delay will be A/D conversion of the timecode going into the audio input. I have followed this thread since the outset and it's been difficult to add anything to the discussion that would help resolve Hopkins problems. Some interesting theories though.

Hi Hopkin, Here's how to test if your recorder has random offsets in the BWF timecode stamp. Setup the recorder for internal timecode use. Take the timecode generator output and feed it into audio channel 1 with the TC at about -10dB. Make a series of recordings of at least 1 minute in length. 20 takes would be a good number. You could just feed timecode onto a spare track of your production recordings on a typical work day. Next, you need two items, the Ambient ACC501 Controller which you have and 2nd, a friendly audio post facility as you will need a Pro Tools HD system or equivalent that can output 23.976 timecode and is locked to stable sync Import the audio files into Pro Tools and snap them to thier timecode locations on the timeline. You'll need cables from the Pro Tools timecode output to the ACC501 input and from the Pro Tools audio channel output to the ACC501 input. You may need to adjust the audio level output so that it's a level acceptable to the ACC501. Each files will be played one at a time. The process is to play the file and jam the ACC 501 from the timecode output. Then switch the cables to the timecode on the audio track. As you are in LTC mode, the ACC501 Controller will display any difference between the recorders timecode output (TC on the audio track) and the timecode on the BWF metadata( from the Pro Tools TC output)) down to about 0.01 of a frame. I ran some tests over the past week with files from a colleagues Fusion (V7.55) and my 788T (V2.19) at 25fps. The 17 Fusion takes had a relatively constant offset between the TC on the audio track and the TC from the timeline of 0.35 or 0.36 frames. The 20 788T takes had a relatively constant offset between the TC on the audio track and the TC from the timeline of 0.05 or 0.06 frames. I'd guess some of the offset is due to AD conversion on the audio input. So while my tests indicated the Fusion may have a more significant (but sub frame) offset compared to the 788T, there was no random offset in the current software. A note on my Pro Tools setup. I use a Pro Tools 10 Native system using wordclock from a Lockit and for timecode, one of the few MIDI-SMPTE interfaces that can handle 23.976, an Ambient ALL 601.

I have been looking for any interesting new products released over the last few days at IBC in Amstedam. Has anyone found anything apart from the following. Audio Wireless Ltd have a Timecode Link which can be switched to receiver transmit modes. It's in the same enclosure as their radio mic transmitters and is programmable across a 500MHz range of 430 - 930MHZ. http://www.audiowire...link-at-ibc2012 Sennheiser have a new digital wireless system for theatre and broadcast applications. They claim to have spent over 12m euro (USD 15.3m plus) on their new 9000 system. No word on transmission method or how many channels can work together in a block. http://en-de.sennhei...com/9000-series Sennheiser have also added the 8090 wide cardioid to their MKH 8000 series. http://en-de.sennhei...rom-sennheiser-

As I read the HD-P2 manual, in the "Clock Source" menu, the user selects the source of clock which includes the "timecode" option. This would imply that a signal such as WC going into the BNC would not be used. The external clock capability of the HD-P2 would appear to be the amongst the most flexible available. As with the Fostex PD606 and SD 788T it takes composite and Tri-Level sync in addition to word clock. Regardless - best engineering practice for use of external timecode with cameras or audio recorders is to use common sourced word clock or genlock. Timecode only is 2nd best.

There's some interesting theories in this discussion. "thesoundguy" is maintaing that you can't get wordclock from timecode. Phil Perkins takes the view that professional recorders can use external imecode as a sync source for their word clocks. Timecode was fundamentally developed in the late 1960's and early1970's as both a time address and sync source. Although it's only a slow rate of 2400 baud, there is a sync start to a frame in that stream of 1's and 0's. Assuming the timecode source is accurate and stable, it's possible to compare the timebase of an external timecode against a recorders internal timecode timebase and use the difference to slew the recorders wordclock so that it's effectively the same speed as the incoming timecode. An example of this was the now obsolete Rosendhal Wif / Nuendo TimeLock Pro. The internal wordclock generator is resolved to incoming LTC or VITC. I'm not aware of any Sound Devices recorder that can sync it's wordclock to incoming timecode. I re-read my 788T & 744T manuals and there's no reference to this feature anywhere. Just in case it's an undocumented feature, I reference tuned my 788T and a Lockit with a Master Controller and hooked up the wordclock outputs to a dual trace oscilloscope. Both wordclock signals were stable against each other. I then detuned the Lockit by 4ppm. The 788T was set to external timecode from the Lockit and I left them to run for 2 hours. The wordclock signals never stabilised into sync, which IMHO, disproves Phil Perkins comments regarding the SD recorders ability to "automatically" sync wordclock to incoming timecode. However, the Tascam HD-P2 can sync it's wordclock to the incoming timecode (owners manual P21). Does anyone know of any other recorders that can sync their internal wordclock to external timecode? David M

My Venue has a very low level whine when its connected to my Sonosax ST8D and is powered from a comon DC source. The whine is related to the LCD screen on the Venue as it will change in pitch when I switch screens. My Venue output level is +08. I found 2 solutions. The 1st was to lift the earth at one end of the audio cables connecting the Venue to the Sonosax. This solved the whine from the Venue but resulted in more noise on those Sonosax channels when I power up my Mac Mini. The 2nd solution was to power the Venue from a fully isolated DC-DC converter and thats my current arrangement.

The significant change you made was " ...have set my lockit box to send me bi-level sync into my big Ben". The Lockit is now the sync master for your system by supplying low drift genlock signal.

...and daisy chain the Fireface 400 WC input off the DM1000 WC out.

I agree with thesounguy's explanation of timecode and sync. However, I suspect your problem is the Big Ben. It's a music grade clock, just like your FireFace and DM1000. By music grade I mean while it no doubt produces low jitter and perfectly formed clock signals, the oscillator was never designed to broadcast video specs of 1ppm or better drift. It could be anything from 10ppm to 1000ppm which means it might be fine for 10 or perhaps 20 minute takes and even then it might be a frame or more out of sync. Apogee don't publish a ppm spec for the Big Ben but as an example of a music grade clock, Yamaha spec the DM1000 at 1000ppm. Not good. Use the wordclock out of your Lockit to feed the wordclock input of the Big Ben. It's a 1ppm or better grade clock and can be tuned to 0.2ppm. The clock source on the Big Ben should be set to WC. Feed the TC to Metacorder. On the stage, if you can get your video people to send you composite video from their sync pulse generator, you can use that as an external clock source for the BIg Ben. The Big Ben can't handle try-level sync. I also wouldn't trust the cameras to be in sync over long periods despite what editorial tells you unless they have Lockits or Denecke Sync Boxes on them and are using both TC and Video Sync. There's nothing like an old school clap stick at beginning and end of a long take to see who's in sync and who isn't. David M (Metacorder with a Metric Halo2882 interface. WC & TC from an Ambient reference tuned 744T = less than 0.04 frames drift in 10 hours against the best video sync available).

There are two parts to this process. 1) Decode the LTC on the vision A1 or A2 tracks into timecode metadata. This is done using the "Read Audio Timecode" function in the Avid "Special" menu. With this function, the Avid samples the audio track from beginning to end and works out the start TC. 2) Copying the timecode stamps in the audio BWAV files from the Avid TC column into the Aux TC column. The concept here is that the AVID can only autosync identical fields of a bin. Method: Import camera video with TC recorded on A1 or A2 & the BWAV files from the audio recorder (788T) into the Avid. Audio: Duplicate the "SndTC" column into the "AuxTC" column of the audio bin. Use the "Apple•D" shortcut & Avid will ask you which column to copy into. Select "AuxTC". Video: Use the "Read Audio Timecode"; function in the Avid "Special" menu. Select the vision audio track that has the timecode (A1 or A2). The destination track should be the default "Auxiliary TC1". Click "OK" and the LTC is decoded. This can be done as a batch for multiple camera files but may take some time depending on the total duration of the vision. Perform an Auto Sync using the Aux TC fields of the audio and vision files. Select "Auxiliary TC1" as the sync source in the "Auto Sync" menu.

For a DIY approach, I'd suggest a DC:DC converter such as a Traco TEL 2-1210 instead of a regulator. While I haven't used these for low current, low voltage applications such as powering radio mic transmitters, I do have three Traco's on my cart providing various stable voltages with a high level of input to output isolation. As the outputs float relative to the input, there's a good chance that any ground related noise issues can be resolved.

IMHO, the Rycote Baby Ball Gag has so much plastic in it's construction that the sound is dulled and and with the Rycote Fluffy the sound is muddy. If you need a hard wearing product the Rycote is probably the toughest. My Rycote Baby Ball Gag sits unloved in a cupboard. The Schoeps B 20 S is a lightweight ball basket with inside and outside layers of fabric over the plastic frame. Sound is transparent compared to the Rycote and provides for excellent air movement protection with rapid boom moves. The Schoeps web site lists a single fabric layer W 20 variant and I believe the "Fuzzy Basket" is the W 20 R, a single layer fabric basket and a slip-on "fluffy. I obtained a Cinela Leo for an MKH50 last March. It's one fabric layer over a minimal lightweight plastic frame. There's a fluffy for it is well but we haven't used that yet. The Leo is a significant wind performance and sound quality advance over the Rycote Baby Ball Gag. Check with Cinela first for use on a CCM as their web site notes the Leo-20 is for use with a CMC. The yoke of the Leo ball that fits over the mic body is quite long compared to the Schoeps and Rycote Balls and may cover the mic capsule slots when pushed up against the suspension supporting the CCM.

Nosferatu is correct. To sync the camera use the "Video" settings for Rotary Switch 2, not the "Word Clock / Audio" settings. Rotary 1: Pos 3 (1080P) Rotary 2: Pos 3 (29.97) Rotary 3: Pos 5 (29.97 drop) The word clock only comes into play if you are driving your audio recorder with wordclock & TC from the Lockit: Rotary 1: Pos 5 (Word Clock) Rotary 2: Pos 3 (48KHz) Rotary 3: Pos 5 (29.97 drop)

A double flash on a Lockit is the low battery voltage indicator.

I use a relatively flexible RG58 with the longest lengths being 50'. I have an antenna bar with Lectro shark fins on a stand which can go up to just under 15'. I also have a small antenna bar with a pair of dipoles that mounts on my cart mast when I don't need the big rig. I usually have plenty of lighting and grip equipment between my cart and the sets and I find height overcomes all reception issues and cable loss relative to antennas mounted on my cart. My crew would riot if I turned up with heavy, non flexible antenna cable. However, I've been considering a pair of powered antennas and after reading a post from Larry Fisher in September last year, I intend to power them direct from my Venue and let the dipoles trip the polyfuse whenever they are used.

Cinela can supply an alternative XLR mount / swivel component which has a wider spacing from the boom that will allow for a Lectrosonics HM or similar plug-on transmitter. Part number is SW-LB.

Thanks Marc. I suspected a poorly written manual. It's a mute Epic / 5D shoot. The editor asked for a timecode slate on any 5D vision filmed at the same time as Epic.

I was asked to setup an Epic to jam sync to external timecode from a slate today. The timecode source menu was switched to external and the incoming timecode was verified by a green highlighted "TC" element in the main display. The timecode appeared to auto jam correctly as the Epic timecode numbers continued to count correctly after the external timecode was disconnected. What seems odd is that the manual says the camera can be placed in "Jam Sync mode" and there is a "SYNC" (Jam Sync) element on the main display but there is no description of how this actually works or under what conditions the "SYNC" element would be highlighted. Firmware 2.0.5 (current version) Can any Epic experts out there shed share some knowledge on this?

Greg, I don't think you'll get any significant noise improvement by using the Neve preamp over the 788T. Preamp noise performance is traditionally measured as "equivalent input noise" referenced to a 150 or 200 ohm resistor. The thermal noise of a 150 ohm resistor is -130.9 dBu and a 200 ohm resistor is -129.6 dBu. Sound Devices don't do us any favors here by stating their "EIN" for the 788T but have a look at some specs of other products: SD 302: -126dBu (? ohm) SD 744T: -128dBu (150 ohm) Sonosax SX-ST: -128dBu (150ohm) Neve 5015: better than -128dBu (150 ohm) The Neve can't deliver more than a 2.9dB noise improvement over a 744T because of the -130.9 dBu limit and in the big scheme of things, there's not much in it. The 788T noise performance expressed as EIN is likely to be around -128dBu. I agree with Tom Visser in that you won't find a quieter mic than a MKH60 going by it's noise spec. The Sennhesier MKH series have always had an edge on other capacitor mic's. But again, in the big scheme of things, they don't necessarily deliver a significant practical noise performance advantage over say a Schoeps mic. Microphone preamp noise and the microphones inherent internal noise are always evident when undertaking quiet ambience and subtle sound effect recordings. Of course some might prefer the thermal noise "color" of one particualr microphone or preamplifier.....

Never mind the data, what about the bandwidth? This project requires antenna arrays from VHF up to microwave. It also requires clear spectrum and that's why relatively unpopulated parts of Western Australia would be a great place to host this project. While the glossy pictures have microwave dishes pointing to the sky, there is little indication if the VHF and UHF arrays will or will not also be sited in eastern Australia and New Zealand. One of the two New Zealand sites (Ardmore) is 25km from the centre of our largest city, Auckland. I picked up the following from some South African background papers. The VHF & UHF spectrum will require an extraordinary low level of RF background noise by todays standards. If the 606 - 614 MHz radio astronomy band is used, 8MHz either side would be needed as guard bands. A 10 watt transmission at 300km distance would be a problem. So there goes another 20 to 24 MHz of TV / radio mic bandwidth. I just wonder if the radio astronomy project people have talked to the radio spectrum managment people.

The ebay website says their Lexar readers are limited to 2GB CF cards. Any luck with higher capacity cards?

I had the same fault last Saturday. I'm running V2.16. It seemed to me that it couldn't find the either the CF or hard drive media. I had been recording on both. I tried selecting hard drive only as the record media but the 788T seemed intent on only looking for both media. After powering down and up again the 788T went into a mode which said something like "installing USB and Firewire drivers". After that was finished it still wouldn't go into record. After connecting to my laptop to remove the audio, I removed the Sandisk CF card and the 788T returned to functioning as normal. CF card was pre formatted. I have since reformatted all my CF cards using "Erase" in the 788T.

Those Yagi's antennas are made by Lintec in the UK. http://www.lintec-antennas.co.uk/pages/catalogue/cat_yagis.html Here's a better picture of the Yagi range on the Canford web site. You can order through Canford or purchase direct from Lintec. http://www.canford.co.uk/Products/28-801_LINTEC-LBY-RADIOMIC-ANTENNA-specify-frequency You can specify the frequency, bandwidth and number of elements and they'll make them up. David M Auckland, NZ.