WriteFile - Revision history

Reel.Deal: add link to avs+ documentation

2022-09-18T04:47:24Z

add link to avs+ documentation

Raffriff42: formatting, links, phrasing

2016-02-28T11:01:27Z

formatting, links, phrasing

Raffriff42: added category

2015-11-08T15:47:16Z

added category

Raffriff42: formatting (bold, bullets); clarify 'append', 'flush'

2015-09-11T04:27:37Z

formatting (bold, bullets); clarify 'append', 'flush'

Admin: 1 revision

2013-05-09T15:02:26Z

1 revision

Wilbert: nearly unlimited number of expressions

2010-01-05T19:05:34Z

nearly unlimited number of expressions

New page

{{Template:Func4Def|WriteFile(clip ''clip'', string ''filename'', string ''expression1'' [, string ''expression2'' [, ...]] [, bool ''append'', bool ''flush''])|WriteFileIf(clip ''clip'', string ''filename'', string ''expression1'' [, string ''expression2'' [, ...]] [, bool ''append'', bool ''flush''])|WriteFileStart(clip ''clip'', string ''filename'', string ''expression1'' [, string ''expression2'' [, ...]] [, bool ''append''])|WriteFileEnd(clip ''clip'', string ''filename'', string ''expression1'' [, string ''expression2'' [, ...]] [, bool ''append''])}}

WriteFile evaluates each ''expressionN'', converts the result to a string and puts the concatenated results into a file, followed by a newline.

The "run-time" variable current_frame is set so that you can use it in an ''expression'' (this works similar as with [[ScriptClip]], look there in the docs for more info). current_frame is set to -1 when the script is loaded and to -2 when the script is closed.

WriteFile evaluates the ''expression''s and generates output for each frame rendered by the filter. WriteFileIf is similar, but generates output only if the first expression is true. In both cases, there is no output at script opening or closure. Note that since output is produced only for ''rendered'' frames, there will be no output at all if the result of the filter is not used in deriving the final result of the script.

WriteFileStart and WriteFileEnd generate output only on script opening and closure respectively, there is no action on each frame. In both cases, the ''expression''s are evaluated exactly once, at the location of the filter in the script.

When ''append = true'', the result(s) will be appended to any existing file. The default for ''append'' is always ''true'', except for WriteFileStart (here it is ''false'').

When ''flush = true'', the file is closed and reopened after each operation so you can see the result immediately (this may be slower). The default for ''flush'' (WriteFile and WriteFileIf) is ''true''. For WriteFileStart and WriteFileEnd, the file is always closed immediately after writing.

Usage is best explained with some simple examples:

filename = "c:\myprojects\output.txt"
# create a test video to get frames
Version()

# the expression here is only a variable, which is evaluated and put in the file
# you will get a file with the framenumber in each line
WriteFile(filename, "current_frame")

# this line is written when the script is opened
WriteFileStart(filename, """ "This is the header" """)

# and this when the script is closed
WriteFileEnd(filename, """ "Now the script was closed" """)

Look how you can use triple-quotes to type a string in a string! If the expression cannot be evaluated, the error message is written instead. In case this happens with the If-expression in WriteFileIf the result is assumed to be true.

# will result in "I don't know what "this" means"
WriteFile(filename, "this is nonsense")

There are easier ways to write numbers in a file, BUT with this example you can see how to use the "runtime function" AverageLuma:

# create a test video to get different frames
Version.FadeIn(50).ConvertToYV12()

# this will print the frame number, a ":" and the average luma for that frame
colon = ": "
WriteFile("F:\text.log", "current_frame", "colon", "AverageLuma")

Or maybe you want the actual time printed, too:

# create a test video to get different frames
Version.FadeIn(50).ConvertToYV12()

# this will print the frame number, the current time and the average luma for that frame
# the triple quotes are necessary to put quotes inside a string
WriteFile(last, filename, "current_frame", """ time(" %H:%M:%S") """, "AverageLuma")

'''More examples:'''

In WriteFileIf the FIRST expression is expected to be boolean (true or false).
Only if it is TRUE the other expressions are evaluated and the line is printed.
(Remember: && is AND, || is OR, == is EQUAL, != is NOT EQUAL)
That way you can omit lines completely from your file.

# create a test video to get different frames
Version.FadeIn(50).ConvertToYV12()

# this will print the frame number, but only of frames where AverageLuma is between 30 and 60
WriteFileIf(last, filename, "(AverageLuma>30) && (AverageLuma<60)", "current_frame", """ ":" """, "AverageLuma")

'''Changes:'''
{| border="1"
|-
| v2.60
| Number of expressions changed from 16 to nearly unlimited.
|-
| v2.55
| Initial release.
|}

[[Category:Internal filters]]

@@ Line 1: / Line 1: @@
 <div style="max-width:62em" >
 {{Func4Def
 |WriteFile(clip ''clip'', string ''filename'', string ''expression1'' [, string ''expression2'' [, ...]] [, bool ''append'', bool ''flush''])

@@ Line 1: / Line 1: @@
-{{Template:Func4Def|WriteFile(clip ''clip'', string ''filename'', string ''expression1'' [, string ''expression2'' [, ...]] [, bool ''append'', bool ''flush''])|WriteFileIf(clip ''clip'', string ''filename'', string ''expression1'' [, string ''expression2'' [, ...]] [, bool ''append'', bool ''flush''])|WriteFileStart(clip ''clip'', string ''filename'', string ''expression1'' [, string ''expression2'' [, ...]] [, bool ''append''])|WriteFileEnd(clip ''clip'', string ''filename'', string ''expression1'' [, string ''expression2'' [, ...]] [, bool ''append''])}}
+<div style="max-width:62em" >
 '''WriteFile''' and related functions evaluate each [[Grammar|''expression'']], convert the result to a string and put the concatenated results into a file, followed by a newline.
-*'''WriteFile''' evaluates the ''expression''s and generates output for each frame rendered by the filter.
+*'''WriteFile''' evaluates the {{FuncArg|expression}}s and generates output for each frame rendered by the filter.
-*'''WriteFileIf''' is similar, but generates output only if the first expression is ''true''.
+*'''WriteFileIf''' is similar, but generates output only if the first expression evaluates to  ''true''.
 :* In both cases, there is no output at script opening or closure.
 :* Note that with [[ScriptClip]], script opening and closure occurs on every frame.
@@ Line 13: / Line 19: @@
 :* The ''expression''s are evaluated exactly once, at the location of the filter in the script.
-*When ''append = true'', the results will be appended to any existing file ''filename''; if ''false'', a new file is created and the old one is overwritten.
+*When {{FuncArg|append}}=''true'', the results will be appended to any existing file {{FuncArg|filename}}; if ''false'', a new file is created and the old one is overwritten.
 :* Only script opening and closure are affected; '''WriteFile''' and '''WriteFileIf''' per-frame execution ''always'' append.
-:* The default for ''append'' is ''true'', except for '''WriteFileStart''', where it is ''false''.
+:* The default for {{FuncArg|append}} is ''true'', except for '''WriteFileStart''', where it is ''false''.
-*When ''flush = true'', after each operation a 'flush' is performed: any unwritten data is written to disk, and the file is closed and reopened.
+*When {{FuncArg|flush}}=''true'', after each operation a ''flush'' is performed: any unwritten data is written to disk, and the file is closed and reopened.
 :* After flushing you may read the updated file immediately, either through [[ConditionalReader]] or an external application.
-:* The default for ''flush'' is ''true'' for '''WriteFile''' and '''WriteFileIf''' and ''always'' true (no user option) for '''WriteFileStart''' and '''WriteFileEnd'''.
+:* The default for {{FuncArg|flush}} is ''true'' for '''WriteFile''' and '''WriteFileIf''' and ''always'' true (no user option) for '''WriteFileStart''' and '''WriteFileEnd'''.
 :* Note that flushing after every frame may be significantly slower.
-*The [[Runtime_environment#Special_runtime_variables_and_functions|run-time variable]] ''current_frame'' is set so that you can use it in ''expression''s (as with [[ScriptClip#ScriptClip|ScriptClip]]).
+*The [[Runtime_environment#Special_runtime_variables_and_functions|run-time variable]] ''current_frame'' is set so that you can use it in {{FuncArg|expression}}s (as with [[ScriptClip#ScriptClip|ScriptClip]]).
 :* ''current_frame'' is set to ''-1'' when the script is loaded and to ''-2'' when the script is closed.
-<hr>
+----
 Usage is best explained with some simple examples:
+<div {{BoxWidthIndent|58|0}} >
   filename = "c:\myprojects\output.txt"
   # create a test video to get frames
@@ Line 42: / Line 50: @@
   # and this when the script is closed
   WriteFileEnd(filename, """ "Now the script was closed" """)
-Look how you can use triple-quotes to type a string in a string! If the expression cannot be evaluated, the error message is written instead. In case this happens with the If-expression in WriteFileIf the result is assumed to be true.
+Look how you can use triple-quotes to type a string inside a string! If the expression cannot be evaluated, the error message is written instead. In case this happens with the If-expression in '''WriteFileIf''', the result is assumed to be true.
+<div {{BoxWidthIndent|58|0}} >
   # will result in "I don't know what "this" means"
   WriteFile(filename, "this is nonsense")
-There are easier ways to write numbers in a file, BUT with this example you can see how to use the "runtime function" AverageLuma:
+There are easier ways to write numbers in a file, BUT with this example you can see how to use the ''runtime function'' [[AverageLuma]]:
+<div {{BoxWidthIndent|58|0}} >
   # create a test video to get different frames
   Version.FadeIn(50).ConvertToYV12()
@@ Line 56: / Line 66: @@
   colon = ": "
   WriteFile("F:\text.log", "current_frame", "colon", "AverageLuma")
 Or maybe you want the actual time printed, too:
+<div {{BoxWidthIndent|58|0}} >
   # create a test video to get different frames
   Version.FadeIn(50).ConvertToYV12()
@@ Line 65: / Line 76: @@
   # the triple quotes are necessary to put quotes inside a string
   WriteFile(last, filename, "current_frame", """ time(" %H:%M:%S") """, "AverageLuma")
 '''More examples:'''
-In WriteFileIf the FIRST expression is expected to be boolean (true or false).
+In '''WriteFileIf''' the FIRST expression is expected to be boolean (true or false).
 Only if it is TRUE the other expressions are evaluated and the line is printed.
 (Remember: && is AND, || is OR, == is EQUAL, != is NOT EQUAL)
 That way you can omit lines completely from your file.
+<div {{BoxWidthIndent|58|0}} >
   # create a test video to get different frames
   Version.FadeIn(50).ConvertToYV12()
-  # this will print the frame number, but only of frames where AverageLuma is between 30 and 60
+  # this will print the frame number,
-  WriteFileIf(last, filename, "(AverageLuma>30) && (AverageLuma<60)", "current_frame", """ ":" """, "AverageLuma")
+ # but only of frames where AverageLuma is between 30 and 60
 '''Changes:'''
@@ Line 88: / Line 103: @@
 | Initial release.
 |}
+</div>
 [[Category:Internal filters]]
 [[Category:Meta_filters]]
 [[Category:Runtime_filters]]

← Older revision		Revision as of 15:47, 8 November 2015
Line 91:		Line 91:

	[[Category:Internal filters]]		[[Category:Internal filters]]
		+	[[Category:Meta_filters]]
		+	[[Category:Runtime_filters]]

@@ Line 1: / Line 1: @@
 {{Template:Func4Def|WriteFile(clip ''clip'', string ''filename'', string ''expression1'' [, string ''expression2'' [, ...]] [, bool ''append'', bool ''flush''])|WriteFileIf(clip ''clip'', string ''filename'', string ''expression1'' [, string ''expression2'' [, ...]] [, bool ''append'', bool ''flush''])|WriteFileStart(clip ''clip'', string ''filename'', string ''expression1'' [, string ''expression2'' [, ...]] [, bool ''append''])|WriteFileEnd(clip ''clip'', string ''filename'', string ''expression1'' [, string ''expression2'' [, ...]] [, bool ''append''])}}
-WriteFile evaluates each ''expressionN'', converts the result to a string and puts the concatenated results into a file, followed by a newline.
+'''WriteFile''' and related functions evaluate each [[Grammar|''expression'']], convert the result to a string and put the concatenated results into a file, followed by a newline.
-The "run-time" variable current_frame is set so that you can use it in an ''expression'' (this works similar as with [[ScriptClip]], look there in the docs for more info). current_frame is set to -1 when the script is loaded and to -2 when the script is closed.
+*'''WriteFile''' evaluates the ''expression''s and generates output for each frame rendered by the filter.
-WriteFile evaluates the ''expression''s and generates output for each frame rendered by the filter. WriteFileIf is similar, but generates output only if the first expression is true. In both cases, there is no output at script opening or closure. Note that since output is produced only for ''rendered'' frames, there will be no output at all if the result of the filter is not used in deriving the final result of the script.
+*'''WriteFileStart''' and '''WriteFileEnd''' generate output only on script opening and closure respectively.
-WriteFileStart and WriteFileEnd generate output only on script opening and closure respectively, there is no action on each frame. In both cases, the ''expression''s are evaluated exactly once, at the location of the filter in the script.
+*When ''append = true'', the results will be appended to any existing file ''filename''; if ''false'', a new file is created and the old one is overwritten.
-When ''append = true'', the result(s) will be appended to any existing file. The default for ''append'' is always ''true'', except for WriteFileStart (here it is ''false'').
+*When ''flush = true'', after each operation a 'flush' is performed: any unwritten data is written to disk, and the file is closed and reopened.
-When ''flush = true'', the file is closed and reopened after each operation so you can see the result immediately (this may be slower). The default for ''flush'' (WriteFile and WriteFileIf) is ''true''. For WriteFileStart and WriteFileEnd, the file is always closed immediately after writing.
+*The [[Runtime_environment#Special_runtime_variables_and_functions|run-time variable]] ''current_frame'' is set so that you can use it in ''expression''s (as with [[ScriptClip#ScriptClip|ScriptClip]]).
+:* ''current_frame'' is set to ''-1'' when the script is loaded and to ''-2'' when the script is closed.
 Usage is best explained with some simple examples:
@@ Line 20: / Line 34: @@
   # the expression here is only a variable, which is evaluated and put in the file
-  # you will get a file with the framenumber in each line
+  # you will get a file with the frame number in each line
   WriteFile(filename, "current_frame")