avfilter/formats: allow unknown channel layouts by default

Since the default in the libav fork is to only allow known layouts, making
unknown layouts allowed by default here can be a security risk for filters
directly merged from libav. However, usually it is simple to detect such cases,
use of av_get_channel_layout_nb_channels is a good indicator, so I suggest we
change this regardless.

See http://ffmpeg.org/pipermail/ffmpeg-devel/2016-November/203204.html.

This patch indirectly adds unknown channel layout support for filters where
query_formats is not specified:

abench
afifo
ainterleave
anullsink
apad
aperms
arealtime
aselect
asendcmd
asetnsamples
asetpts
asettb
ashowinfo
azmq

It introduces a query_formats callback for the asyncts filter, which only
supports known channel layouts since it is using libavresample.

And it removes .query_formats callback from filters where it was only there to
support unknown layouts, as this is now the default:

aloop
ametadata
anull
asidedata
asplit
atrim
Acked-by: Nicolas George <george@nsup.org>
Signed-off-by: Marton Balint <cus@passwd.hu>

libavfilter/af_anull.c

@@ -46,7 +46,6 @@ static const AVFilterPad avfilter_af_anull_outputs[] = {
 AVFilter ff_af_anull = {
     .name          = "anull",
     .description   = NULL_IF_CONFIG_SMALL("Pass the source unchanged to the output."),
-    .query_formats = ff_query_formats_all,
     .inputs        = avfilter_af_anull_inputs,
     .outputs       = avfilter_af_anull_outputs,
 };

libavfilter/af_asyncts.c

@@ -317,6 +317,7 @@ AVFilter ff_af_asyncts = {
     .uninit      = uninit,
     .priv_size   = sizeof(ASyncContext),
     .priv_class  = &asyncts_class,
+    .query_formats = ff_query_formats_all_layouts,
     .inputs      = avfilter_af_asyncts_inputs,
     .outputs     = avfilter_af_asyncts_outputs,
 };

libavfilter/f_loop.c

@@ -233,7 +233,6 @@ AVFilter ff_af_aloop = {
     .priv_size     = sizeof(LoopContext),
     .priv_class    = &aloop_class,
     .uninit        = auninit,
-    .query_formats = ff_query_formats_all,
     .inputs        = ainputs,
     .outputs       = aoutputs,
 };

libavfilter/f_metadata.c

@@ -373,7 +373,6 @@ AVFilter ff_af_ametadata = {
     .priv_class    = &ametadata_class,
     .init          = init,
     .uninit        = uninit,
-    .query_formats = ff_query_formats_all,
     .inputs        = ainputs,
     .outputs       = aoutputs,
     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,

libavfilter/f_sidedata.c

@@ -139,7 +139,6 @@ AVFilter ff_af_asidedata = {
     .priv_size     = sizeof(SideDataContext),
     .priv_class    = &asidedata_class,
     .init          = init,
-    .query_formats = ff_query_formats_all,
     .inputs        = ainputs,
     .outputs       = aoutputs,
     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,

libavfilter/formats.c

@@ -596,12 +596,12 @@ static int default_query_formats_common(AVFilterContext *ctx,
 
 int ff_default_query_formats(AVFilterContext *ctx)
 {
-    return default_query_formats_common(ctx, ff_all_channel_layouts);
+    return default_query_formats_common(ctx, ff_all_channel_counts);
 }
 
-int ff_query_formats_all(AVFilterContext *ctx)
+int ff_query_formats_all_layouts(AVFilterContext *ctx)
 {
-    return default_query_formats_common(ctx, ff_all_channel_counts);
+    return default_query_formats_common(ctx, ff_all_channel_layouts);
 }
 
 /* internal functions for parsing audio format arguments */

libavfilter/formats.h

@@ -186,15 +186,13 @@ void ff_channel_layouts_changeref(AVFilterChannelLayouts **oldref,
 av_warn_unused_result
 int ff_default_query_formats(AVFilterContext *ctx);
 
-/**
- * Set the formats list to all existing formats.
- * This function behaves like ff_default_query_formats(), except it also
- * accepts channel layouts with unknown disposition. It should only be used
- * with audio filters.
+ /**
+ * Set the formats list to all known channel layouts. This function behaves
+ * like ff_default_query_formats(), except it only accepts known channel
+ * layouts. It should only be used with audio filters.
  */
 av_warn_unused_result
-int ff_query_formats_all(AVFilterContext *ctx);
-
+int ff_query_formats_all_layouts(AVFilterContext *ctx);
 
 /**
  * Create a list of supported formats. This is intended for use in

libavfilter/split.c

@@ -144,7 +144,6 @@ AVFilter ff_af_asplit = {
     .priv_class  = &asplit_class,
     .init        = split_init,
     .uninit      = split_uninit,
-    .query_formats = ff_query_formats_all,
     .inputs      = avfilter_af_asplit_inputs,
     .outputs     = NULL,
     .flags       = AVFILTER_FLAG_DYNAMIC_OUTPUTS,

libavfilter/trim.c

@@ -365,7 +365,6 @@ AVFilter ff_af_atrim = {
     .name        = "atrim",
     .description = NULL_IF_CONFIG_SMALL("Pick one continuous section from the input, drop the rest."),
     .init        = init,
-    .query_formats = ff_query_formats_all,
     .priv_size   = sizeof(TrimContext),
     .priv_class  = &atrim_class,
     .inputs      = atrim_inputs,