diff --git a/pkg/format/ac3.go b/pkg/format/ac3.go
index 3253202a..34c2811a 100644
--- a/pkg/format/ac3.go
+++ b/pkg/format/ac3.go
@@ -1,6 +1,7 @@
 package format
 
 import (
+	"fmt"
 	"strconv"
 	"strings"
 
@@ -23,15 +24,15 @@ func (f *AC3) unmarshal(ctx *unmarshalContext) error {
 	tmp := strings.SplitN(ctx.clock, "/", 2)
 
 	tmp1, err := strconv.ParseUint(tmp[0], 10, 31)
-	if err != nil {
-		return err
+	if err != nil || tmp1 == 0 {
+		return fmt.Errorf("invalid sample rate: '%s'", tmp[0])
 	}
 	f.SampleRate = int(tmp1)
 
 	if len(tmp) >= 2 {
 		tmp1, err := strconv.ParseUint(tmp[1], 10, 31)
-		if err != nil {
-			return err
+		if err != nil || tmp1 == 0 {
+			return fmt.Errorf("invalid channel count: '%s'", tmp[1])
 		}
 		f.ChannelCount = int(tmp1)
 	} else {
diff --git a/pkg/format/format_test.go b/pkg/format/format_test.go
index 66ae2abe..ca3195f4 100644
--- a/pkg/format/format_test.go
+++ b/pkg/format/format_test.go
@@ -1267,19 +1267,45 @@ func FuzzUnmarshal(f *testing.F) {
 		f.Add(ca.in)
 	}
 
-	f.Fuzz(func(_ *testing.T, in string) {
+	f.Fuzz(func(t *testing.T, in string) {
 		var desc sdp.SessionDescription
 		err := desc.Unmarshal([]byte(in))
+		if err != nil || len(desc.MediaDescriptions) == 0 || len(desc.MediaDescriptions[0].MediaName.Formats) == 0 {
+			return
+		}
 
-		if err == nil && len(desc.MediaDescriptions) >= 1 && len(desc.MediaDescriptions[0].MediaName.Formats) >= 1 {
-			f, err := Unmarshal(desc.MediaDescriptions[0], desc.MediaDescriptions[0].MediaName.Formats[0])
-			if err == nil {
-				f.Codec()
-				f.ClockRate()
-				f.PayloadType()
-				f.RTPMap()
-				f.FMTP()
-			}
+		f, err := Unmarshal(desc.MediaDescriptions[0], desc.MediaDescriptions[0].MediaName.Formats[0])
+		if err != nil {
+			return
+		}
+
+		// only Generic can return zero ClockRate
+		if _, ok := f.(*Generic); !ok {
+			require.NotZero(t, f.ClockRate())
+		} else {
+			f.ClockRate()
+		}
+
+		f.Codec()
+		f.PayloadType()
+		f.RTPMap()
+		f.FMTP()
+
+		switch f := f.(type) {
+		case *AC3:
+			require.NotZero(t, f.ChannelCount)
+
+		case *G711:
+			require.NotZero(t, f.ChannelCount)
+
+		case *LPCM:
+			require.NotZero(t, f.ChannelCount)
+
+		case *Opus:
+			require.NotZero(t, f.ChannelCount)
+
+		case *Vorbis:
+			require.NotZero(t, f.ChannelCount)
 		}
 	})
 }
diff --git a/pkg/format/g711.go b/pkg/format/g711.go
index f2f93883..f1baa81c 100644
--- a/pkg/format/g711.go
+++ b/pkg/format/g711.go
@@ -1,6 +1,7 @@
 package format
 
 import (
+	"fmt"
 	"strconv"
 	"strings"
 
@@ -40,15 +41,15 @@ func (f *G711) unmarshal(ctx *unmarshalContext) error {
 	tmp := strings.SplitN(ctx.clock, "/", 2)
 
 	tmp1, err := strconv.ParseUint(tmp[0], 10, 31)
-	if err != nil {
-		return err
+	if err != nil || tmp1 == 0 {
+		return fmt.Errorf("invalid sample rate: '%s'", tmp[0])
 	}
 	f.SampleRate = int(tmp1)
 
 	if len(tmp) >= 2 {
 		tmp1, err := strconv.ParseUint(tmp[1], 10, 31)
-		if err != nil {
-			return err
+		if err != nil || tmp1 == 0 {
+			return fmt.Errorf("invalid channel count: '%s'", tmp[1])
 		}
 		f.ChannelCount = int(tmp1)
 	} else {
diff --git a/pkg/format/lpcm.go b/pkg/format/lpcm.go
index a83d96a3..a0271d19 100644
--- a/pkg/format/lpcm.go
+++ b/pkg/format/lpcm.go
@@ -1,6 +1,7 @@
 package format
 
 import (
+	"fmt"
 	"strconv"
 	"strings"
 
@@ -50,15 +51,15 @@ func (f *LPCM) unmarshal(ctx *unmarshalContext) error {
 	tmp := strings.SplitN(ctx.clock, "/", 2)
 
 	tmp1, err := strconv.ParseUint(tmp[0], 10, 31)
-	if err != nil {
-		return err
+	if err != nil || tmp1 == 0 {
+		return fmt.Errorf("invalid sample rate: '%s'", tmp[0])
 	}
 	f.SampleRate = int(tmp1)
 
 	if len(tmp) >= 2 {
 		tmp1, err := strconv.ParseUint(tmp[1], 10, 31)
-		if err != nil {
-			return err
+		if err != nil || tmp1 == 0 {
+			return fmt.Errorf("invalid channel count: '%s'", tmp[1])
 		}
 		f.ChannelCount = int(tmp1)
 	} else {
diff --git a/pkg/format/opus.go b/pkg/format/opus.go
index 09902a4a..30a3a36a 100644
--- a/pkg/format/opus.go
+++ b/pkg/format/opus.go
@@ -65,10 +65,9 @@ func (f *Opus) unmarshal(ctx *unmarshalContext) error {
 		}
 
 		channelCount, err := strconv.ParseUint(tmp[1], 10, 31)
-		if err != nil {
+		if err != nil || channelCount == 0 {
 			return fmt.Errorf("invalid channel count: '%s'", tmp[1])
 		}
-
 		f.ChannelCount = int(channelCount)
 	}
 
diff --git a/pkg/format/speex.go b/pkg/format/speex.go
index 9dab74b2..ec1e9a24 100644
--- a/pkg/format/speex.go
+++ b/pkg/format/speex.go
@@ -19,8 +19,8 @@ func (f *Speex) unmarshal(ctx *unmarshalContext) error {
 	f.PayloadTyp = ctx.payloadType
 
 	sampleRate, err := strconv.ParseUint(ctx.clock, 10, 31)
-	if err != nil {
-		return err
+	if err != nil || sampleRate == 0 {
+		return fmt.Errorf("invalid sample rate: '%s'", ctx.clock)
 	}
 	f.SampleRate = int(sampleRate)
 
diff --git a/pkg/format/testdata/fuzz/FuzzUnmarshal/2910e512f655ed6b b/pkg/format/testdata/fuzz/FuzzUnmarshal/2910e512f655ed6b
new file mode 100644
index 00000000..d5abd780
--- /dev/null
+++ b/pkg/format/testdata/fuzz/FuzzUnmarshal/2910e512f655ed6b
@@ -0,0 +1,2 @@
+go test fuzz v1
+string("m=audio 0 AVP 96\na=rtpmap:96 VORBIS/0/0\na=fmtp:96 ConfigurAtion=")
diff --git a/pkg/format/testdata/fuzz/FuzzUnmarshal/2beaf42d3ab9327e b/pkg/format/testdata/fuzz/FuzzUnmarshal/2beaf42d3ab9327e
new file mode 100644
index 00000000..9123e8e4
--- /dev/null
+++ b/pkg/format/testdata/fuzz/FuzzUnmarshal/2beaf42d3ab9327e
@@ -0,0 +1,2 @@
+go test fuzz v1
+string("m=audio 0 AVP 97\na=rtpmap:97 L8/1/0")
diff --git a/pkg/format/testdata/fuzz/FuzzUnmarshal/2c9087410b17869e b/pkg/format/testdata/fuzz/FuzzUnmarshal/2c9087410b17869e
new file mode 100644
index 00000000..268776af
--- /dev/null
+++ b/pkg/format/testdata/fuzz/FuzzUnmarshal/2c9087410b17869e
@@ -0,0 +1,2 @@
+go test fuzz v1
+string("m=audio 0 AVP 96\na=rtpmap:96 PCMA/1/0")
diff --git a/pkg/format/testdata/fuzz/FuzzUnmarshal/5c81ab28bdb170e5 b/pkg/format/testdata/fuzz/FuzzUnmarshal/5c81ab28bdb170e5
new file mode 100644
index 00000000..f1080142
--- /dev/null
+++ b/pkg/format/testdata/fuzz/FuzzUnmarshal/5c81ab28bdb170e5
@@ -0,0 +1,2 @@
+go test fuzz v1
+string("m=audio 0 AVP 97\na=rtpmap:97 AC3/0")
diff --git a/pkg/format/testdata/fuzz/FuzzUnmarshal/6d4ccd096ae9afd2 b/pkg/format/testdata/fuzz/FuzzUnmarshal/6d4ccd096ae9afd2
new file mode 100644
index 00000000..dd874637
--- /dev/null
+++ b/pkg/format/testdata/fuzz/FuzzUnmarshal/6d4ccd096ae9afd2
@@ -0,0 +1,2 @@
+go test fuzz v1
+string("m=audio 0 AVP 96\na=rtpmap:96 AC3/1/0")
diff --git a/pkg/format/testdata/fuzz/FuzzUnmarshal/72052247f0539111 b/pkg/format/testdata/fuzz/FuzzUnmarshal/72052247f0539111
new file mode 100644
index 00000000..c1bb35f2
--- /dev/null
+++ b/pkg/format/testdata/fuzz/FuzzUnmarshal/72052247f0539111
@@ -0,0 +1,2 @@
+go test fuzz v1
+string("m=audio 0 AVP 96\na=rtpmap:96 multiopus/48000/0")
diff --git a/pkg/format/testdata/fuzz/FuzzUnmarshal/930d7278501087f2 b/pkg/format/testdata/fuzz/FuzzUnmarshal/930d7278501087f2
new file mode 100644
index 00000000..50a8f677
--- /dev/null
+++ b/pkg/format/testdata/fuzz/FuzzUnmarshal/930d7278501087f2
@@ -0,0 +1,2 @@
+go test fuzz v1
+string("m=audio 0 AVP 96\na=rtpmap:96 VORBIS/1/0\na=fmtp:96 ConfigurAtion=")
diff --git a/pkg/format/testdata/fuzz/FuzzUnmarshal/b1a3816de12e306d b/pkg/format/testdata/fuzz/FuzzUnmarshal/b1a3816de12e306d
new file mode 100644
index 00000000..66a56a26
--- /dev/null
+++ b/pkg/format/testdata/fuzz/FuzzUnmarshal/b1a3816de12e306d
@@ -0,0 +1,2 @@
+go test fuzz v1
+string("m=audio 0 AVP 96\na=rtpmap:96 speeX/0")
diff --git a/pkg/format/testdata/fuzz/FuzzUnmarshal/c3f02e1806e34919 b/pkg/format/testdata/fuzz/FuzzUnmarshal/c3f02e1806e34919
new file mode 100644
index 00000000..f228472d
--- /dev/null
+++ b/pkg/format/testdata/fuzz/FuzzUnmarshal/c3f02e1806e34919
@@ -0,0 +1,2 @@
+go test fuzz v1
+string("m=audio 0 AVP 97\na=rtpmap:97 L16/0")
diff --git a/pkg/format/vorbis.go b/pkg/format/vorbis.go
index 9d5d8017..d595960d 100644
--- a/pkg/format/vorbis.go
+++ b/pkg/format/vorbis.go
@@ -27,14 +27,14 @@ func (f *Vorbis) unmarshal(ctx *unmarshalContext) error {
 	}
 
 	sampleRate, err := strconv.ParseUint(tmp[0], 10, 31)
-	if err != nil {
-		return err
+	if err != nil || sampleRate == 0 {
+		return fmt.Errorf("invalid sample rate: '%s'", tmp[0])
 	}
 	f.SampleRate = int(sampleRate)
 
 	channelCount, err := strconv.ParseUint(tmp[1], 10, 31)
-	if err != nil {
-		return err
+	if err != nil || channelCount == 0 {
+		return fmt.Errorf("invalid channel count: '%s'", tmp[1])
 	}
 	f.ChannelCount = int(channelCount)