diff --git a/filter_context.go b/filter_context.go
index 31ebc15..2a4e4b3 100644
--- a/filter_context.go
+++ b/filter_context.go
@@ -40,6 +40,18 @@ func (fc *FilterContext) Class() *Class {
 	return newClassFromC(unsafe.Pointer(fc.c))
 }
 
+// https://ffmpeg.org/doxygen/7.0/structAVFilterContext.html#addd946fbe5af506a2b19f9ad7cb97c35
+func (fc *FilterContext) SetHardwareDeviceContext(hdc *HardwareDeviceContext) {
+	if fc.c.hw_device_ctx != nil {
+		C.av_buffer_unref(&fc.c.hw_device_ctx)
+	}
+	if hdc != nil {
+		fc.c.hw_device_ctx = C.av_buffer_ref(hdc.c)
+	} else {
+		fc.c.hw_device_ctx = nil
+	}
+}
+
 // https://ffmpeg.org/doxygen/7.0/structAVFilterContext.html#a6eee53e57dddfa7cca1cade870c8a44e
 func (fc *FilterContext) Filter() *Filter {
 	return newFilterFromC(fc.c.filter)
diff --git a/filter_graph.go b/filter_graph.go
index 46ec6a2..bd26739 100644
--- a/filter_graph.go
+++ b/filter_graph.go
@@ -4,6 +4,7 @@ package astiav
 import "C"
 import (
 	"errors"
+	"math"
 	"unsafe"
 )
 
@@ -154,3 +155,17 @@ func (g *FilterGraph) SendCommand(target, cmd, args string, f FilterCommandFlags
 	})
 	return
 }
+
+// https://ffmpeg.org/doxygen/7.0/structAVFilterGraph.html#a0ba5c820c760788ea5f8e40c476f9704
+func (g *FilterGraph) NbFilters() int {
+	return int(g.c.nb_filters)
+}
+
+// https://ffmpeg.org/doxygen/7.0/structAVFilterGraph.html#a1dafd3d239f7c2f5e3ac109578ef926d
+func (g *FilterGraph) Filters() (fs []*FilterContext) {
+	fcs := (*[(math.MaxInt32 - 1) / unsafe.Sizeof((*C.AVFilterContext)(nil))](*C.AVFilterContext))(unsafe.Pointer(g.c.filters))
+	for i := 0; i < g.NbFilters(); i++ {
+		fs = append(fs, newFilterContext(fcs[i]))
+	}
+	return
+}
diff --git a/filter_graph_test.go b/filter_graph_test.go
index 9a5b6d2..c4a32a9 100644
--- a/filter_graph_test.go
+++ b/filter_graph_test.go
@@ -195,6 +195,14 @@ func TestFilterGraph(t *testing.T) {
 			outputs = o
 		}
 
+		require.Equal(t, len(buffersrcContexts)+1, fg.NbFilters())
+		fs := fg.Filters()
+		require.Equal(t, len(buffersrcContexts)+1, len(fs))
+		require.Equal(t, buffersinkContext.FilterContext(), fs[0])
+		for idx, c := range fs[1:] {
+			require.Equal(t, buffersrcContexts[idx].FilterContext(), c)
+		}
+
 		require.NoError(t, fg.Parse(v.content, inputs, outputs))
 		require.NoError(t, fg.Configure())