avfilter/avfilter: Add numbers of (in|out)pads directly to AVFilter

Up until now, an AVFilter's lists of input and output AVFilterPads
were terminated by a sentinel and the only way to get the length
of these lists was by using avfilter_pad_count(). This has two
drawbacks: first, sizeof(AVFilterPad) is not negligible
(i.e. 64B on 64bit systems); second, getting the size involves
a function call instead of just reading the data.

This commit therefore changes this. The sentinels are removed and new
private fields nb_inputs and nb_outputs are added to AVFilter that
contain the number of elements of the respective AVFilterPad array.

Given that AVFilter.(in|out)puts are the only arrays of zero-terminated
AVFilterPads an API user has access to (AVFilterContext.(in|out)put_pads
are not zero-terminated and they already have a size field) the argument
to avfilter_pad_count() is always one of these lists, so it just has to
find the filter the list belongs to and read said number. This is slower
than before, but a replacement function that just reads the internal numbers
that users are expected to switch to will be added soon; and furthermore,
avfilter_pad_count() is probably never called in hot loops anyway.

This saves about 49KiB from the binary; notice that these sentinels are
not in .bss despite being zeroed: they are in .data.rel.ro due to the
non-sentinels.

Reviewed-by: Nicolas George <george@nsup.org>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

1 files changed, 6 insertions, 12 deletions

diff --git a/libavfilter/vf_lut3d.c b/libavfilter/vf_lut3d.c
index 1246a5cab6..111e624dc3 100644
--- a/libavfilter/vf_lut3d.c
+++ b/libavfilter/vf_lut3d.c
@@ -1340,7 +1340,6 @@ static const AVFilterPad lut3d_inputs[] = {
         .filter_frame = filter_frame,
         .config_props = config_input,
     },
-    { NULL }
 };
 
 static const AVFilterPad lut3d_outputs[] = {
@@ -1348,7 +1347,6 @@ static const AVFilterPad lut3d_outputs[] = {
         .name = "default",
         .type = AVMEDIA_TYPE_VIDEO,
     },
-    { NULL }
 };
 
 const AVFilter ff_vf_lut3d = {
@@ -1358,8 +1356,8 @@ const AVFilter ff_vf_lut3d = {
     .init          = lut3d_init,
     .uninit        = lut3d_uninit,
     .query_formats = query_formats,
-    .inputs        = lut3d_inputs,
-    .outputs       = lut3d_outputs,
+    FILTER_INPUTS(lut3d_inputs),
+    FILTER_OUTPUTS(lut3d_outputs),
     .priv_class    = &lut3d_class,
     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
     .process_command = process_command,
@@ -1606,7 +1604,6 @@ static const AVFilterPad haldclut_inputs[] = {
         .type         = AVMEDIA_TYPE_VIDEO,
         .config_props = config_clut,
     },
-    { NULL }
 };
 
 static const AVFilterPad haldclut_outputs[] = {
@@ -1615,7 +1612,6 @@ static const AVFilterPad haldclut_outputs[] = {
         .type          = AVMEDIA_TYPE_VIDEO,
         .config_props  = config_output,
     },
-    { NULL }
 };
 
 const AVFilter ff_vf_haldclut = {
@@ -1627,8 +1623,8 @@ const AVFilter ff_vf_haldclut = {
     .uninit        = haldclut_uninit,
     .query_formats = query_formats,
     .activate      = activate,
-    .inputs        = haldclut_inputs,
-    .outputs       = haldclut_outputs,
+    FILTER_INPUTS(haldclut_inputs),
+    FILTER_OUTPUTS(haldclut_outputs),
     .priv_class    = &haldclut_class,
     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL | AVFILTER_FLAG_SLICE_THREADS,
     .process_command = process_command,
@@ -2273,7 +2269,6 @@ static const AVFilterPad lut1d_inputs[] = {
         .filter_frame = filter_frame_1d,
         .config_props = config_input_1d,
     },
-    { NULL }
 };
 
 static const AVFilterPad lut1d_outputs[] = {
@@ -2281,7 +2276,6 @@ static const AVFilterPad lut1d_outputs[] = {
         .name = "default",
         .type = AVMEDIA_TYPE_VIDEO,
     },
-    { NULL }
 };
 
 const AVFilter ff_vf_lut1d = {
@@ -2290,8 +2284,8 @@ const AVFilter ff_vf_lut1d = {
     .priv_size     = sizeof(LUT1DContext),
     .init          = lut1d_init,
     .query_formats = query_formats,
-    .inputs        = lut1d_inputs,
-    .outputs       = lut1d_outputs,
+    FILTER_INPUTS(lut1d_inputs),
+    FILTER_OUTPUTS(lut1d_outputs),
     .priv_class    = &lut1d_class,
     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
     .process_command = lut1d_process_command,