diff --git a/format_go112.go b/format_go112.go
index 4665fe3..d1044e5 100644
--- a/format_go112.go
+++ b/format_go112.go
@@ -380,6 +380,40 @@ func (ctx *FmtCtx) GetNextPacketForStreamIndex(streamIndex int) (*Packet, error)
 	}
 }
 
+func (ctx *FmtCtx) GetFirstPacketForStreamIndex(streamIndex int) (*Packet, error) {
+	currentPacket, err := ctx.GetNextPacketForStreamIndex(streamIndex)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get current packet: %s", err)
+	}
+	originalPosition := currentPacket.Pos()
+
+	err = ctx.SeekFrameAt(0, streamIndex)
+	if err != nil {
+		return nil, fmt.Errorf("failed to seek to first frame: %s", err)
+	}
+
+	packet, err := ctx.GetNextPacketForStreamIndex(streamIndex)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get next packet: %s", err)
+	}
+
+	err = ctx.SeekFrameAt(originalPosition, streamIndex)
+	if err != nil {
+		return nil, fmt.Errorf("failed to seek to original position: %s", err)
+	}
+
+	return packet, nil
+}
+
+func (ctx *FmtCtx) GetLastPacketForStreamIndex(streamIndex int) (*Packet, error) {
+	err := ctx.SeekFrameAt(int64(ctx.Duration()), streamIndex)
+	if err != nil {
+		return nil, fmt.Errorf("failed to seek to last frame: %s", err)
+	}
+
+	return ctx.GetNextPacketForStreamIndex(streamIndex)
+}
+
 func (ctx *FmtCtx) GetNewPackets() chan *Packet {
 	yield := make(chan *Packet)
 
@@ -572,25 +606,76 @@ func (ctx *FmtCtx) SeekFrameAtTimeCode(timecode string, streamIndex int) error {
 	istCodecCtx := ist.CodecCtx()
 	istAvgFrameRate := ist.GetAvgFrameRate()
 
-	sec := int64(0)
+	// check if timecode is valid (i.e. if the timecode is between the first and last frame of the video)
+	firstPacket, err := ctx.GetFirstPacketForStreamIndex(streamIndex)
+	if err != nil {
+		return err
+	}
+	lastPacket, err := ctx.GetLastPacketForStreamIndex(streamIndex)
+	if err != nil {
+		return err
+	}
+	firstFrameTimeCode, err := getPacketTimeCode(firstPacket, istCodecCtx, istAvgFrameRate)
+	if err != nil {
+		return err
+	}
+	lastFrameTimeCode, err := getPacketTimeCode(lastPacket, istCodecCtx, istAvgFrameRate)
+	if err != nil {
+		return err
+	}
+
+	tcBetween, err := IsTimeCodeBetween(timecode, firstFrameTimeCode, lastFrameTimeCode)
+	if err != nil {
+		return err
+	}
+	if !tcBetween {
+		return errors.New("timecode is not between the first and last frame of the video")
+	}
+
+	// get comparable timecodes
+	hhToTest, hhStart, hhEnd, err := TimeCodeToComparable(timecode, firstFrameTimeCode, lastFrameTimeCode)
+	if err != nil {
+		return err
+	}
+
+	// calculate a good approximation of the position of the needed frame
+	var relativePos float64 = float64(float64(hhToTest-hhStart) / float64(hhEnd-hhStart))
+
+	// rewind a bit to be sure we are not too far
+	if relativePos-0.001 > 0 {
+		relativePos -= 0.001
+	}
+
+	sec := ctx.Duration() * relativePos
+	err = ctx.SeekFrameAt(int64(sec), streamIndex)
+	if err != nil {
+		return err
+	}
 
 	found := false
 	for !found {
-		packet, err := ctx.GetNextPacket()
+		packet, err := ctx.GetNextPacketForStreamIndex(streamIndex)
 		if err != nil {
 			return err
 		}
-		if packet.StreamIndex() != streamIndex {
-			continue
-		}
 
-		found, err = isPacketLaterThanTimeCode(packet, timecode, istCodecCtx, istAvgFrameRate)
+		frameTimeCode, err := getPacketTimeCode(packet, istCodecCtx, istAvgFrameRate)
 		if err != nil {
 			return err
 		}
-		if !found {
-			sec += 5
-			err = ctx.SeekFrameAt(sec, streamIndex)
+
+		hhFrameTimeCode, _, _, err := TimeCodeToComparable(frameTimeCode, firstFrameTimeCode, lastFrameTimeCode)
+		if err != nil {
+			return err
+		}
+
+		if hhFrameTimeCode >= hhToTest {
+			return nil
+		}
+
+		if hhFrameTimeCode < hhToTest {
+			sec += 1
+			err = ctx.SeekFrameAt(int64(sec), streamIndex)
 			if err != nil {
 				return err
 			}
diff --git a/go.mod b/go.mod
index a358606..a011dd5 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,5 @@
 module github.com/3d0c/gmf
 
 go 1.12
+
+require github.com/stretchr/testify v1.7.1
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..2dca7c9
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,11 @@
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.7.1 h1:5TQK59W5E3v0r2duFAb7P95B6hEeOyEnHRa8MjYSMTY=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/utils.go b/utils.go
index 5acf3de..6241a66 100644
--- a/utils.go
+++ b/utils.go
@@ -27,6 +27,8 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
+	"strconv"
+	"strings"
 	"syscall"
 	"unsafe"
 )
@@ -184,3 +186,69 @@ func GenSyntVideoN(N, w, h int, fmt int32) chan *Frame {
 	}()
 	return yield
 }
+
+func TimeCodeToComparable(timeCodeToTest, timeCodeStart, timeCodeEnd string) (hhToTest int, hhStart int, hhEnd int, err error) {
+	hhStart, err = TimeCodeToHundredths(timeCodeStart)
+	if err != nil {
+		return
+	}
+	hhEnd, err = TimeCodeToHundredths(timeCodeEnd)
+	if err != nil {
+		return
+	}
+	hhToTest, err = TimeCodeToHundredths(timeCodeToTest)
+	if err != nil {
+		return
+	}
+
+	if hhEnd < hhStart {
+		hhStart -= hhEnd
+		hhToTest -= hhEnd
+		if hhToTest <= 0 {
+			hhToTest += 24 * 60 * 60 * 100
+		}
+		hhEnd = 24 * 60 * 60 * 100
+	}
+	return
+}
+
+func IsTimeCodeBetween(timeCodeToTest, timeCodeStart, timeCodeEnd string) (bool, error) {
+	hhToTest, hhStart, hhEnd, err := TimeCodeToComparable(timeCodeToTest, timeCodeStart, timeCodeEnd)
+	if err != nil {
+		return false, err
+	}
+	return hhToTest >= hhStart && hhToTest <= hhEnd, nil
+}
+
+// TimeCodeToHHMMSS splits a timeCode = "20:15:31:00" to return 20, 15, 31
+func TimeCodeToHHMMSS(timeCode string) (int, int, int, int, error) {
+	parts := strings.Split(timeCode, ":")
+	if len(parts) != 4 {
+		return -1, -1, -1, -1, errors.New("invalid timecode")
+	}
+	hh, err := strconv.Atoi(parts[0])
+	if err != nil {
+		return -1, -1, -1, -1, errors.New("invalid timecode")
+	}
+	mm, err := strconv.Atoi(parts[1])
+	if err != nil {
+		return -1, -1, -1, -1, errors.New("invalid timecode")
+	}
+	ss, err := strconv.Atoi(parts[2])
+	if err != nil {
+		return -1, -1, -1, -1, errors.New("invalid timecode")
+	}
+	hs, err := strconv.Atoi(parts[3])
+	if err != nil {
+		return -1, -1, -1, -1, errors.New("invalid timecode")
+	}
+	return hh, mm, ss, hs, nil
+}
+
+func TimeCodeToHundredths(timeCode string) (int, error) {
+	hh, mm, ss, hs, err := TimeCodeToHHMMSS(timeCode)
+	if err != nil {
+		return -1, err
+	}
+	return (hh * 60 * 60 * 100) + (mm * 60 * 100) + (ss * 100) + hs, nil
+}
diff --git a/utils_test.go b/utils_test.go
index e873d52..bf2cdb5 100644
--- a/utils_test.go
+++ b/utils_test.go
@@ -1,8 +1,10 @@
 package gmf_test
 
 import (
-	"github.com/3d0c/gmf"
 	"testing"
+
+	"github.com/3d0c/gmf"
+	"github.com/stretchr/testify/require"
 )
 
 func TestAvError(t *testing.T) {
@@ -10,3 +12,34 @@ func TestAvError(t *testing.T) {
 		t.Fatalf("Expected error is 'No such file or directory', '%s' got\n", err.Error())
 	}
 }
+
+func TestIsTimeCodeBetween(t *testing.T) {
+	timeCodeStart := "20:31:00:62"
+	timeCodeEnd := "04:56:12:00"
+	tests := []struct {
+		timeCodeToTest string
+		expectedBool   bool
+		errorExpected  bool
+	}{
+		{"20:15:31:00", false, false},
+		{"20:30:59:99", false, false},
+		{"20:30:59:99", false, false},
+		{"20:31:00:00", false, false},
+		{"20:31:00:61", false, false},
+		{"20:31:31:62", true, false},
+		{"04:31:31:00", true, false},
+		{"04:56:12:00", true, false},
+		{"04:56:12:01", false, false},
+		{"05:31:31:00", false, false},
+		{"05:31:31", false, true},
+	}
+	for _, test := range tests {
+		isTimeCodeBetween, err := gmf.IsTimeCodeBetween(test.timeCodeToTest, timeCodeStart, timeCodeEnd)
+		if test.errorExpected {
+			require.Error(t, err)
+		} else {
+			require.NoError(t, err)
+		}
+		require.Equal(t, test.expectedBool, isTimeCodeBetween, "hourToTest: %s", test.timeCodeToTest)
+	}
+}