Record Movie
Record Movie
This option provides the main mechanism for recording movies. 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 option [U Record movie using mask - single pass] offers the same
features plus the ability to perform ALU operations during acquisition.
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.
Vertical step ?
This entry specifies the vertical spacing between the samples to be
included in the movie image.
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. If
the spacing is not a multiple of the spacing between images for the video
source (1/25 or 1/30s for PAL or NTSC), then the sample spacing used will
not be constant but will be chosen so as to best approximate the requested
spacing.
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.
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.
Parent menu
Main Menu
DigImage User Documentation
Stuart Dalziel,
last page update: 19 February 1996