AviSynth Syntax - Debug helper function

Filter graph handling and logging.

Filter graph

Switch it on by putting SetGraphAnalysis(true) at the beginning of the script. Dump to text file with DumpFilterGraph. E.g. DumpFilterGraph("graph.txt", mode=2) Output is in "dot" format, it can be converted to an image with Graphviz as follows:

dot -Tsvg graph.txt -o graph.svg

SetGraphAnalysis

SetGraphAnalysis (bool)

Enables (true) or disables (false) graph node insertion into the instantiated filter. To output a filter graph, a graph node must be inserted in the filter. When a graph node is inserted, performance may decrease slightly due to the increase of internal function calls. (In most cases, there is no observable performance degradation.)

DumpFilterGraph

DumpFilterGraph (clip, string "outfile", int "mode", int "nframes", bool "repeat")

Outputs a filter graph.

clip

Clip to output filter graph

string outfile = ""

Output file path

int mode = 0

int nframes = -1

Outputs the filter graph when processing the specified frame. The cache size and memory usage of each filter at that time are output together. This is effective when you want to know the memory usage of each filter. If -1, output when DumpFilterGraph is called (before the frame is processed).

bool repeat = false

Valid only when nframes> 0. Outputs a filter graph repeatedly at nframes intervals.

Logging

SetLogParams

SetLogParams([string target, int level])

Sets a file path for a log file, used by LogMsg and internal error reporting.

string target

Names a file which will be created when the script loads. If attempting to create or write to target fails, the script will raise an error immediately. If the file exists, new log entries will be appended to the end. If omitted, target defaults to stderr.

int level

Sets the log verbosity; it can be one of the following:

• LOG_ERROR (1) creates the fewest log entries

• LOG_WARNING (2)

• LOG_INFO (3) creates the most log entries

If omitted, level defaults to LOG_INFO.

For examples see LogMsg below.

LogMsg

LogMsg(string, int)

Creates a new log entry.

string (required)

specifies the log message.

int (required)

specifies the log entry level: see SetLogParams above.

Examples:

## creating file and set path for future log entries:
SetLogParams("<path>\_test1.log", LOG_INFO)

log content at this point:

(empty)

## logging an INFO message:
SetLogParams("<path>\_test2.log", LOG_INFO)
LogMsg("this is a test", LOG_INFO)

log contents at this point:

---------------------------------------------------------------------
INFO: this is a test

## logging a script error:
SetLogParams("<path>\_test3.log", LOG_INFO)
foo("bar") ## ERROR!

log contents (redundant entries are common):

ERROR: Script error: There is no function named 'foo'.
---------------------------------------------------------------------
ERROR: Script error: There is no function named 'foo'.
(<path>\_test.avs, line 35)

## logging INFO context for script error:
SetLogParams("<path>\_test4.log", LOG_INFO)
function MyFunction(clip C)
{
    C
    try {
        foo("bar") ## ERROR!
    } catch (err_msg) {
        msg2 = "Error in MyFunction: "
        LogMsg(Time("%Y-%m-%d %I:%M:%S %p, %z") + ": " + msg2, LOG_INFO)
        #Assert(false, msg2 + err_msg) ## optional: stop script, else continue
    }
    return Last
}

log contents (redundant entries omitted):

---------------------------------------------------------------------
ERROR: Script error: There is no function named 'foo'.
(<path>\_test.avs, line 54)
---------------------------------------------------------------------
INFO: 2017-11-12 11:03:41 AM, -0500: Error in MyFunction:
(<path>\_test.avs, line 54)

Changelog

Version	Changes
AviSynth 3.7.4	Fix SetLogParams defaults
AviSynth+	all of them

Back to Internal functions.

$Date: 2024/04/10 9:43:00 $