diff --git a/pkg/pcm/handlers.go b/pkg/pcm/handlers.go
index 39075199..18a96468 100644
--- a/pkg/pcm/handlers.go
+++ b/pkg/pcm/handlers.go
@@ -2,6 +2,7 @@ package pcm
 
 import (
 	"sync"
+	"time"
 
 	"github.com/AlexxIT/go2rtc/pkg/core"
 	"github.com/pion/rtp"
@@ -82,18 +83,27 @@ func TranscodeHandler(dst, src *core.Codec, handler core.HandlerFunc) core.Handl
 	}
 }
 
-func BytesPerFrame(codec *core.Codec) byte {
-	channels := byte(codec.Channels)
-	if channels == 0 {
-		channels = 1
-	}
-
+func BytesPerSample(codec *core.Codec) int {
 	switch codec.Name {
 	case core.CodecPCML, core.CodecPCM:
-		return 2 * channels
+		return 2
 	case core.CodecPCMU, core.CodecPCMA:
-		return channels
+		return 1
 	}
-
 	return 0
 }
+
+func BytesPerFrame(codec *core.Codec) int {
+	if codec.Channels <= 1 {
+		return BytesPerSample(codec)
+	}
+	return int(codec.Channels) * BytesPerSample(codec)
+}
+
+func FramesPerDuration(codec *core.Codec, duration time.Duration) int {
+	return int(time.Duration(codec.ClockRate) * duration / time.Second)
+}
+
+func BytesPerDuration(codec *core.Codec, duration time.Duration) int {
+	return BytesPerFrame(codec) * FramesPerDuration(codec, duration)
+}
diff --git a/pkg/pcm/pcm.go b/pkg/pcm/pcm.go
index 13405ad4..5395621e 100644
--- a/pkg/pcm/pcm.go
+++ b/pkg/pcm/pcm.go
@@ -1,13 +1,25 @@
 package pcm
 
-import "github.com/AlexxIT/go2rtc/pkg/core"
+import (
+	"math"
+
+	"github.com/AlexxIT/go2rtc/pkg/core"
+)
+
+func ceil(x float32) int {
+	d, fract := math.Modf(float64(x))
+	if fract == 0.0 {
+		return int(d)
+	}
+	return int(d) + 1
+}
 
 func Downsample(k float32) func([]int16) []int16 {
 	var sampleN, sampleSum float32
 
 	return func(src []int16) (dst []int16) {
 		var i int
-		dst = make([]int16, int((float32(len(src))+sampleN)/k))
+		dst = make([]int16, ceil((float32(len(src))+sampleN)/k))
 		for _, sample := range src {
 			sampleSum += float32(sample)
 			sampleN++
@@ -28,7 +40,7 @@ func Upsample(k float32) func([]int16) []int16 {
 
 	return func(src []int16) (dst []int16) {
 		var i int
-		dst = make([]int16, int(k*float32(len(src))))
+		dst = make([]int16, ceil(k*float32(len(src))))
 		for _, sample := range src {
 			sampleN += k
 			for sampleN > 0 {
diff --git a/pkg/pcm/producer_sync.go b/pkg/pcm/producer_sync.go
new file mode 100644
index 00000000..fedef268
--- /dev/null
+++ b/pkg/pcm/producer_sync.go
@@ -0,0 +1,96 @@
+package pcm
+
+import (
+	"io"
+	"time"
+
+	"github.com/AlexxIT/go2rtc/pkg/core"
+	"github.com/pion/rtp"
+)
+
+type ProducerSync struct {
+	core.Connection
+	src     *core.Codec
+	rd      io.Reader
+	onClose func()
+}
+
+func OpenSync(codec *core.Codec, rd io.Reader) *ProducerSync {
+	medias := []*core.Media{
+		{
+			Kind:      core.KindAudio,
+			Direction: core.DirectionRecvonly,
+			Codecs:    ProducerCodecs(),
+		},
+	}
+
+	return &ProducerSync{
+		Connection: core.Connection{
+			ID:         core.NewID(),
+			FormatName: "pcm",
+			Medias:     medias,
+			Transport:  rd,
+		},
+		src: codec,
+		rd:  rd,
+	}
+}
+
+func (p *ProducerSync) OnClose(f func()) {
+	p.onClose = f
+}
+
+func (p *ProducerSync) Start() error {
+	if len(p.Receivers) == 0 {
+		return nil
+	}
+
+	var pktSeq uint16
+	var pktTS uint32          // time in frames
+	var pktTime time.Duration // time in seconds
+
+	t0 := time.Now()
+
+	dst := p.Receivers[0].Codec
+	transcode := Transcode(dst, p.src)
+
+	const chunkDuration = 20 * time.Millisecond
+	chunkBytes := BytesPerDuration(p.src, chunkDuration)
+	chunkFrames := uint32(FramesPerDuration(dst, chunkDuration))
+
+	for {
+		buf := make([]byte, chunkBytes)
+		n, _ := io.ReadFull(p.rd, buf)
+
+		if n == 0 {
+			break
+		}
+
+		pkt := &core.Packet{
+			Header: rtp.Header{
+				Version:        2,
+				Marker:         true,
+				SequenceNumber: pktSeq,
+				Timestamp:      pktTS,
+			},
+			Payload: transcode(buf[:n]),
+		}
+
+		if d := pktTime - time.Since(t0); d > 0 {
+			time.Sleep(d)
+		}
+
+		p.Receivers[0].WriteRTP(pkt)
+		p.Recv += n
+
+		pktSeq++
+		pktTS += chunkFrames
+		pktTime += chunkDuration
+	}
+
+	if p.onClose != nil {
+		p.onClose()
+	}
+
+	return nil
+}
diff --git a/pkg/wav/producer.go b/pkg/wav/producer.go
index b9b3a878..60bdeaa1 100644
--- a/pkg/wav/producer.go
+++ b/pkg/wav/producer.go
@@ -2,7 +2,6 @@ package wav
 
 import (
 	"bufio"
-	"encoding/binary"
 	"errors"
 	"io"
 
@@ -17,39 +16,11 @@ func Open(r io.Reader) (*Producer, error) {
 	// https://www.mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/WAVE.html
 	rd := bufio.NewReaderSize(r, core.BufferSize)
 
-	// skip Master RIFF chunk
-	if _, err := rd.Discard(12); err != nil {
+	codec, err := ReadHeader(r)
+	if err != nil {
 		return nil, err
 	}
 
-	codec := &core.Codec{}
-
-	for {
-		chunkID, data, err := readChunk(rd)
-		if err != nil {
-			return nil, err
-		}
-
-		if chunkID == "data" {
-			break
-		}
-
-		if chunkID == "fmt " {
-			// https://audiocoding.cc/articles/2008-05-22-wav-file-structure/wav_formats.txt
-			switch data[0] {
-			case 1:
-				codec.Name = core.CodecPCML
-			case 6:
-				codec.Name = core.CodecPCMA
-			case 7:
-				codec.Name = core.CodecPCMU
-			}
-
-			codec.Channels = data[2]
-			codec.ClockRate = binary.LittleEndian.Uint32(data[4:])
-		}
-	}
-
 	if codec.Name == "" {
 		return nil, errors.New("waw: unsupported codec")
 	}
@@ -110,18 +81,3 @@ func (c *Producer) Start() error {
 		ts += PacketSize
 	}
 }
-
-func readChunk(r io.Reader) (chunkID string, data []byte, err error) {
-	b := make([]byte, 8)
-	if _, err = io.ReadFull(r, b); err != nil {
-		return
-	}
-
-	if chunkID = string(b[:4]); chunkID != "data" {
-		size := binary.LittleEndian.Uint32(b[4:])
-		data = make([]byte, size)
-		_, err = io.ReadFull(r, data)
-	}
-
-	return
-}
diff --git a/pkg/wav/wav.go b/pkg/wav/wav.go
index bf48fdf9..9fe857d4 100644
--- a/pkg/wav/wav.go
+++ b/pkg/wav/wav.go
@@ -2,6 +2,7 @@ package wav
 
 import (
 	"encoding/binary"
+	"io"
 
 	"github.com/AlexxIT/go2rtc/pkg/core"
 )
@@ -48,3 +49,55 @@ func Header(codec *core.Codec) []byte {
 
 	return b
 }
+
+func ReadHeader(r io.Reader) (*core.Codec, error) {
+	// skip Master RIFF chunk
+	if _, err := io.ReadFull(r, make([]byte, 12)); err != nil {
+		return nil, err
+	}
+
+	var codec core.Codec
+
+	for {
+		chunkID, data, err := readChunk(r)
+		if err != nil {
+			return nil, err
+		}
+
+		if chunkID == "data" {
+			break
+		}
+
+		if chunkID == "fmt " {
+			// https://audiocoding.cc/articles/2008-05-22-wav-file-structure/wav_formats.txt
+			switch data[0] {
+			case 1:
+				codec.Name = core.CodecPCML
+			case 6:
+				codec.Name = core.CodecPCMA
+			case 7:
+				codec.Name = core.CodecPCMU
+			}
+
+			codec.Channels = data[2]
+			codec.ClockRate = binary.LittleEndian.Uint32(data[4:])
+		}
+	}
+
+	return &codec, nil
+}
+
+func readChunk(r io.Reader) (chunkID string, data []byte, err error) {
+	b := make([]byte, 8)
+	if _, err = io.ReadFull(r, b); err != nil {
+		return
+	}
+
+	if chunkID = string(b[:4]); chunkID != "data" {
+		size := binary.LittleEndian.Uint32(b[4:])
+		data = make([]byte, size)
+		_, err = io.ReadFull(r, data)
+	}
+
+	return
+}
diff --git a/pkg/wyoming/expr.go b/pkg/wyoming/expr.go
index 1b184cc3..f2f58933 100644
--- a/pkg/wyoming/expr.go
+++ b/pkg/wyoming/expr.go
@@ -1,11 +1,13 @@
 package wyoming
 
 import (
+	"bytes"
 	"fmt"
+	"os"
 	"time"
 
 	"github.com/AlexxIT/go2rtc/pkg/expr"
-	"golang.org/x/net/context"
+	"github.com/AlexxIT/go2rtc/pkg/wav"
 )
 
 type env struct {
@@ -109,16 +111,21 @@ func (s *satellite) WriteEvent(args ...string) bool {
 }
 
 func (s *satellite) PlayAudio() bool {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
+	return s.playAudio(sndCodec, bytes.NewReader(s.sndAudio))
+}
 
-	prod := newSndProducer(s.sndAudio, cancel)
-	if err := s.srv.SndHandler(prod); err != nil {
+func (s *satellite) PlayFile(path string) bool {
+	f, err := os.Open(path)
+	if err != nil {
 		return false
-	} else {
-		<-ctx.Done()
-		return true
 	}
+
+	codec, err := wav.ReadHeader(f)
+	if err != nil {
+		return false
+	}
+
+	return s.playAudio(codec, f)
 }
 
 func (e *env) Sleep(s string) bool {
diff --git a/pkg/wyoming/satellite.go b/pkg/wyoming/satellite.go
index c45bc50e..0c0e6f30 100644
--- a/pkg/wyoming/satellite.go
+++ b/pkg/wyoming/satellite.go
@@ -1,10 +1,11 @@
 package wyoming
 
 import (
+	"context"
 	"fmt"
+	"io"
 	"net"
 	"sync"
-	"time"
 
 	"github.com/AlexxIT/go2rtc/pkg/core"
 	"github.com/AlexxIT/go2rtc/pkg/pcm"
@@ -55,13 +56,8 @@ func (s *Server) Handle(conn net.Conn) {
 			sat.sndAudio = sat.sndAudio[:0]
 		case "audio-chunk": // {"rate": 22050, "width": 2, "channels": 1, "timestamp": 0}
 			sat.sndAudio = append(sat.sndAudio, evt.Payload...)
-		}
-
-		if s.Event == nil || s.Event[evt.Type] == "" {
-			sat.handleEvent(evt)
-		} else {
-			// run async because there may be sleeps
-			go sat.handleScript(evt)
+		default:
+			sat.handleScript(evt)
 		}
 	}
 }
@@ -196,6 +192,21 @@ func (s *satellite) onMicChunk(chunk []byte) {
 	s.micTS += len(chunk) / 2
 }
 
+func (s *satellite) playAudio(codec *core.Codec, rd io.Reader) bool {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	prod := pcm.OpenSync(codec, rd)
+	prod.OnClose(cancel)
+
+	if err := s.srv.SndHandler(prod); err != nil {
+		return false
+	} else {
+		<-ctx.Done()
+		return true
+	}
+}
+
 type micConsumer struct {
 	core.Connection
 	onData  func(chunk []byte)
@@ -247,90 +258,6 @@ func (c *micConsumer) Stop() error {
 	return c.Connection.Stop()
 }
 
-type sndProducer struct {
-	core.Connection
-	data    []byte
-	onClose func()
-}
-
-func newSndProducer(data []byte, onClose func()) *sndProducer {
-	medias := []*core.Media{
-		{
-			Kind:      core.KindAudio,
-			Direction: core.DirectionRecvonly,
-			Codecs:    pcm.ProducerCodecs(),
-		},
-	}
-
-	return &sndProducer{
-		core.Connection{
-			ID:         core.NewID(),
-			FormatName: "wyoming",
-			Protocol:   "tcp",
-			Medias:     medias,
-		},
-		data,
-		onClose,
-	}
-}
-
-func (s *sndProducer) Start() error {
-	if len(s.Receivers) == 0 {
-		return nil
-	}
-
-	var pts time.Duration
-	var seq uint16
-
-	t0 := time.Now()
-
-	src := &core.Codec{Name: core.CodecPCML, ClockRate: 22050}
-	dst := s.Receivers[0].Codec
-	f := pcm.Transcode(dst, src)
-
-	bps := uint32(pcm.BytesPerFrame(dst))
-
-	chunkBytes := int(2 * src.ClockRate / 50) // 20ms
-
-	for {
-		n := len(s.data)
-		if n == 0 {
-			break
-		}
-		if chunkBytes > n {
-			chunkBytes = n
-		}
-
-		pkt := &core.Packet{
-			Header: rtp.Header{
-				Version:        2,
-				Marker:         true,
-				SequenceNumber: seq,
-				Timestamp:      uint32(s.Recv/2) * bps,
-			},
-			Payload: f(s.data[:chunkBytes]),
-		}
-
-		if d := pts - time.Since(t0); d > 0 {
-			time.Sleep(d)
-		}
-
-		s.Receivers[0].WriteRTP(pkt)
-
-		s.Recv += chunkBytes
-		s.data = s.data[chunkBytes:]
-
-		pts += 20 * time.Millisecond
-		seq++
-	}
-
-	if s.onClose != nil {
-		s.onClose()
-	}
-
-	return nil
-}
-
 func repack(handler core.HandlerFunc) core.HandlerFunc {
 	const PacketSize = 2 * 16000 / 50 // 20ms
 
diff --git a/pkg/wyoming/snd.go b/pkg/wyoming/snd.go
index 822c1ed4..e26ca7ea 100644
--- a/pkg/wyoming/snd.go
+++ b/pkg/wyoming/snd.go
@@ -1,8 +1,11 @@
 package wyoming
 
 import (
+	"bytes"
 	"net"
-	"time"
+
+	"github.com/AlexxIT/go2rtc/pkg/core"
+	"github.com/AlexxIT/go2rtc/pkg/pcm"
 )
 
 func (s *Server) HandleSnd(conn net.Conn) {
@@ -25,9 +28,7 @@ func (s *Server) HandleSnd(conn net.Conn) {
 		case "audio-chunk":
 			snd = append(snd, evt.Payload...)
 		case "audio-stop":
-			prod := newSndProducer(snd, func() {
-				time.Sleep(time.Second) // some extra delay before close
-			})
+			prod := pcm.OpenSync(sndCodec, bytes.NewReader(snd))
 			if err = s.SndHandler(prod); err != nil {
 				s.Error("snd error: %s", err)
 				return
@@ -35,3 +36,5 @@ func (s *Server) HandleSnd(conn net.Conn) {
 		}
 	}
 }
+
+var sndCodec = &core.Codec{Name: core.CodecPCML, ClockRate: 22050}