diff --git a/pkg/mp4/muxer.go b/pkg/mp4/muxer.go
index 485d8fc6..b1ec37f4 100644
--- a/pkg/mp4/muxer.go
+++ b/pkg/mp4/muxer.go
@@ -64,9 +64,11 @@ func (m *Muxer) GetInit(codecs []*core.Codec) ([]byte, error) {
 		switch codec.Name {
 		case core.CodecH264:
 			sps, pps := h264.GetParameterSet(codec.FmtpLine)
-			if sps == nil {
-				// some dummy SPS and PPS not a problem
+			// some dummy SPS and PPS not a problem
+			if len(sps) == 0 {
 				sps = []byte{0x67, 0x42, 0x00, 0x0a, 0xf8, 0x41, 0xa2}
+			}
+			if len(pps) == 0 {
 				pps = []byte{0x68, 0xce, 0x38, 0x80}
 			}
 
@@ -83,10 +85,14 @@ func (m *Muxer) GetInit(codecs []*core.Codec) ([]byte, error) {
 
 		case core.CodecH265:
 			vps, sps, pps := h265.GetParameterSet(codec.FmtpLine)
-			if sps == nil {
-				// some dummy SPS and PPS not a problem
+			// some dummy SPS and PPS not a problem
+			if len(vps) == 0 {
 				vps = []byte{0x40, 0x01, 0x0c, 0x01, 0xff, 0xff, 0x01, 0x40, 0x00, 0x00, 0x03, 0x00, 0x00, 0x03, 0x00, 0x00, 0x03, 0x00, 0x00, 0x03, 0x00, 0x99, 0xac, 0x09}
+			}
+			if len(sps) == 0 {
 				sps = []byte{0x42, 0x01, 0x01, 0x01, 0x40, 0x00, 0x00, 0x03, 0x00, 0x00, 0x03, 0x00, 0x00, 0x03, 0x00, 0x00, 0x03, 0x00, 0x99, 0xa0, 0x01, 0x40, 0x20, 0x05, 0xa1, 0xfe, 0x5a, 0xee, 0x46, 0xc1, 0xae, 0x55, 0x04}
+			}
+			if len(pps) == 0 {
 				pps = []byte{0x44, 0x01, 0xc0, 0x73, 0xc0, 0x4c, 0x90}
 			}