avfilter: Deduplicate default audio inputs/outputs

Lots of audio filters use very simple inputs or outputs:
An array with a single AVFilterPad whose name is "default"
and whose type is AVMEDIA_TYPE_AUDIO; everything else is unset.

Given that we never use pointer equality for inputs or outputs*,
we can simply use a single AVFilterPad instead of dozens; this
even saves .data.rel.ro (4784B here) as well as relocations.

*: In fact, several filters (like the filters in af_biquads.c)
already use the same inputs; furthermore, ff_filter_alloc()
duplicates the input and output pads so that we do not even
work with the pads directly.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/libavfilter/audio.c b/libavfilter/audio.c
index 36d5caa7e4..35270c14d2 100644
--- a/libavfilter/audio.c
+++ b/libavfilter/audio.c
@@ -29,6 +29,13 @@
 #include "framepool.h"
 #include "internal.h"
 
+const AVFilterPad ff_audio_default_filterpad[1] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_AUDIO,
+    }
+};
+
 AVFrame *ff_null_get_audio_buffer(AVFilterLink *link, int nb_samples)
 {
     return ff_get_audio_buffer(link->dst->outputs[0], nb_samples);