compress: Document and sanity-check command line options.

[paraslash.git] / m4 / lls / filter_cmd.suite.m4

diff --git a/m4/lls/filter_cmd.suite.m4 b/m4/lls/filter_cmd.suite.m4
index ddc5f1cb3c191df7d472732f76af40645f02ccf6..1399de62e8e38cfb955e9b16a8788aa6cd684c75 100644 (file)
--- a/m4/lls/filter_cmd.suite.m4
+++ b/m4/lls/filter_cmd.suite.m4
@@ -25,7 +25,7 @@ caption = filters
        purpose = dynamically adjust the volume of an audio stream
        [option blocksize]
                short_opt = b
-               summary = use blocks of size 2**bits
+               summary = adjust volume after each block of size 2**bits (1-31)
                typestr = bits
                arg_info = required_arg
                arg_type = uint32
@@ -35,18 +35,26 @@ caption = filters
                [/help]
        [option aggressiveness]
                short_opt = a
-               summary = controls the maximum amount to amplify by
+               summary = controls the maximum amount to amplify by (1-15)
                typestr = bits
                arg_info = required_arg
                arg_type = uint32
                default_val = 4
+               [help]
+                       This caps the maximal gain factor to 2**bits. The sum of the arguments
+                       to --aggressiveness and --inertia (see below) must not exceed 16.
+               [/help]
        [option inertia]
                short_opt = i
-               summary = how much inertia ramping has
+               summary = how much inertia ramping has (1-15)
                typestr = bits
                arg_info = required_arg
                arg_type = uint32
                default_val = 6
+               [help]
+                       Larger values cause smaller volume adjustments. See --aggressiveness
+                       above.
+               [/help]
        [option target-level]
                short_opt = t
                summary = target signal level (0-32767)
@@ -54,13 +62,25 @@ caption = filters
                arg_info = required_arg
                arg_type = uint32
                default_val = 20000
+               [help]
+                       If the peak of the previous block is less than the target level,
+                       volume is increased slightly for the next block. Otherwise it is
+                       decreased. The default value is chosen to minimize clipping. There
+                       is usually no reason to change it.
+               [/help]
        [option damp]
                short_opt = d
-               summary = if non-zero, scale down after normalizing
+               summary = if non-zero, scale down after normalizing (0-16)
                typestr = bits
                arg_info = required_arg
                arg_type = uint32
                default_val = 0
+               [help]
+                       This scales down the volume of the audio stream by factor 2**bits.
+                       This is mostly useful if another audio application (e.g., a video
+                       game) is running in parallel and the relative volume of the audio
+                       stream is too high.
+               [/help]
 [subcommand fecdec]
        purpose = decode a (lossy) input stream using forward error correction
 [subcommand flacdec]