fix(ffmpeg): no codec handling

ffmpeg/ffmpeg.go

@@ -85,6 +85,9 @@ func LoadAVContext(ctx context.Context, reader io.Reader, size int64) (*AVContex
 }
 
 func (av *AVContext) ProcessFrames(maxFrames int) (err error) {
+	if av.formatContext == nil || av.codecContext == nil {
+		return ErrDecoderNotFound
+	}
 	if av.thumbContext == nil {
 		return createThumbContext(av, C.int(maxFrames))
 	}

processor_test.go

@@ -55,6 +55,8 @@ func TestProcessor(t *testing.T) {
 		{name: "image", path: "fit-in/100x100/demo.png"},
 		{name: "alpha", path: "fit-in/filters:format(png)/alpha-webm.webm"},
 		{name: "corrupted", path: "fit-in/100x100/corrupt/everybody-betray-me.mkv", expectCode: 406},
+		{name: "no cover meta", path: "meta/no_cover.mp3"},
+		{name: "no cover 406", path: "fit-in/100x100/no_cover.mp3", expectCode: 406},
 	}, WithDebug(true), WithLogger(zap.NewExample()))
 	doGoldenTests(t, filepath.Join(testDataDir, "golden/result-fallback-image"), []test{
 		{name: "corrupted with fallback image", path: "fit-in/100x100/corrupt/everybody-betray-me.mkv", expectCode: 406},

testdata/golden/result/meta/no_cover.mp3

@@ -0,0 +1 @@
+{"format":"mp3","content_type":"audio/mpeg","orientation":0,"duration":13536,"has_video":false,"has_audio":true}