Peter Gray - Director of Photography

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Single-System & Double-System Sound Recording Techniques with the Sony 24p HDW-F900 CineAlta, and the Panasonic Varicam AJ-HDC27V/V-M1/F Camcorders

An outline of the various methods for recording separate audio with the Sony 24p High Definition camcorder. The HDCAM's popular frame rate of 23.976fps and its related timecode, presents us with brand new production issues to take into account. The techniques presented here describe various ways of mixing dissimilar timecode bases, namely 23.976 and 29.97, to facilitate production and post production procedures.

The order of presentation is from the simplest most basic options, going towards the more complex, yet more versatile systems.

(1). Single-system sound only

Simply use the CineAlta camcorder as the master audio recorder. The audio mixer, or microphone/s are hard wired, or radio linked, directly to the audio section of the Panasonic Varicam or Sony CineAlta camcorders. Record simple in-camera timecode in the normal way using either continuous-running (time-of-day) or REC-RUN timecode.

Advantages: Simple and elegant. There are no sync or other timecode issues to worry about, or get wrong. Slating is optional, as it is only needed for identification purposes only. Or the slate can be simply "bumped" for a few seconds prior to rolling, to record the slate information. No syncing or other manipulation of the audio is required for post. If the audio is RF (radio linked) to the camcorder, then the system is extremely compact and flexible. Ideal for "run-and-gun", or hand-held documentary-style shooting (which will be one of the main reason to using this method). Also good for very basic, no-frills, low-budget shooting.

Disadvantages: No DAT back up of the audio, so the production is completely dependent on the integrity of the original audio on the HDCAM tape. Doesn't work with multi-camera set ups if the additional camcorders are recording when the "A" camera is not running (seeing "A" is the master audio recorder).

*******All of the following options are for a double-system audio setups*******

(2). Non-timecode DAT Backup for Low-Budget Production

This is the most basic double-system of all - very simple and cheap. It is basically the same as the Single System set up above, but with an independent DAT audio recorder added to the system. The idea is to simultaneously record backup audio to a DAT machine, which is intended for emergency use only. A non-timecode capable DAT can be used, meaning cheaper consumer DAT recorders are suitable for this purpose. Slating at the head of each shot is necessary.

If all goes well, the backup audio may never be needed during the post. It would only be needed in the (hopefully) unlikely event that you need to substitute original audio with backup audio, because of problems with the master sound on the HDCAM tape itself. So if it turns out the backup audio is needed for whatever reason, then it will require manual lip-syncing in the Avid ( or similar non-linear editing system). The sync relationship between the audio and the image can be established using the slate reference (i.e. clap).

Advantages: Simple and cheap. No timecode to worry about, so no special equipment needed, like timecode locking or conversion boxes. No wires connecting the camera and DAT apart from the audio feeds and return, that can be radio linked if required. Almost as simple and streamlined as single-system sound, but adds simple audio backup for added confidence, and emergency use if needed.

Disadvantages: Slating is necessary. Although a viable backup of the audio is provided for emergencies, it requires manual syncing up in the post without the aid of timecode.

(3). Simple Double-system with Timecode DAT Backup

The next level of sophistication, so to speak. The audio mixer, or microphone/s are hard wired, or radio linked, directly to the audio section of the Panasonic Varicam or Sony CineAlta camcorders, making it the master audio recorder. Record with 23.976 timecode in the camcorder in the normal way.

Simultaneously record the audio to a DAT running 29.97 timecode (Non Drop Frame preferred). Slating is necessary at the beginning of every shot. Use either REC RUN or continuous-running (time-of-day) F RUN timecode with a 10 second pre-roll on all camera/audio start ups. (Note: The 10 second pre-roll is required by ONLINE assembly systems used in post.)

Advantages: No wires connecting the camera and DAT apart from the audio feeds and return that can be radio linked if required. No special equipment needed, like timecode locking or conversion boxes. Can use either REC-RUN or continuous-running timecode.

Disadvantages: Slating is necessary, although a simple non-timecode slate can be used. If using a timecode slate, periodic jamming is necessary (see method #4 below). Need a 10 second pre-roll on all camera/audio start ups if using continuous-running timecode. Syncing of the audio is done manually in post by lining up the corresponding clapper board reference (clap) on both the picture and the sound elements. The timecode between image and audio bears no special relationship to each other.

(4). Simple Double-system with Timecode DAT Backup, employing a Smart Slate

Similar to method #3 above with the refinement of adding a linked timecode slate. The master audio recorder is the 24p Camcorder running normal 23.976 timecode. The DAT is used as an audio backup recorder running at 29.97 (Non Drop Frame preferred). The DAT sends its 29.97 timecode to a timecode slate or smart slate. The slate can either be radio linked or hard-wired to the 29.97 timecode source. The smart slate must be shown to camera at the beginning of each shot, and/or clapped in the traditional way. Either continuous running (like time-of-day) or REC-RUN timecode can be used, as the relationship between picture and audio is established by the slate only, either from the "clap" and/or the visual timecode reference.

Advantages: Periodic jamming of the Slate is not necessary. No special timecode translator boxes required. No cable connection or jamming required between camcorder and DAT.

Disadvantages: In the case where you need to use the backup audio, the editor needs to sync everything manually in the non-linear editing system, using the references provided by the clapper board (timecode reference or clap). The visual timecode reference on the ‘Smart Slate' relates back to the audio timecode only.

(5). Simple Double-system with Timecode DAT Backup for Multi-camera Configurations

This description assumes a two-camera set up, but the same principle applies for more than two camcorders. The audio mixer, or microphone/s are hard wired, or radio linked, directly to the audio section of one, or both, the HD camcorders. One, or both, camcorders are considered to be the master audio recorder. Record with 23.976 timecode in both camcorders in the normal way. Simultaneously record the audio to a DAT running 29.97 timecode (Non Drop Frame preferred).

Without specialized equipment like Ambient ‘Lock-it' boxes, it is not normally possible to cross jam a system using different timecode like this. However, it is possible to jam the two camcorders using a cable connection from the timecode-out BNC on Camera ‘A', connected to the timecode-in BNC on Camera ‘B'. After the timecode numbers lock, this cable can be disconnected. The DAT will have its own independent 29.97 timecode. Syncing points must be established by the use of a slate in the traditional way.

Using a Smart Slate to Cross Jam:

But please note, no currently available DAT recorder can cross jam directly to an external 23.976 timecode source. However, there is a way to do this using a timecode slate as an intermediate step to facilitate the cross jamming process. You can cross jam 23.976 timecode coming from one of the HD camcorders to 29.97 timecode using a suitable timecode slate. For example, the Ambient Master Slate, or a later version of the Denecke slate that is capable of doing this. You need to cross jam the Timecode Slate to the designated master Camcorder ‘A', and next jam the DAT from the Timecode Slate. To complete the jamming of timecode across this system, you would connect a cable between the timecode-out BNC on camcorder ‘A', to the timecode-input BNC on camcorder ‘B' (as described above). After the timecode numbers get in step with each other (or lock together), this cable can be disconnected during shooting. This system would need to be re-jammed every few hours, depending on how quickly the various timecode generators drift from each other. Some timecode generators will probably be more stable than others, so it is a question determining the weakest link and to periodically re-jam accordingly.

The timecode numbers will now (more or less) match between the two camcorders and the audio. In the case of the two camcorders, they can be up to a single frame out of step with each other (see comment below). As for the DAT recorder, its numbers will only match on the first frame of every second. In other words, timecode numbers with corresponding hours, minutes, seconds, and "00" frame numbers will match. But the timecode numbers will not match exactly until the next "00" frame numbers come around once again, one second later.

NOTE: In this type of set up, it is possible that the two cameras might be out of sync with each other, by up to one frame. This is because this method is a simple timecode jamming process, and is therefore independent of the camcorder's internal sync. The moment of jamming can occur at slightly different times within the camcorder's recording cycle for each frame, thus creating a possible offset of up to a single-frame discrepancy between two or more camcorders in a multi-camera set up. This problem can be overcome by feeding all camcorders identical timecode that is referenced to an external sync generator. See method #13 below using the ‘Clock-it'/‘Lock-it' system, or similar.

Slating is necessary at the beginning of every shot when making use of a simple mechanical slate. Both camcorders must be recording, and both must see the slate at the moment of clapping. Or alternatively, the DAT can jam 29.97 timecode to a timecode slate or ‘Smart Slate' (or this can even be radio linked or hard-wired to the 29.97 timecode source). The smart slate must be shown to both cameras at the beginning of each shot, and/or clapped in the traditional way for added safety.

You must use continuous timecode, like time-of-day (F RUN and not REC RUN). Rather than use the actual time of day, you might consider setting the timecode numbers to start rolling at 01 hours (01:00:00:00) at the start of each day to avoid getting repeated numbers during the course of a single shooting day i.e. after midnight.

Important: A 10 second pre-roll is needed for all camera/audio start ups. The 10 second pre-roll is required by ONLINE assembly systems.

When the camcorders are powered down and then back up again (for example, when changing batteries or breaking for lunch), there is the possibility for the timecode generators to get out of sync with each other. So it may be necessary to re-jam the timecode every time one of the camcorders is powered up again.

Advantages: Apart from temporary jamming cables, no cables are needed during shooting to connect the camcorders and DAT apart from the normal audio feeds and monitor return (that can be radio linked if required). No special equipment needed, like external timecode locking boxes. A ‘Smart Slate' is optional.

Disadvantages: Slating is necessary, although a simple non-timecode slate can be used. Periodic jamming of the system is necessary. Also every time one of the camcorders is powered up. Need a 10 second pre-roll on all camera/audio start ups. Must use continuous-running, F RUN timecode. The timecode reference between image and sound only matches on the whole seconds. There can be up to a single frame discrepancy between the camcorders used in the system.

*******The following options require special timecode conversion boxes*******

(6). Record 29.97 Timecode onto Camera Audio Track

Record 29.97 timecode from a Denecke or Ambient timecode generator (than has been jammed to the DAT master recorder at 29.97 Non Drop Frame), onto audio track #2 of the CineAlta camcorder. The timecode generator is attached to the outside of the camcorder by velcro or tape. The 24p HD camcorder records 23.976 timecode in the normal way with picture.

The Avid can read the timecode on the audio track ("Audio as TC") into the EDL to facilitate auto-conforming. In this case, the DAT becomes the master audio recorder. Audio track #1 on the camcorder is used to record backup audio for the production.

Advantages: A way to auto-conform the audio in post. Slating is not absolutely required, unless for safety reasons or simple identification of shots. The DAT now becomes the master audio recorder, and not the camcorder as above. This gives a measure of control back to the location sound mixer, as they now control the master audio recorder for checking and monitoring purposes. Independent recording of wild sound between camera takes is also now possible.

Disadvantages: Only one track available for location backup audio (unless using the HDCA-901adapter to access audio tracks #3 and #4). This technique is a little awkward to use in practice, as skill and time is needed to conform the audio in an Avid editing system (or similar).

(7). Camera as master 23.976 - Cross Jam DAT to 29.97

Connect a timecode generator (Denecke or Ambient) to the 23.976 timecode output of the 24p HD camcorder. The Denecke or Ambient unit cross jams the 23.967 timecode and locks it to 29.97 timecode in a fixed relationship. Then jam the DAT to this timecode generator unit which is now running at 29.97. The timecode numbers will now match perfectly on both the picture and audio, but only on the first frame of every second. i.e. timecode numbers with corresponding hours, minutes, seconds, and "00" frame numbers will match. But the timecode numbers will not match exactly until the next "00" frame numbers come around once again, one second later. Normal slating is optional, and a timecode slate is also optional.

As a safety measure, you can show a slate to camera which has been jammed to the 29.97 timecode, and/or simply clap in the normal way.

Important: With every camera battery change (or whenever the camera is powered down and back up again), a break in timecode of up to about 7 frames occurs!!!! To correct for this you need to:

(1) Re-jam the Denecke or Ambient unit to the camera's 23.976 timecode output (usually by turning it OFF, then back ON again).

Plus (2) re-jam the DAT to re-established the 29.97 timecode output of the timecode generator unit.

Finally, (3) re-jam the Timecode slate to the re-established the 29.97 timecode of the system.

Continuous running, or time-of-day, timecode must be used (not REC RUN). And very importantly, the production must be disciplined about pre-rolling for 10 seconds before the slate (or calling "action"). This is needed for pre-roll by the final On-Line Assembly system in the final stages of post.

Advantages: Picture and Audio timecode will match (but only the first frame of every second), so slating is optional. No permanent connect of camcorder and DAT (just a momentary connection for jamming). Works with just a single Denecke or Ambient generator unit (rather than multiple units).

Disadvantages: The timecode between machines (camera/DAT/Slate) can get out of step when the camera is powered down (up to about 7 frames)!!! So a multi-step re-jamming process is required with every camera battery change (or whenever camera is powered down and back up again). The method is prone to timecode mismatching if something is forgotten, or goes wrong, during the numerous re-jamming operations throughout the day. Extreme care needs to be taken to make this method reliable. Can not use REC-RUN timecode with this method.

(8). Evertz Afterburner to convert Timecode

Use he Evertz HD Production Afterburner (models HD9155, HD9155-AUD, HD9155Q, HD9155Q-AUD) to continuously translate 23.976 timecode coming from the camcorder to 29.97 timecode. A cable connection between the camcorder and Afterburner is required. When hard-wired to the DAT, the Afterburner provides a constant 29.97 reference, thus eliminating loss of timecode synchronisation with camcorder battery changes, and/or rebooting the camcorder.

The Afterburner can also perform a simultaneous downconversion to standard NTSC video, which is not a real-time process. However, the converted timecode is delayed the appropriate amount to keep it in step with the downconverted video (see method #12 below). Care needs to be taken with any delay issues when using the Evertz Afterburner. Any offset in the system (usually 4 or 5 frames) is always in a fixed relationship, and can be easily re-established in post if and where necessary.

It is also possible to jam the timecode to the DAT recorder, and then disconnect the cable for greater freedom in shooting. But in that case, you need to re-jam the timecode every time the camcorder is powered down and back up again (as in method #6 above).

Advantages: Provided you maintain the timecode cable connections, there is no loss of timecode synchronization with periodic battery changes, and/or rebooting of the camcorder.

Disadvantages: The Afterburner is a mains-power operated unit (110 volts) and not battery operated. So the system is tied to a mains-electricity source. Cables are required for timecode between the camcorder, Afterburner, and the DAT (unless only jamming timecode after camera reboots). There may be constant offsets to deal with in post if using the downconverted NTSC video (depending on the configuration).

(9). DAT as the Master Timecode Generator + "Lockit" boxes

In many of the above methods, the 24p camcorder provides the master timecode reference at 23.976. But you can also make the DAT the master timecode reference source running at 29.97. Use a sync Box from Denecke SB-2 or Ambient Clockit ACL-202 mounted on the camcorder. These ‘boxes' are cross jammed to the 29.97 timecode from the DAT, but output 23.96 timecode in step with the original 29.97 source. The CineAlta can lock to this external timecode reference when connected to the camcorder's timecode input ( "TC-IN" via a BNC connector).

NOTE: In a multi-camera set up, it is possible that the cameras might be out of sync with each other, by up to one frame. The reason is because this method is a simple timecode jamming process, and is therefore independent of the camcorder's internal sync. The moment of jamming can occur at slightly different times within the camcorder's recording cycle, thus creating a possible offset of up to a single-frame discrepancy between two or more camcorders in a multi-camera set up. This problem can be overcome by feeding all camcorders identical timecode that is referenced to an external sync generator. See method #13.

Advantages: There is no loss of timecode synchronisation with periodic battery changes, or rebooting of the camcorders. Picture and Audio timecode will match (but only the first frame of every second), so slating is optional. No permanent connection of camcorder and DAT is required, just a momentary connection for jamming.

Disadvantages: There can be a timecode offset with multi-camera set ups. HDCAM's need to reference to Tri-level sync, so this method is more precise when using the latest Tri-level Lockit boxes designed specifically for HD. See method #12.

(10). HD Camcorder as Master Timecode Generator

This method is also suitable for multiple camera setups. It uses one of the camcorders as the master timecode generator running at 23.976. Use an (audio) Distribution Amplifier (DA) to split the timecode coming from the master timecode generator running on the ‘master' camcorder into several channels to allow it to be sent to the other camcorders, and also the audio station. For the additional camcorders, connect (hard wire) the TC-OUT from the ‘master' camcorder to constantly jam the timecode on the other camcorders (TC-OUT, via the DA, to TC-IN).

For the audio, an additional split from the master timecode (via the DA) can be used to jam a second timecode generator, such as a Evertz model 5010. Use this unit to send out a second timecode stream at 29.97 (Non-Drop-Frame preferred) to the DAT recorder, or DA88 etc. A timecode slate can be jammed periodically to display either 23.976 or 29.97 timecode numbers to the cameras. Usually, 29.97 is preferred on the slate, as it gives a direct reference back to the external, or double-system audio, rather than picture. However, 23.976 could be used for the slate, but this practice would be unusual.

Any of the camcorders, or the DAT itself, can be designated as the master audio recorder, or the back up audio recorder, as required. Usually, one (or even all of the camcorders) serve as the master audio recorder to make things easier and more straight forward in post.

Advantages: Provided you maintain the timecode cable connections, there is no loss of timecode synchronization with periodic battery changes, or rebooting of the camcorders. Picture and Audio timecode will match (but only the first frame of every second), so slating is optional. Because everything is hardwired, no need for constant jamming of the system (apart from the timecode slate, although this can also be hard wired, or radio linked, if desired.). You can shoot with any one of the camcorders by itself, provided the "Master Timecode" camcorder is powered up and sending out timecode to the entire system, even if it is not recording image or sound itself. There is flexibility in assigning which is the master, and which is the backup, audio recorder.

(11). Using an external Timecode Generator

This method is also good for multiple camera setups. It uses an external master timecode generator, such as the rack-mounted Evertz model 5010-24p, running at 23.976. Check carefully to make sure the particular Evertz 5010 model employed is capable of generating 23.976 timecode, and not just pure 24 timecode. The latter will result in repeated timecode errors and the general failure of this system. The 23.976 timecode is sent via cable to each camcorder. Use a Distribution Amplifier (DA) to divide the timecode from the master Evertz timecode generator, so it can be sent to each camcorder (DA-OUT to the camera's TC-IN).

An additional split from the Distribution Amplifier can be used to jam a second timecode generator, such as a Evertz model 5010, set to generate 29.97 timecode. The 23.976 timecode is constantly jammed to the newly generated 29.97 (Non-Drop-Frame timecode is preferred), which is sent to the DAT recorder, or DA88 etc. in the audio station.

A timecode slate can be jammed periodically to display either 23.976 or 29.97 timecode numbers to the cameras during the normal slating operation. The choice is not critical, as the only true cross-reference for editing is on the whole seconds only i.e. timecode numbers with corresponding hours, minutes, seconds, and "00" frame numbers will match. But the timecode numbers will not match exactly until the next "00" frame numbers come around once again, one second later.

You must use continuous timecode, like time-of-day (not REC RUN). Rather than use the actual time of day, you might consider setting the timecode numbers to start rolling at 01 hours (01:00:00:00) at the start of each day to avoid getting repeated numbers during the course of a single shooting day i.e. after midnight.

Advantages: Provided you maintain the timecode cable connection, there is no loss of timecode synchronisation with periodic battery changes, or rebooting of the camcorders. Picture and Audio timecode will match (but only the first frame of every second), so slating is optional. Because everything is hardwired, no need for constant jamming of the system (apart from the timecode slate, although this can also be hard wired, or radio linked, if desired.). You can shoot with any one of the camcorders on its own, without the other camcorders being powered up.

Disadvantages: Can't use REC-RUN timecode, only continuous running or time-of-day timecode. Need a 10 second pre-roll on all camera/audio start ups. Separation of the camcorders is limited to the length of the timecode cabling in the system. The Evertz 5010 boxes are mains power operated units (110 volts) and not battery operated, so the system is tied to mains power, or an on-set generator. Need slightly different models of Evertz boxes in this set up, one optimized for 23.976, and the other for 29.97. Particular care needs to be taken with the selection of these Evertz boxes.

(12). Clockit / Lockit System

vThis method is also good for multiple camera setups. It uses an external master timecode generator running at 23.976, such as the Ambient Clockit Controller ACC 101 Mark 2. The master Clockit is used to jam individual Ambient Lockit synchroniser ACL 202 units. The battery-operated Lockits are taped or attached by velcro to the camcorders, and connected to the camcorder's timecode input ("TC-IN" via a BNC connector). One Lockit unit is needed per camcorder, plus an additional Lockit for the audio station.

These units are stable enough so that re-jamming should only necessary 2 or 3 times during the course of a normal shooting day, or about every four hours (although the system can be re-jammed as often as you like, for added confidence). The camcorder Lockits are set to run at 23.976. The Locket for the audio station is set to run at 29.97 (Non Drop Frame preferred) and connected to the DAT recorder, or DA88 etc.

The slate can be jammed periodically from any of the timecode generators, and can be set to run at 23.976 or 29.97 (Non-Drop-Frame preferred) as desired.

After the camera/s roll, the timecode slate can show either 23.976 or 29.97 timecode numbers to the cameras during the normal slating operation. The choice is not critical, as the only true cross-reference for editing is on the whole seconds only i.e. timecode numbers with corresponding hours, minutes, seconds, and "00" frame numbers will match. But the timecode numbers will not match exactly until the next "00" frame numbers come around once again, one second later. Usually 29.97 is preferred, as it gives a direct reference back to the external or double-system audio, rather than picture.

Advantages: There is no loss of timecode synchronisation with periodic battery changes, or rebooting of the camcorders. Picture and Audio timecode will match (but only the first frame of every second), so slating is optional. Only infrequent jamming of the system is required (the timecode slate can be hard wired, or radio linked, if desired.). You can shoot with any of the camcorders independently of the others. Camera placement is not limited by timecode cabling. All units are battery operated, making the overall timecode system independent of mains electricity or on-set electricity generators.

Disadvantages: Can't use REC-RUN timecode, only continuous running or time-of-day timecode. Need a 10 second pre-roll on all camera/audio start ups. Dependent on a number of independent crystals for keeping perfect sync across the entire system, so periodic checking of the system for its integrity is needed to check for any drift. A number of batteries (usually AA's) need to be changed regularly during the production (usually daily).

(13). "Lockit" boxes with Tri-level Sync

In a multi-camera set up, it is possible that the cameras might be out of sync with each other, by up to one frame. This is because the above method is a simple timecode jamming system, and is therefore independent of the camcorder's internal sync cycle. The moment of jamming can occur at slightly different times within the camcorder's recording cycle, thus creating a possible offset of up to a single-frame discrepancy between two or more camcorders in a multi-camera set up. This problem can be overcome by feeding all camcorders identical timecode that is referenced (or locked) to an external Tri-level sync generator.

This method is identical to method #11 described above, but uses a later generation of "Lockit" box equipped with a Tri-level sync generator in addition to the normal timecode generator. The latest generations of the Ambient Lockit box, namely ACL-202T, and also the Denecke SB-T Tri-level Syncbox, now has an output for Tri-level sync. Both the timecode and the Tri-level sync are fed to the Sony HDCAM using two short linking cables connected to "Timecode In" and "Genlock" respectively.

What is Tri-level sync?

The sync reference going to a camera defines when each frame begins to scan, in fact, when each line in each frame begins to scan, as it builds the entire video image. For NTSC analog video, the sync signal consists of a Blanking Pulse (sync pulse + color burst + "back porch") followed by the video image data. This sync information is repeated every scan line.

However, High Definition camcorders can not genlock or reference to a standard NTSC or PAL video sync signal. Rather, it uses a another type of sync called Tri-level sync. It basically works in the same way as analog sync, but it is structured differently. With Tri-level sync, the signal consists of a three-level sync pulse (zero volts (0V) Blank, -0.3 V pulse, +0.3 V pulse) followed by the video image data. Like analog sync, the signal is repeated every scan line as it creates an entire HD video frame. So in the High Definition world, we need to genlock with what is known as Tri-level sync.

Tri-level Sync Formats?

The Ambient ACL 202T "Lockit" box generates Tri-level sync in accordance with the SMPTE 274 - 1998 and ITU-R.BT.709-4 international standards. And likewise, the new Deneke SB-T Tri-level Syncbox generates Tri-level sync for all 1920(H) x 1080(V) formats.

However, the Panasonic Varicam is looking for an external Tri-level sync source compliant with the SMPTE 296M standard and compatible with 1280(H) x 720(V) formats. This is the type of Tri-level sync used by the Varicam family of High Definition camcorders, namely the Panasonic AJ-HDC27V, Panasonic AJ-HDC27V-M1 (upgrade), and the newest Panasonic AJ-HDC27F. The Ambient Tri-level "Lockit" box will work with the Panasonic Varicam, provided you set the dip switches to output the appropriate format of Tri-level sync (i.e. for SMPTE 296M). Here is the correct dip switch configuration for the Ambient "Lockit" box when shooting with the Panasonic Varicam.

(A) For 23.976 timecode with 59.94p Tri-level sync in the Varicam:
Dip switches #1 ON, #2 OFF, #3 ON, #4 OFF, #5 OFF, #6 OFF, and #7 OFF

(B) For 29.97 timecode with 59.94p Tri-level sync in the Varicam:
Dip switches #1 ON, #2 ON, #3 OFF, #4 OFF, #5 OFF, #6 OFF, and #7 OFF

(NOTE: If you set dip switch #3 ON, then you will get Drop Frame timecode, but Non-drop timecode is normally preferred, so normally leave dip switch #3 OFF)

Both the "Lockit" boxes mentioned above are fully compatible with Sony HDW-F900 camcorders.

Advantages: Complete frame accuracy across all camcorders is now possible in a multi-camera set up.

Disadvantages: Can't use REC-RUN timecode, only continuous running or time-of-day timecode. Need a 10 second pre-roll on all camera/audio start ups. If there is any interruption to the external Tri-level sync fed to the camcorder, a green masking frame is inserted whenever there is not enough information to build and display a normal frame of image. The problem is made worse by say, an intermittent problem in a faulty cable or connector, that causes the system to flip flop back and forth between internal and external. So if any interruptions to the Tri-level sync feed is not detected and corrected at the time of shooting, the editor may be presented with unsalvageable material in post. Special care needs to be taken to make sure all external sync feeds are 100% clean and 100% continuous to avoid possible "green hickup" problems. The sort of things that can cause an interruption to the sync feed is, for example, a failing battery in the Ambient or Denecke Tri-level "Lockit" box, or a faulty cable or connector, or similar.

(14). Using DVCAM as the backup, or master, audio recorder

This is perhaps the most unusual configuration. The idea is to use a standard-definition digital video recorder, such as DVCAM, as the backup audio recorder. This not only allows the recording of backup audio, but the system can also simultaneously record downconverted NTSC picture, along with the 29.97 (Non Drop Frame) timecode, all at the same time. The resulting picture, audio, and the timecode are in sync with each other (although possibly offset).

This eliminates the need to downconvert the camera-original HDCAM tapes as an additional post-production step later on. It also eliminates the need to sync up double-system sound, as with some of the other methods described above. The system has the advantage that the DVCAM tapes can be taken directly from the set and immediately loaded into a non linear editing system (such as an Avid), thus saving time, and improving overall efficiency. There may also be a cost saving in doing this as well.

Additionally, it is possible for editing to be performed concurrently with the actual shooting. If needed, a rough edit of a particular scene could be performed to check for specific problems before striking the set up, and moving onto the next scene.

As with method #7, the Evertz Afterburner model HD9150 is used to continuously translate 23.976 timecode from the camcorder to 29.97 timecode. When hard-wired to the DVCAM recorder, the Afterburner provides a constant 29.97 reference, thus eliminating loss of timecode synchronisation with camcorder battery changes, and/or rebooting the camcorder.

The Evertz HD Production Afterburner (models HD9155, HD9155-AUD, HD9155Q, HD9155Q-AUD) is also used to simultaneously downconvert the HD stream to NTSC video. As we saw the before, this is not a real-time conversion process (..... almost, but not quite). There is a fixed delay of the NTSC video that is output from the Evertz Afterburner. It is usually about 4 or 5 frames, or about one fifth of a second.

This means the audio can be slightly out of step with the picture with some downconverter models. This fixed offset in sync can be easily re-established in the post. Or alternatively, additional hardware can be employed to delay the audio to keep them in step with the recorded NTSC video.

However, the Evertz HD "Production" Afterburner models, HD9155-AUD, HD9155Q-AUD, and also the Afterburner "Post Slate" series, HD9150PS-AUD, HD9150QPS-AUD, have the ability to de-embed audio from the incoming HD bitstream, and delay it so that it is in time with the output video and timecode from the downconverter. Audio is output as two AES streams, or four balanced analog audio signals. It also has a front-panel headphone jack for monitoring the audio with volume control and channel select. These models take care of all time-delay issues.

DVCAM is an obvious choice as a suitable recorder for this purpose. Suitable DVCAM decks with timecode inputs, can be rented or purchased at an affordable price for most productions. Both picture and sound quality are quite adequate for this application. The deck provides a Betacam SP level of image quality, plus two discreet 16-bit 48KHz audio tracks. In short, perfect for most non-linear editing systems. The video and audio can simply be ‘captured' to the hard drives via a Firewire IEEE1394 connection. Or fed in and re-digitized in the editing system according the compression scheme it uses (M-JPEG, MPEG-2 etc.).

A suitable field recorder is the portable Sony DSR-50 ($4000). It has XLR connectors, timecode input/outputs, and it even has an LCD for viewing image. And of course, two discreet channels of 16-bit, 48KHz audio.

A variation of this approach is to make the DVCAM the master audio recorder. If you now make the 24p camcorder audio the backup system, then the sound recordist would have full control over monitoring, mixing, and playback of the master-audio recording machine. This basic control has been lost to the location sound mixer with many of the systems described above. The sending of master audio to the 24p camcorder means the master recorder is out of the hands of the sound department. They can't see the meters, the return audio from the camcorder is low quality, and they can't play back the audio master without interrupting the production, or annoying a busy camera team, or video tech, going about their jobs.

Wild sound is another issue to take into consideration. If the master audio is recorded on the 24p camcorder, either the camera has to be tied up for wild sound, or a second system such as DAT must be used. This is more equipment to rent, plus it can complicate digitizing and logging later on. But on the other hand, if wild tracks were recorded on the same tape as the video downconversion (i.e. the DVCAM tape), life would be simpler in the edit bay. Since it would be all on the same DVCAM tape, it would be much easier to transfer the occasional audio grab, or sound effect and so on, that is captured on-the-fly between the times the camera is actually rolling for picture.

Perhaps most importantly, when the audio department is in control of the master audio recorder, they would have the normal level of independence on the set. This would help them greatly in getting their job done properly and efficiently, and with the highest possible audio standards of their craft.

Advantages: Save time and money on downconverted NTSC video dubs and unnecessary syncing for post. Gives a large measure of independence and control back to the sound department.

Disadvantages: Requires more equipment ("Afterburner" and additional DVCAM deck, or similar). The configuration may be too expensive for a multi-camera production (compared to sending the HDCAM tapes out to a normal downconversion facility)? The "Afterburner" needs a mains power supply (110 volts). Also there can be delay issues with the "Afterburner" to deal with i.e. the audio needs to be delayed a fixed amount to stay in perfect sync with the downconverted image and timecode (unless using model HD9155Q-AUD) . This requires yet another box, or additional manipulation in post. The system needs cable connections between equipment......so not suitable for documentary style of shooting, but usually works for location or studio-based drama.

(15). DVCAM as audio recorder with new Miranda box

Very similar to method #12 above, but replaces the Evertz Afterburner with the new Miranda DVC-800 onboard downconverter attachment. The new Miranda unit mounts between the camcorder and the battery on the both the Sony HDW-F900 and the Panasonic AJ-HDC27V camcorders. The Miranda's outputs include HD-SDI, regular SDI, composite video, and DV via a IEEE1394 FireWire interface. Significantly, the FireWire port delivers embedded audio and timecode as part of the DV video stream (also metadata).

The FireWire signal can be recorded to either a DV or DVCAM deck, or directly to a fixed or removable computer Hard Disk Drive. Either way, the video can be quickly and efficiently loaded into a non-linear editing system. It can be loaded in real time in the case of DVCAM playback, or perhaps even faster using the Hard Disk Drive option.

It would appear that all time-delay offset problems with the audio and timecode are eliminated with this system, although this new system is yet to be field tested (the new Miranda unit was announced in October, 2002).

On the face of things, it seems like a superior system to the Evertz Afterburner method #12 above. Also the output cabling is reduced by using a single FireWire cable. A much wider range of recorders are now possible, provided they have a FireWire input. And even a DVD-R or DVD+R real-time recorder could be used to provide client, or producer/director/cast/crew dailies. A DVD disk is a convenient way of presenting dailies, and has adequate quality to do justice to the production by not giving a distorted impression of the quality of the work coming from the set.

The audio and the timecode is a direct copy of that coming from the camcorder itself. Although it provides a source of backup audio, it does not do it independently of the HD camcorder. In this case, the backup audio is in series, and downstream, from the master audio recorder. As it is not an independent system, it is not as ‘safe' as a backup recording to a separate DAT recorder. Although, this begs the question of how many independent backup audio recordings are really required on a set? This degree of backup of the audio was not common practice for film-style productions in the past, so maybe this is a somewhat over cautious practice for HD production as well. The key to this particular issues is perhaps more about thoroughly monitoring the integrity of master recording, rather than getting overly concerned about making additional backups. But I do respect the differing points of view in respect these issues. When all factors is taken into consideration, there are no easy, obvious, or straight forward answers.

Of course, the audio can be sent independently to the DVCAM recorder as in method #12 above, and not via the camcorder. Plus 29.97 (Non Drop Frame) timecode can be recorded from a additional timecode generator that is jammed to the camera's 23.976 timecode output. You can even make the DVCAM the master audio recorder, as before. By doing these things, you can maximize the advantages found in this particular method with those from method #12 above.

Advantages: Save time and money on downconverted NTSC video dubs and syncing up the audio in the post. Direct recording to Hard Disk Drives in a computer may be possible. Audio and timecode offset issues may no longer apply. Can give a large degree of independence and control back to the sound department, if the additional video recorder is made the master audio recorder.

Disadvantages: Requires more equipment, namely the new Miranda box and additional DVCAM deck (and/or computer). The new Miranda downconverter may take some time to be become widely available? Needs more cable connections between equipment, and possible mains power......so not suitable for documentary style of shooting, but is usually suitable for location or studio-based drama.

(16) True "Film-style" Double-System Production

This method emulates the normal procedure used for double-system recording on film shoots. This type of true, independent, double-system recording gives ultimate autonomy and control to the sound department. This is its most significant advantage. The highest-quality audio and the most professional result is now possible with this method.

There are no cable connections from the audio department to the HD camcorder/s whatsoever. In fact, no audio is recorded on the HD camcorder/s themselves. The master audio recorder is a DAT, or hard-disk recorder, or similar high-quality, professional, audio recorder. If backup audio is required, then it can be simultaneously recorded to a second audio recorder installed in the audio station, like a second DAT, or hard-disk recorder etc.

The whole system needs to be referenced to the same timecode. To eliminate cabling, it is common to use "Lockit" boxes like the ones discussed earlier from Denecke and Ambient, namely the Ambient Lockit box ACL-202, and the Denecke SB-2 box. It is also possible to mix these "Lockit" boxes from the two different manufacturers, and also different models of these "Lockit" boxes depending on the application i.e Tri-level boxes with standard timecode boxes.

If it is a multi-camera shoot, it is desirable to have the newer Tri-level "Lockit" boxes feeding the camcorders, such as the Ambient Lockit box ACL-202T, or the Denecke SB-T Tri-level Syncbox. As discussed earlier, these Tri-level boxes keep the timecode in step with camera sync, and therefore provide absolute frame-accurate sync in respect to each other. As discussed before, great care needs to be taken to maintain the absolute integrity of the external sync feeds to the camcorder/s.

This method may employ some system to automate the procedure for syncing up dailies in the post house later, such as the Catch-24 system. But this is optional, because this can always be done manually (although more slowly and laboriously).

Normally you will need a Tri-level box on each camcorder, a standard timecode "Lockit" feeding the Catch-24 computer (if used), and the internal timecode generators built into the master and backup audio recorders, and of course, the timecode slate. But the precise configuration my vary from production to production.

The master timecode source could be any stable timecode generator used in the system, for example, the timecode generator in the master audio recorder. The master timecode source is used to jam timecode in all the portable "Lockit" boxes used across the entire system. However, it is usually more convenient to use a free-standing, portable master time code generator, such as the Ambient Clockit Controller ACC 101 (Mark 2), or Denecke GR-1. These units can be easily carried around the set to re-jam all the "Lockit" boxes about every 4 hours, or whatever interval is deemed appropriate to eliminate the effect of the crystals drifting significantly from one another in the system.

As with the other "Lockit" systems, you must use continuous timecode, like time-of-day (not REC RUN). Rather than use the actual time of day, you might consider setting the timecode numbers to start rolling at 01 hours (01:00:00:00) at the start of each day to avoid getting repeated numbers during the course of a single shooting day i.e. after midnight.

While slating is not absolutely necessary, it is probably a good idea to slate each shot for reasons of safety. Also, if using the Catch-24 system, the Catch-24 operator uses the moment of slating to capture the timecode that will be ultimately used in the flex file used to automatically sync everything up later.

More about the Catch-24 System:

The Catch-24 system was developed by Roger Mayer, the chief engineer at Level 3 Post in Burbank. He also wrote the software used at the heart of this system. It is an automated system for finding selected takes on a camera original tape, and then syncing those specific takes up with double-system audio supplied on a separate tape. Because the system is highly automated, it saves significant time and money in getting material ready for the editing room.

In essence, the software simply captures the timecode number at the precise moment a key is pressed on the computer keyboard. An operator on set, has the responsibility of capturing the timecode number at the beginning of each shot, usually just before the slate. And similarly, the ending timecode is captured into the system after the director calls "cut". This provides a timecode "in" and "out" reference point for each shot. The operator also enters the slate numbers pertaining to each shot, and indicates "OK" or "circled takes" that will be ultimately sent to the editor. Non-essential material can be eliminated in this process i.e. "NG" takes. This process generates something like an Edit Decision List, or EDL style of list, which is a record of all this information accumulated throughout the shooting day.

At the end of the shooting day, the Catch-24 operator generates a flex file containing all this information. It is recorded onto a floppy disk in the computer. The floppy disk is shipped, together with the original sound and camera tapes, to the transfer house. At the transfer bay, the flex file is loaded into the telecine edit controller, where it is used to control an automated function to synchronize picture and sound on "circled takes" or selected takes only. The resulting marriage is cloned to a new master tape in the case of HD, and/or downconverted to an SD master tape, depending on the requirements of the production The basic idea behind the Catch-24 system is to save considerable time performing this operation, and therefore makes the syncing up of double-system audio far more speedy and economical.

Roger Mayer's Catch-24 system is basically an in-house system used by the LIBERTY LIVEWIRE group of companies, now renamed ASCENT. They own a large number of post houses nationwide, including the following that offer this service in the Los Angeles area:

(1) ENCORE VIDEO - HOLLYWOOD. telephone: (323) 466-7663

(2) HOLLYWOOD DIGITAL. telephone: (323) 468-5450 or (310) 664-3516

(3) LEVEL 3 POST - BURBANK. telephone: (818) 840-7200

These companies will loan you the Catch-24 system for free for the duration of your shoot, provided. of course, you are having your post work done with one of their companies. It consists of a notebook computer, the Catch 24 software (DOS based), and a Miranda timecoder reader interface to the computer. They also give your operator a little training session (takes 15 minutes or so) before they go out with the system for the first time.

The system requires the Deneke or Ambient "Lockit" box plus the Miranda "Little Red" LTC Timecode Reader (BNC to RS 232 - serial - computer interface). And of course the DOS-based Catch 24 software and a portable computer. The Post House will lend a production everything required by the system, except the actual "Lockit" boxes.

Advantages: Gives complete autonomy to the sound team enabling them to deliver the most professional result. True confidence monitoring of the audio is now possible. Plus monitoring is now possible with a significantly higher-quality signal, seeing the noisy camcorder audio monitoring system is eliminated. Earlier recordings can be easily replayed for checking purposes. Wild sound, and other sound grabs, can be easily recorded without the need for the camcorder/s to be rolling. If using the Catch-24 system, "NG" takes can be easily discarded and not take up unnecessary space in the non-linear editing computer.

Disadvantages: Must use continuous timecode, like time-of-day (not REC RUN). The audio needs to be sunk up to picture, so an additional step in post, and therefore an additional expense for the production. If using external Tri-level sync, there is a greater risk of green masking frame (or "green hickup") problems. Great care, and careful monitoring, needs to be taken when genlocking with external Tri-level sync feeds.

The Future:

In closing, it will be interesting to see what ends up being the standard production procedure in the long run. It seems overly complicated and cumbersome right now, but I'm sure it will eventually settle down to a relatively straight forward system that will be widely used in the industry. Once there is a standard approach (or approaches) to these issues, everything will be much plainer sailing.

Peter Gray
(near Los Angeles)
P.O. Box 5132
Pine Mountain Club, CA 93222
United States of America
telephone: +1(661) 242-1234

dp@petergray.org