Record Short Movie - Fast Single Pass

Record Short Movie - Fast Single Pass

This option provides an alternative mechanism for recording short movies at a higher frame rate than [;KMR Record movie - single pass] while maintaining a single pass. It records with either manual or computer controlled synchronisation in a single pass. If the requested frame rate exceeds that the computer is capable of, then frames will be dropped and the maximum achievable rate will be used.

The higher frame rate is achieved by caching the movie into the extended memory normally occupied by the extended memory buffers.

DigImage movie files normally have a .MOV extension and consist of a sequence of images stored in a single file. They are accessed as a direct access binary file with one byte per record. The file format consists of four blocks of header information followed by the raw image data:

GeneralHeader 256 bytes 

                   Contains general information

HistoryHeader 256 bytes 

                   Contains information about the file history

MovieHeader 1024 bytes 

                   Contains information about the images and movie sequence

MovieFrameTable 32768 bytes 

                   Stores pointers to each frame (maximum of 2048) in the
                   movie

For complete details on each of these headers, refer to DigImage\Include\Headers.INC.

Name of movie to be created (.MOV default extension) ?

The images acquired as part of the movie will be stored in the file specified here. For full details of the format of this file, refer to DigImage\Include\Headers.INC.

Set recording window using which buffer ?

Only the region of the image falling within a user specified window will be recorded. The smaller this window is, the closer the samples may be together without loosing data. The buffer specified here will be displayed while the window is being specified.

Window Selection: Region to record in movie

The Window Selection submenu is produced to allow the desired region to be selected. For further information on the use of windows, refer the [H Help] within the Window Selection submenu.

Horizontal step ?

By sampling the image on a coarser grid the frame rate of the recording may be increased. This entry specifies the horizontal spacing between samples to be included in the movie image.

THIS ENTRY IS IGNORED. THE STEP SIZE IS ALWAYS SET TO UNITY

Vertical step ?

This entry specifies the vertical spacing between the samples to be included in the movie image.

THIS ENTRY IS IGNORED. THE STEP SIZE IS ALWAYS SET TO UNITY

Spacing between images ?

This entry specifies the temporal sampling frequency or frame rate of the movie. If the requested frequency is too high (spacing too small), then it will not be possible to maintain the required interval between images.

Duration of movie ?

The duration of the movie is fixed by this entry. The duration is converted into the number of samples to be recorded. The duration of the movie will be adhered to (as closely as possible) even if DigImage is not able to maintain the requested frame rate.

DigImage requires exclusive use of all the extended memory buffers for this operation. Do you wish to save their contents first? (requires !!GR2MBytes and takes approx !!R3s)

DigImage uses the memory occupied by the extended memory buffers to cache the movie information, thus destroying the original contents of the buffers. As an option, the contents may be saved prior to recording the movie and subsequently restored. This procedure

Manual or Computer synchronisation ?

The start point of the movie may be provided by either manual (<M>) synchronisation with the video, or by direct computer control (<C>).

{If computer synchronisation}

Start time (offset from current position) ?

The movie recording will start at the specified offset from the current position of the VTR. If positive the movie will start after this point, while negative will make the movie start before this point.

{If computer synchronisation}

On completion Reposition video tape or Leave it where it is ?

Once the acquisition has been completed, the video tape may be either repositioned to its initial location (<R>), or simply left where it is. In both cases the location may be obtained through the !!V system variable.

{If manual synchronisation}

Start recording or Quit ?

This message will be produced when DigImage is ready to start recording the movie if manual synchronisation is being used.

Errors, Warnings and Messages

Insufficient memory for this many frames. Will only record for !!R0 samples

DigImage can only record as many frames as there is available space in extended memory.

Recording !!R0 samples into extended memory...

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Stuart Dalziel, last page update: 19 February 1996