Now removing from classers after the free method

bit_stream_filter_context.go

@@ -60,8 +60,15 @@ func (bsfc *BitStreamFilterContext) ReceivePacket(p *Packet) error {
 }
 
 func (bsfc *BitStreamFilterContext) Free() {
-	classers.del(bsfc)
+	if bsfc.c != nil {
+		// Make sure to clone the classer before freeing the object since
+		// the C free method resets the pointer
+		c := newClonedClasser(bsfc)
 		C.av_bsf_free(&bsfc.c)
+		// Make sure to remove from classers after freeing the object since
+		// the C free method may use methods needing the classer
+		classers.del(c)
+	}
 }
 
 func (bsfc *BitStreamFilterContext) InputTimeBase() Rational {

class.go

@@ -52,6 +52,8 @@ type Classer interface {
 	Class() *Class
 }
 
+var _ Classer = (*UnknownClasser)(nil)
+
 type UnknownClasser struct {
 	c *Class
 }
@@ -64,6 +66,24 @@ func (c *UnknownClasser) Class() *Class {
 	return c.c
 }
 
+var _ Classer = (*ClonedClasser)(nil)
+
+type ClonedClasser struct {
+	c *Class
+}
+
+func newClonedClasser(c Classer) *ClonedClasser {
+	cl := c.Class()
+	if cl == nil {
+		return nil
+	}
+	return &ClonedClasser{c: newClassFromC(cl.ptr)}
+}
+
+func (c *ClonedClasser) Class() *Class {
+	return c.c
+}
+
 var classers = newClasserPool()
 
 type classerPool struct {

class_test.go

@@ -31,6 +31,10 @@ func TestClassers(t *testing.T) {
 	f := AllocFilterGraph()
 	c := FindDecoder(CodecIDMjpeg)
 	require.NotNil(t, c)
+	bf := FindBitStreamFilterByName("null")
+	require.NotNil(t, bf)
+	bfc, err := AllocBitStreamFilterContext(bf)
+	require.NoError(t, err)
 	cc := AllocCodecContext(c)
 	require.NotNil(t, cc)
 	bufferSink := FindFilterByName("buffersink")
@@ -41,23 +45,27 @@ func TestClassers(t *testing.T) {
 	fmc2 := AllocFormatContext()
 	require.NoError(t, fmc2.OpenInput("testdata/video.mp4", nil, nil))
 	path := filepath.Join(t.TempDir(), "iocontext.txt")
-	ic, err := OpenIOContext(path, NewIOContextFlags(IOContextFlagWrite))
+	ic1, err := OpenIOContext(path, NewIOContextFlags(IOContextFlagWrite))
 	require.NoError(t, err)
 	defer os.RemoveAll(path)
+	ic2, err := AllocIOContext(1, true, nil, nil, nil)
+	require.NoError(t, err)
 	ssc, err := CreateSoftwareScaleContext(1, 1, PixelFormatRgba, 2, 2, PixelFormatRgba, NewSoftwareScaleContextFlags())
 	require.NoError(t, err)
 
-	require.Equal(t, cl+8, len(classers.p))
+	require.Equal(t, cl+10, len(classers.p))
 	v, ok := classers.get(unsafe.Pointer(f.c))
 	require.True(t, ok)
 	require.Equal(t, f, v)
 
+	bfc.Free()
 	cc.Free()
 	fc.Free()
 	f.Free()
 	fmc1.Free()
 	fmc2.CloseInput()
-	require.NoError(t, ic.Close())
+	require.NoError(t, ic1.Close())
+	ic2.Free()
 	ssc.Free()
 	require.Equal(t, cl, len(classers.p))
 }

codec_context.go

@@ -38,8 +38,15 @@ func (cc *CodecContext) Free() {
 		C.av_buffer_unref(&cc.hdc.c)
 		cc.hdc = nil
 	}
-	classers.del(cc)
+	if cc.c != nil {
+		// Make sure to clone the classer before freeing the object since
+		// the C free method resets the pointer
+		c := newClonedClasser(cc)
 		C.avcodec_free_context(&cc.c)
+		// Make sure to remove from classers after freeing the object since
+		// the C free method may use methods needing the classer
+		classers.del(c)
+	}
 }
 
 func (cc *CodecContext) String() string {

filter_context.go

@@ -27,8 +27,10 @@ func newFilterContext(c *C.AVFilterContext) *FilterContext {
 var _ Classer = (*FilterContext)(nil)
 
 func (fc *FilterContext) Free() {
-	classers.del(fc)
 	C.avfilter_free(fc.c)
+	// Make sure to remove from classers after freeing the object since
+	// the C free method may use methods needing the classer
+	classers.del(fc)
 }
 
 func (fc *FilterContext) BuffersrcAddFrame(f *Frame, fs BuffersrcFlags) error {

filter_graph.go

@@ -28,9 +28,14 @@ func AllocFilterGraph() *FilterGraph {
 }
 
 func (g *FilterGraph) Free() {
-	classers.del(g)
 	if g.c != nil {
+		// Make sure to clone the classer before freeing the object since
+		// the C free method resets the pointer
+		c := newClonedClasser(g)
 		C.avfilter_graph_free(&g.c)
+		// Make sure to remove from classers after freeing the object since
+		// the C free method may use methods needing the classer
+		classers.del(c)
 	}
 }
 

format_context.go

@@ -51,8 +51,10 @@ func AllocOutputFormatContext(of *OutputFormat, formatName, filename string) (*F
 }
 
 func (fc *FormatContext) Free() {
-	classers.del(fc)
 	C.avformat_free_context(fc.c)
+	// Make sure to remove from classers after freeing the object since
+	// the C free method may use methods needing the classer
+	classers.del(fc)
 }
 
 func (fc *FormatContext) BitRate() int64 {
@@ -192,12 +194,18 @@ func (fc *FormatContext) OpenInput(url string, fmt *InputFormat, d *Dictionary)
 }
 
 func (fc *FormatContext) CloseInput() {
-	if pb := fc.Pb(); pb != nil {
+	pb := fc.Pb()
+	if fc.c != nil {
+		// Make sure to clone the classer before freeing the object since
+		// the C free method resets the pointer
+		c := newClonedClasser(fc)
+		C.avformat_close_input(&fc.c)
+		// Make sure to remove from classers after freeing the object since
+		// the C free method may use methods needing the classer
+		if pb != nil {
 			classers.del(pb)
 		}
-	classers.del(fc)
-	if fc.c != nil {
-		C.avformat_close_input(&fc.c)
+		classers.del(c)
 	}
 }
 

io_context.go

@@ -122,15 +122,21 @@ func (ic *IOContext) Class() *Class {
 }
 
 func (ic *IOContext) Close() error {
-	classers.del(ic)
 	if ic.c != nil {
-		return newError(C.avio_closep(&ic.c))
+		// Make sure to clone the classer before freeing the object since
+		// the C free method resets the pointer
+		c := newClonedClasser(ic)
+		if err := newError(C.avio_closep(&ic.c)); err != nil {
+			return err
+		}
+		// Make sure to remove from classers after freeing the object since
+		// the C free method may use methods needing the classer
+		classers.del(c)
 	}
 	return nil
 }
 
 func (ic *IOContext) Free() {
-	classers.del(ic)
 	if ic.c != nil {
 		if ic.c.buffer != nil {
 			C.av_freep(unsafe.Pointer(&ic.c.buffer))
@@ -139,7 +145,13 @@ func (ic *IOContext) Free() {
 			C.free(ic.handlerID)
 			ic.handlerID = nil
 		}
+		// Make sure to clone the classer before freeing the object since
+		// the C free method resets the pointer
+		c := newClonedClasser(ic)
 		C.avio_context_free(&ic.c)
+		// Make sure to remove from classers after freeing the object since
+		// the C free method may use methods needing the classer
+		classers.del(c)
 	}
 	return
 }

software_scale_context.go

@@ -60,8 +60,13 @@ func CreateSoftwareScaleContext(srcW, srcH int, srcFormat PixelFormat, dstW, dst
 }
 
 func (ssc *SoftwareScaleContext) Free() {
-	classers.del(ssc)
+	// Make sure to clone the classer before freeing the object since
+	// the C free method may reset the pointer
+	c := newClonedClasser(ssc)
 	C.sws_freeContext(ssc.c)
+	// Make sure to remove from classers after freeing the object since
+	// the C free method may use methods needing the classer
+	classers.del(c)
 }
 
 var _ Classer = (*SoftwareScaleContext)(nil)