Delta file (difference file)
Compare two video files by using a delta file (difference file).
-i input_file_1 \
-i input_file_2 \
-map "[out]" \
- starts the command
- path, name and extension of the first input files
- path, name and extension of the second input files
- A complex filter graph is needed:
- three filters are applied successively to the second input file (this is a filter chain):
- an alpha channel is added,
- the alpha channel is set to “medium grey” and
- the colours are inverted;
- the overlay between the first input file and the colour-inverted second input file gives the difference.
- maps the [out] stream to the output
- path, name and extension of the output file
A delta file is useful for comparing files with little differences, while for comparing files with big differences a split screen may be a better choice.
The different filters of a filter chain are divided by a comma (
,). The different filter chains of a filter graph are divided by a semi-colon (
;). If the whole filter graph is put into quotation marks, then spaces can be added after
; for readability reasons.
The mapping is not necessary in this case, because it’s implicit.
- alpha channel set to another colour than “medium grey”
- delta file of input files with 10-bit per colour channel