GB2189037A - Improvements in editing to produce an edited videotape - Google Patents

Abstract

Cinematographic film is provided with a frame count in a code similar to a vertical interval time code (VITC) at the top of each frame in an area which is within but at a marginal portion of the in-vision frame area. When a videotape is generated from this film, a VITC reader 54 reads the VITC from each frame and a change detector 56 identifies discontinuities in the frame count caused by edit points. The frame counts to either side of the edit points are stored as an edit listing by an auto data logger 58. <IMAGE>

Description

SPECIFICATION Improvements in editing to produce an edited video tape This invention is concerned with various aspects of editing source material on video tape or film to produce a video tape.

One improvement on the well-known operations has been described in British Patent 2,101,789. The present invention is concerned with an alternative improvement which enables greater automation to be introduced into the labour-intensive final editing operations.

When it is required to make a programme for broadcast purposes or a videotape for sale as such, it is commonly found that the source material exists in a variety of formats. Some may already be in videotape form, whereas other parts may be on cinematograph film of any of a variety of gauges. To produce a final videotape it might be thought that the simple solution would be to transfer all the original material to videotape and then edit the videotape by recording the desired sections from one videotape machine to another.

In actual fact it is extremely difficult to edit any but the very simplest of programes in this way. If it is appreciated that a typical broadcast programme will involve several hundred edits, it will be seen that it is very much easier in practice to work with film material than with videotape. Film can be physically spliced, and can be adequately identified just by looking at it. It is much easier to select the desired parts of the film, cut them out as you come to them, hang them on the cutting room wall, and re-assembly them in the required order, than if ever would be to execute the corresponding operations in videotape.

Other reasons for working with film rather than videotape are that much film editing equipment already exists and operators are experienced in using it, and also the soundtrack is more easily handled by conventional dubbing processes if film is used.

The conventional editing studio thus uses film as the editing material. A flow chart of a typical broadcast editing studio is shown in Fig. 1. In outline, the operations are as follows. Source material is received as 8mm, 16mm or 35mm film or videotape in various formats as shown at 10. The source material is transferred to standard videotape to produce master compilation videotape reels as shown at 12. These tapes include a time code (T/C) marking which is either generated at 14 or is generated in the videotape machine and extracted at 14. What happens to this time code is described in more detail below.

From the master compilation videotape reels a working print is made on 16mm cinematographic film as shown at 16. This film can be a black-and-white print and need not be of broadcast quality. The editing operations 18 are then conducted on this film material in well known manner. After the editing operation is completed on this cutting copy of the material, a final work print may be obtained. This is also not of broadcast quality.

What now needs to be done is to go back to the master compilation videotape reels and to select those parts of the original material which have been retained in the work print and to produce a final broadcast-quality videotape from them. This operation is known as the conforming operation as the videotape is conformed to the content of the final work print, as shown at 20 in Fig. 1.

It will be appreciated that we now need a way of identifying which parts of the original material, held in the master VT reels, have been incorporated in the work print. This is where the time code is used. The time code uniquely identifies each frame of the 16mm material, and is added to the signal from the master compilation videotape machine 12 in a step 22. The time code thus survives the editing operation and will appear in the work print obtained after editing.

The work print is then viewed frame by frame to detect edits and a manual log of the frames where edits occur and the time code appropriate to those frames is obtained as indicated at 24. In order for the time code to survive the editing operation it has to be in the visible area of the film, and to make it easily readable it has to occupy quite a large and significant portion of the film area. Fig. 3 illustrates very diagrammatically a frame 26 of the work print illustrating the time code 28 in its usual position. In addition to the time code, the master VT spool number can be included on the cutting copy of the film such as by a "paddle" inserted into the bottom left hand corner of the film frame when in the projector. Thus the relationship between the compiled master videotape reels and the edited film to be conformed from those master reels is by means of in-vision time code.At present this data is retrieved for entry into the conforming edit system by pen and paper, possibly assisted by manual entry into a micro computer storage system. These are time consuming processes, which still necessitate manual conforming edit point location on the final edit tape.

Another disadvantage of this system, apart from its laborious logging procedures, is the presence of the in-vision time code data, eliminating much of the lower third of the picture information which is required by the film editor and production team. Furthermore, the videotape spool number, if included at all, is only incorporated by a rather inconvenient procedure.

Semi-automated systems for film conforming already exist. For instance, one system correlates the compilation master tape reel time codes to the transferred 16mm film cutting copy edge numbers which exist along the edge of the film (see e.g. British Patent 2,102,139). After film editing, these edge numbers are fed by a manually driven system into a computer that can relate them to their time codes ready for entry into the conforming system. Master VT compilation reels can be identified by the use of the unique spool codes. However, any entry error, slip or computer problem at this or previous stages, damages or destroys all cross-references between the edited film and its source master compilation reels. for this reason this system retains the intruding in-vision time code on the lower third of the picture.

Fig. 1 illustrates one way in which the conforming process can be conveniently achieved in the conventional system. The work print is transferred to videotape at 30 in a telecine to produce a final videotape 32 to be conformed.

A time code generator 34 adds a further time code to this in conventional manner such as by using vertical interval time code (VITC) in accordance with EBU Standard No. TECH.

3097-E, 3rd Edition, April 1982. This VITC code defines the points in the work print at which the various sections of original material need to be inserted and are entered manually at 36 with the manual data log 24 into the final edit control system 38. This system conforms the final tape in broadcast-quality colour from the black and white edited videotape 32 with the aid of the videotape recorder 20. The resultant videotape can then be transmitted as at 40.

Known methods can be employed to take account of the fact that the PAL television system comprises periodic cycles extending over more than one frame, and in particular has even and odd frames such that the final signal should always maintain the even-odd alternation. The PAL sequence can be worked out from the time code.

Various ancillary operations can be achieved and are not described here in detail. Film dubbing 42 is achieved at the same time as the editing takes place. Some specially shot 16mm film may be directly available and this can be used for editing without having to produce an inferior quality black and white print.

In the final conforming stage graphics can be added and controls can be provided to produce effects other than a simple cut, such as a dissolve or fade for example. Special effects 44 can also be introduced in the formation 12 of the master compilation videotapes.

The present invention is defined in the appended claims to which reference should now be made. One example of the invention will now be described in detail.

Figure 2 shows a flow chart/block diagram similar to Fig. 1 of a system embodying the invention, and Figure 4 is a view similar to Fig. 3 of a frame of the cutting copy of the film used for editing. Those parts of the system which are similar to Fig. 1 carry the same reference numerals and are not described again in detail.

In Fig. 2, master compilation videotapes are produced at 12 as before but when the cutting copy of the film is made from these tapes the frame count is inserted in a different way than hitherto. Instead of the visible frame count in the centre of the frame, we introduce a machine-readable code which, while being in the frame area, is at a marginal portion of the frame area so that it does not significantly interfere with the viewing of the scene. As shown in Fig. 4, our preferred code 50 is carried at the top of the frame area, and occupies about 4 to 8 lines of the video signal frame. This is relatively unobtrusive, but being in-vision is copied through all the usual editing processes. As an alternative the code could be at the bottom of the frame, as indicated at 50a for the previous frame on Fig. 4. The code is introduced into the videotape recorder output at step 52 in Fig. 2.

The code is akin to a bar code, and we find it convenient to use a code based on the EBU standard VITC code, discussed above in relation to the final edited videotape. To ensure that it fits within the active picture area, even after the tolerances of the editing operation, the code is slightly compressed by e.g. about 10% into a shorter part of the line length. It is repeated on several lines, preferably six, so that even after a degree of skewing has been introduced in editing there will still be at least one readable line.

The EBU standard code has provision for several "user bits" in addition to the normal frame count or its equivalent. These user bits can be used to hold the spool number, so that the full code identifies uniquely the frame concerned on a specified spool.

After the 16mm film has been edited, it is transferred back to VT ready for the final conforming process. The originating VT reel and time code information for each edited section remains at the top of frame for decoding by a VITC reader modified slightly as described below, ready for automatic feeding to the conforming edit system.

This data can be entered directly into a computer programme developed for the conforming of videotape off-line edited material.

At the same time, by noting relevant changes in the code, the intermediate or final master longitudinal or vertical time code is stored, giving the ability of direct automatic data entry into the conforming control system. None of the time consuming preparation and data retrieval of existing systems is necessary.

Thus in Fig. 2 a modified VITC reader 54 is included which reads the in-vision code either as shown as the work print is being run through a telecine or directly from the resultant videotape. The added code can be picked out from the video signal by using a standard VITC code reader, modified to look for the code in the first few lines of the active picture signal instead of in the vertical frame blanking interval, and to take account of the slightly compressed format of the code. Suitable VITC generators and readers are available from for example Avitel Limited of Beckenham, Kent, as their TGE 2040 VITC generator and TRE 2060 reader.Some relaxation of the tolerances of the code detection circuitry may be necessary as, during the film processes, the invision codes may have suffered some distortion, particularly where edits take place.

It will be appreciated that we now have available a signal in electrical form representative of the sequence of frame numbers from the original material which have been retained in the edited work print. This sequence of frame numbers can now be processed by comparing each frame number with the frame number for the preceding frame. Most of the time the frame numbers will increment steadily, but whever an edit point is reached there will be a discontinuity in the frame number sequence. This can be detected in the change detector 56, and the frame numbers immediately to either side of the edit point automatically logged at 58.

This now gives a sequential listing of the first and last frames of each slot which is used in the work print. The enormous task of manually listing these frame numbers has been completely avoided. The sequence of frame numbers is sufficient to enable the final conforming operation to take place by working through the shots in turn. In practice, it is much easier if all the shots from each master spool can be conformed at a time, and it is therefore much preferred when forming the data log to correlate the edited in-vision code with the final VITC code generated by time code generator 34.

The edited in-vision codes are then monitored as just described to detect edit points and for each edit point the log includes the following data: (i) Serial number of the edit (ii) Spool number of the frame preceding the edit (iii) Edited in-vision code for the frame preceding the edit (iv) Final VITRO code for the frame preceding the edit (v) Spool number of the frame following the edit (vi) Edited in-vision code for the frame following the edit (vii) Final VITC code for the frame following the edit.

This data can conveniently be stored and processed in a disc-based microcomputer. It will be appreciated that the data could be stored on a "shot" basis rather than an "edit" basis, and the two systems are equivalent in practice.

The listing can be rearranged in any desired manner. For example, all shots from any given original master spool can be grouped together.

The spools are then conformed in turn. For each spool the first shot used is identified and the VT machine 12 run to the start of the shot as identified by the in-vision code. The conforming machine 20 is run to the corresponding position as indicated by the final VITC code. Conforming of that shot then takes place. The operator then moves to the next shot from that master spool.

Even if the data log still has to be entered manually into the edit control system, substantial savings in the tedious work involved in producing the log are obtained. However, greater advantages are obtained if the log is directly entered into the edit control system.

The edit control may still be initiated manually, with the operator taking each shot in turn.

The system, however would enable further automation of the conforming operation in which all the operator had to do was to put the master spools on the videotape machine 12 in the order instructed by the edit control system.

The even-odd PAL sequence can be monitored automatically and the necessary adjustment made in the edit control system to ensure that the alternation is maintained in the final output. Various known methods exist for making the necessary correction in the event that two even or two odd frames are due to appear successively, the simplest being simply to omit one frame altogether.

Thus the use of the in-vision digital code such as the modified VITC code described with the 'user bits' being used to hold the spool or reel members enables further development of the system to an extremely efficient conforming process. The in-vision digital coding, can be used for the purposes of conforming, or for editing or synchronisation of sound or vision.

Reference should also be made to British Patent No. 2,172,119A from which this patent is divided.

Claims (4)

1. Apparatus for generating a lifting of edits in a cinematographic film, the film being provided with a unique machine-readable frame identification associated with successive frames of the film, the apparatus comprising reading means for reading the frame identifications from the film or from videotape derived thereform, comparison means for comparing the frame identifications of successive frames to detect discontinuities in the sequence of frame identifications to identify an edit point, and storage means for storing the frame identications of the frames to either side of the edit point.

2. Apparatus according to claim 1, further comprising means for storing VITC codes in association with each of the said stored frame identifications.

3. Apparatus according to claim 1 or 2, further comprising means for automatically entering the stored data into a conforming edit control system.

4. Editing apparatus substantially as herein described with reference to Fig. 2 of the drawings.