diff options
| author | Paul B Mahol <onemda@gmail.com> | 2020-12-02 14:28:01 +0300 |
|---|---|---|
| committer | Paul B Mahol <onemda@gmail.com> | 2020-12-02 14:30:10 +0300 |
| commit | 0a5ff1964355f6d288071b7c0bc4fb24f658c9fc (patch) | |
| tree | 2cedd81a6f516e85945b62f7c4311ad0910baaaa | |
| parent | ba6e2a2d05826941ea66920ba25a76db32bd0a73 (diff) | |
avfilter/af_acrossover: document roll-off of each filter order
| -rw-r--r-- | doc/filters.texi | 14 | ||||
| -rw-r--r-- | libavfilter/af_acrossover.c | 22 |
2 files changed, 24 insertions, 12 deletions
diff --git a/doc/filters.texi b/doc/filters.texi index d2afc7115d..f7b8f92629 100644 --- a/doc/filters.texi +++ b/doc/filters.texi @@ -523,19 +523,31 @@ The filter accepts the following options: Set split frequencies. Those must be positive and increasing. @item order -Set filter order. Available values are: +Set filter order for each band split. This controls filter roll-off or steepness +of filter transfer function. +Available values are: @table @samp @item 2nd +12 dB per octave. @item 4th +24 dB per octave. @item 6th +36 dB per octave. @item 8th +48 dB per octave. @item 10th +60 dB per octave. @item 12th +72 dB per octave. @item 14th +84 dB per octave. @item 16th +96 dB per octave. @item 18th +108 dB per octave. @item 20th +120 dB per octave. @end table Default is @var{4th}. diff --git a/libavfilter/af_acrossover.c b/libavfilter/af_acrossover.c index 0be2f3a76f..241f1dbb77 100644 --- a/libavfilter/af_acrossover.c +++ b/libavfilter/af_acrossover.c @@ -83,17 +83,17 @@ typedef struct AudioCrossoverContext { static const AVOption acrossover_options[] = { { "split", "set split frequencies", OFFSET(splits_str), AV_OPT_TYPE_STRING, {.str="500"}, 0, 0, AF }, - { "order", "set order", OFFSET(order_opt), AV_OPT_TYPE_INT, {.i64=1}, 0, 9, AF, "m" }, - { "2nd", "2nd order", 0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, AF, "m" }, - { "4th", "4th order", 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, AF, "m" }, - { "6th", "6th order", 0, AV_OPT_TYPE_CONST, {.i64=2}, 0, 0, AF, "m" }, - { "8th", "8th order", 0, AV_OPT_TYPE_CONST, {.i64=3}, 0, 0, AF, "m" }, - { "10th", "10th order", 0, AV_OPT_TYPE_CONST, {.i64=4}, 0, 0, AF, "m" }, - { "12th", "12th order", 0, AV_OPT_TYPE_CONST, {.i64=5}, 0, 0, AF, "m" }, - { "14th", "14th order", 0, AV_OPT_TYPE_CONST, {.i64=6}, 0, 0, AF, "m" }, - { "16th", "16th order", 0, AV_OPT_TYPE_CONST, {.i64=7}, 0, 0, AF, "m" }, - { "18th", "18th order", 0, AV_OPT_TYPE_CONST, {.i64=8}, 0, 0, AF, "m" }, - { "20th", "20th order", 0, AV_OPT_TYPE_CONST, {.i64=9}, 0, 0, AF, "m" }, + { "order", "set filter order", OFFSET(order_opt), AV_OPT_TYPE_INT, {.i64=1}, 0, 9, AF, "m" }, + { "2nd", "2nd order (12 dB/8ve)", 0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, AF, "m" }, + { "4th", "4th order (24 dB/8ve)", 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, AF, "m" }, + { "6th", "6th order (36 dB/8ve)", 0, AV_OPT_TYPE_CONST, {.i64=2}, 0, 0, AF, "m" }, + { "8th", "8th order (48 dB/8ve)", 0, AV_OPT_TYPE_CONST, {.i64=3}, 0, 0, AF, "m" }, + { "10th", "10th order (60 dB/8ve)",0, AV_OPT_TYPE_CONST, {.i64=4}, 0, 0, AF, "m" }, + { "12th", "12th order (72 dB/8ve)",0, AV_OPT_TYPE_CONST, {.i64=5}, 0, 0, AF, "m" }, + { "14th", "14th order (84 dB/8ve)",0, AV_OPT_TYPE_CONST, {.i64=6}, 0, 0, AF, "m" }, + { "16th", "16th order (96 dB/8ve)",0, AV_OPT_TYPE_CONST, {.i64=7}, 0, 0, AF, "m" }, + { "18th", "18th order (108 dB/8ve)",0, AV_OPT_TYPE_CONST, {.i64=8}, 0, 0, AF, "m" }, + { "20th", "20th order (120 dB/8ve)",0, AV_OPT_TYPE_CONST, {.i64=9}, 0, 0, AF, "m" }, { "level", "set input gain", OFFSET(level_in), AV_OPT_TYPE_FLOAT, {.dbl=1}, 0, 1, AF }, { NULL } }; |