sspmod_varfr.c File Reference

Variable frame rate analysis. More...

Functions
int	spr_varfr_setup (SprSspInfo *Info, const char **descript, void *aux_info)
int	spr_varfr_process (SprSspInfo *Info, const void *frame_in, void *frame_out)
void	spr_varfr_reset (SprSspInfo *Info, SprSspStatus *action)
void	spr_varfr_free (SprSspInfo *Info)

Detailed Description

Variable frame rate analysis.

Frames are left out according to distance (between two vectors) or norm (of the vector) criteria. If it is above a given threshold, the frame is left out, except if the number of successive frames left out before exceeds a given limit. Normally the routine gives no return, only states that a frame should be skipped or not. The possibility exists to return the number of frames that a not-skipped frame represents: if e.g. 5 frames were left out before that frame, then the integer '6' is given. The first frame of a file is always retained. There is no special arrangement for the last frames (so it's very well possible that e.g. the last 3 frames are simply left out). It is possible to write the new number of frames to MsgStream (for bookkeeping purposes). Note: the history in this routine is set to 0, which means that other frames can be selected if only a part of the datafile is processed.

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[varfr]
threshold <number>
Decision threshold for variable frame rate, default 0.0.
limit <number>
Max nr of successive frames to be left out, default 50.
reference <norm_of_frame/prev_frame/last_retained_frame>
Criterion: norm of the input (normally of derivative), distance to the previous frame, or distance to the last retained frame. Default last_retained_frame.
duration <yes/no>
Return duration of each retained frame, default no. Note that default no output is given at all, 'COPY' and 'PROCESS' should be used.
new_nfr <yes/no>
Write the new nr of frames in text format to MsgStream, default no.

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See Also

ssp_master.c

Author

Philippe Le Cerf (algorithm), Jacques Duchateau (ssp routines)

Date

7 Nov 1991 and 13 Dec 1994