Added format context find best stream + compare timestamps

format_context.go

@@ -4,6 +4,7 @@ package astiav
 //#include <libavformat/avformat.h>
 import "C"
 import (
+	"fmt"
 	"math"
 	"unsafe"
 )
@@ -345,3 +346,21 @@ func (fc *FormatContext) SDPCreate() (string, error) {
 		return newError(C.av_sdp_create(&fccs[0], C.int(len(fccs)), buf, C.int(size)))
 	})
 }
+
+// https://ffmpeg.org/doxygen/7.0/avformat_8c.html#a8d4609a8f685ad894c1503ffd1b610b4
+func (fc *FormatContext) FindBestStream(mt MediaType, wantedStreamIndex, relatedStreamIndex int) (*Stream, *Codec, error) {
+	// Find best stream
+	var cCodec *C.AVCodec
+	ret := C.av_find_best_stream(fc.c, C.enum_AVMediaType(mt), C.int(wantedStreamIndex), C.int(relatedStreamIndex), &cCodec, 0)
+	if err := newError(ret); err != nil {
+		return nil, nil, err
+	}
+
+	// Loop through streams
+	for _, s := range fc.Streams() {
+		if s.Index() == int(ret) {
+			return s, newCodecFromC(cCodec), nil
+		}
+	}
+	return nil, nil, fmt.Errorf("astiav: no stream with index %d", ret)
+}

format_context_test.go

@@ -35,6 +35,16 @@ func TestFormatContext(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, "v=0\r\no=- 0 0 IN IP4 127.0.0.1\r\ns=Big Buck Bunny\r\nt=0 0\r\na=tool:libavformat 61.1.100\r\nm=video 0 RTP/AVP 96\r\nb=AS:441\r\na=rtpmap:96 H264/90000\r\na=fmtp:96 packetization-mode=1; sprop-parameter-sets=Z0LADasgKDPz4CIAAAMAAgAAAwBhHihUkA==,aM48gA==; profile-level-id=42C00D\r\na=control:streamid=0\r\nm=audio 0 RTP/AVP 97\r\nb=AS:161\r\na=rtpmap:97 MPEG4-GENERIC/48000/2\r\na=fmtp:97 profile-level-id=1;mode=AAC-hbr;sizelength=13;indexlength=3;indexdeltalength=3; config=1190\r\na=control:streamid=1\r\n", sdp)
 
+	_, _, err = fc1.FindBestStream(MediaTypeUnknown, -1, -1)
+	require.Error(t, err)
+	s2, c1, err := fc1.FindBestStream(MediaTypeVideo, -1, -1)
+	require.NoError(t, err)
+	require.Equal(t, s1.Index(), s2.Index())
+	require.Equal(t, s1.CodecParameters().CodecID(), c1.ID())
+	s2, c1, err = fc1.FindBestStream(MediaTypeAudio, 1, 0)
+	require.NoError(t, err)
+	require.Equal(t, 1, s2.Index())
+
 	fc2, err := AllocOutputFormatContext(nil, "mp4", "")
 	require.NoError(t, err)
 	defer fc2.Free()
@@ -43,20 +53,20 @@ func TestFormatContext(t *testing.T) {
 	fc3 := AllocFormatContext()
 	require.NotNil(t, fc3)
 	defer fc3.Free()
-	c, err := OpenIOContext("testdata/video.mp4", NewIOContextFlags(IOContextFlagRead))
+	io, err := OpenIOContext("testdata/video.mp4", NewIOContextFlags(IOContextFlagRead))
 	require.NoError(t, err)
-	defer c.Close() //nolint:errcheck
-	fc3.SetPb(c)
+	defer io.Close() //nolint:errcheck
+	fc3.SetPb(io)
 	fc3.SetStrictStdCompliance(StrictStdComplianceExperimental)
 	fc3.SetFlags(NewFormatContextFlags(FormatContextFlagAutoBsf))
 	require.NotNil(t, fc3.Pb())
 	require.Equal(t, StrictStdComplianceExperimental, fc3.StrictStdCompliance())
 	require.True(t, fc3.Flags().Has(FormatContextFlagAutoBsf))
-	s2 := fc3.NewStream(nil)
-	require.NotNil(t, s2)
 	s3 := fc3.NewStream(nil)
 	require.NotNil(t, s3)
-	require.Equal(t, 1, s3.Index())
+	s4 := fc3.NewStream(nil)
+	require.NotNil(t, s4)
+	require.Equal(t, 1, s4.Index())
 
 	d := NewDictionary()
 	d.Set("k", "v", 0)

time.go

@@ -20,3 +20,26 @@ var (
 func RelativeTime() int64 {
 	return int64(C.av_gettime_relative())
 }
+
+type CompareTimestampsResult uint8
+
+const (
+	CompareTimestampsResultUndefined CompareTimestampsResult = iota
+	CompareTimestampsResultAEqualB
+	CompareTimestampsResultABeforeB
+	CompareTimestampsResultAAfterB
+)
+
+// https://ffmpeg.org/doxygen/7.0/group__lavu__math.html#ga151744358fff630942b926e67e67c415
+func CompareTimestamps(a, b int64, timeBaseA, timeBaseB Rational) CompareTimestampsResult {
+	switch C.av_compare_ts(C.int64_t(a), timeBaseA.c, C.int64_t(b), timeBaseB.c) {
+	case C.int(-1):
+		return CompareTimestampsResultABeforeB
+	case C.int(0):
+		return CompareTimestampsResultAEqualB
+	case C.int(1):
+		return CompareTimestampsResultAAfterB
+	default:
+		return CompareTimestampsResultUndefined
+	}
+}

time_test.go

@@ -9,3 +9,15 @@ import (
 func TestTime(t *testing.T) {
 	require.NotEqual(t, 0, RelativeTime())
 }
+
+func TestCompareTimestamps(t *testing.T) {
+	a := int64(0)
+	timeBaseA := NewRational(1, 1)
+	b := int64(2)
+	timeBaseB := NewRational(1, 2)
+	require.Equal(t, CompareTimestampsResultABeforeB, CompareTimestamps(a, b, timeBaseA, timeBaseB))
+	a = 1
+	require.Equal(t, CompareTimestampsResultAEqualB, CompareTimestamps(a, b, timeBaseA, timeBaseB))
+	a = 2
+	require.Equal(t, CompareTimestampsResultAAfterB, CompareTimestamps(a, b, timeBaseA, timeBaseB))
+}