mediamtx/internal/hls/fmp4/init_track.go

package fmp4

import (
	gomp4 "github.com/abema/go-mp4"
	"github.com/aler9/gortsplib/v2/pkg/format"
	"github.com/aler9/gortsplib/v2/pkg/h264"
)

// InitTrack is a track of Init.
type InitTrack struct {
	ID        int
	TimeScale uint32
	Format    format.Format
}

func (track *InitTrack) marshal(w *mp4Writer) error {
	/*
	   trak
	   - tkhd
	   - mdia
	     - mdhd
	     - hdlr
	     - minf
	       - vmhd (video only)
	       - smhd (audio only)
	       - dinf
	         - dref
	           - url
	       - stbl
	         - stsd
	           - avc1 (h264 only)
	             - avcC
	             - pasp
	             - btrt
	           - mp4a (mpeg4audio only)
	             - esds
	             - btrt
	         - stts
	         - stsc
	         - stsz
	         - stco
	*/

	_, err := w.writeBoxStart(&gomp4.Trak{}) // <trak>
	if err != nil {
		return err
	}

	var sps []byte
	var pps []byte
	var spsp h264.SPS
	var width int
	var height int

	switch ttrack := track.Format.(type) {
	case *format.H264:
		sps = ttrack.SafeSPS()
		pps = ttrack.SafePPS()

		err = spsp.Unmarshal(sps)
		if err != nil {
			return err
		}

		width = spsp.Width()
		height = spsp.Height()

		_, err = w.WriteBox(&gomp4.Tkhd{ // <tkhd/>
			FullBox: gomp4.FullBox{
				Flags: [3]byte{0, 0, 3},
			},
			TrackID: uint32(track.ID),
			Width:   uint32(width * 65536),
			Height:  uint32(height * 65536),
			Matrix:  [9]int32{0x00010000, 0, 0, 0, 0x00010000, 0, 0, 0, 0x40000000},
		})
		if err != nil {
			return err
		}

	case *format.MPEG4Audio:
		_, err = w.WriteBox(&gomp4.Tkhd{ // <tkhd/>
			FullBox: gomp4.FullBox{
				Flags: [3]byte{0, 0, 3},
			},
			TrackID:        uint32(track.ID),
			AlternateGroup: 1,
			Volume:         256,
			Matrix:         [9]int32{0x00010000, 0, 0, 0, 0x00010000, 0, 0, 0, 0x40000000},
		})
		if err != nil {
			return err
		}
	}

	_, err = w.writeBoxStart(&gomp4.Mdia{}) // <mdia>
	if err != nil {
		return err
	}

	_, err = w.WriteBox(&gomp4.Mdhd{ // <mdhd/>
		Timescale: track.TimeScale,
		Language:  [3]byte{'u', 'n', 'd'},
	})
	if err != nil {
		return err
	}

	switch track.Format.(type) {
	case *format.H264:
		_, err = w.WriteBox(&gomp4.Hdlr{ // <hdlr/>
			HandlerType: [4]byte{'v', 'i', 'd', 'e'},
			Name:        "VideoHandler",
		})
		if err != nil {
			return err
		}

	case *format.MPEG4Audio:
		_, err = w.WriteBox(&gomp4.Hdlr{ // <hdlr/>
			HandlerType: [4]byte{'s', 'o', 'u', 'n'},
			Name:        "SoundHandler",
		})
		if err != nil {
			return err
		}
	}

	_, err = w.writeBoxStart(&gomp4.Minf{}) // <minf>
	if err != nil {
		return err
	}

	switch track.Format.(type) {
	case *format.H264:
		_, err = w.WriteBox(&gomp4.Vmhd{ // <vmhd/>
			FullBox: gomp4.FullBox{
				Flags: [3]byte{0, 0, 1},
			},
		})
		if err != nil {
			return err
		}

	case *format.MPEG4Audio:
		_, err = w.WriteBox(&gomp4.Smhd{ // <smhd/>
		})
		if err != nil {
			return err
		}
	}

	_, err = w.writeBoxStart(&gomp4.Dinf{}) // <dinf>
	if err != nil {
		return err
	}

	_, err = w.writeBoxStart(&gomp4.Dref{ // <dref>
		EntryCount: 1,
	})
	if err != nil {
		return err
	}

	_, err = w.WriteBox(&gomp4.Url{ // <url/>
		FullBox: gomp4.FullBox{
			Flags: [3]byte{0, 0, 1},
		},
	})
	if err != nil {
		return err
	}

	err = w.writeBoxEnd() // </dref>
	if err != nil {
		return err
	}

	err = w.writeBoxEnd() // </dinf>
	if err != nil {
		return err
	}

	_, err = w.writeBoxStart(&gomp4.Stbl{}) // <stbl>
	if err != nil {
		return err
	}

	_, err = w.writeBoxStart(&gomp4.Stsd{ // <stsd>
		EntryCount: 1,
	})
	if err != nil {
		return err
	}

	switch ttrack := track.Format.(type) {
	case *format.H264:
		_, err = w.writeBoxStart(&gomp4.VisualSampleEntry{ // <avc1>
			SampleEntry: gomp4.SampleEntry{
				AnyTypeBox: gomp4.AnyTypeBox{
					Type: gomp4.BoxTypeAvc1(),
				},
				DataReferenceIndex: 1,
			},
			Width:           uint16(width),
			Height:          uint16(height),
			Horizresolution: 4718592,
			Vertresolution:  4718592,
			FrameCount:      1,
			Depth:           24,
			PreDefined3:     -1,
		})
		if err != nil {
			return err
		}

		_, err = w.WriteBox(&gomp4.AVCDecoderConfiguration{ // <avcc/>
			AnyTypeBox: gomp4.AnyTypeBox{
				Type: gomp4.BoxTypeAvcC(),
			},
			ConfigurationVersion:       1,
			Profile:                    spsp.ProfileIdc,
			ProfileCompatibility:       sps[2],
			Level:                      spsp.LevelIdc,
			LengthSizeMinusOne:         3,
			NumOfSequenceParameterSets: 1,
			SequenceParameterSets: []gomp4.AVCParameterSet{
				{
					Length:  uint16(len(sps)),
					NALUnit: sps,
				},
			},
			NumOfPictureParameterSets: 1,
			PictureParameterSets: []gomp4.AVCParameterSet{
				{
					Length:  uint16(len(pps)),
					NALUnit: pps,
				},
			},
		})
		if err != nil {
			return err
		}

		_, err = w.WriteBox(&gomp4.Btrt{ // <btrt/>
			MaxBitrate: 1000000,
			AvgBitrate: 1000000,
		})
		if err != nil {
			return err
		}

		err = w.writeBoxEnd() // </avc1>
		if err != nil {
			return err
		}

	case *format.MPEG4Audio:
		_, err = w.writeBoxStart(&gomp4.AudioSampleEntry{ // <mp4a>
			SampleEntry: gomp4.SampleEntry{
				AnyTypeBox: gomp4.AnyTypeBox{
					Type: gomp4.BoxTypeMp4a(),
				},
				DataReferenceIndex: 1,
			},
			ChannelCount: uint16(ttrack.Config.ChannelCount),
			SampleSize:   16,
			SampleRate:   uint32(ttrack.ClockRate() * 65536),
		})
		if err != nil {
			return err
		}

		enc, _ := ttrack.Config.Marshal()

		_, err = w.WriteBox(&gomp4.Esds{ // <esds/>
			FullBox: gomp4.FullBox{
				Version: 0,
				Flags:   [3]byte{0x00, 0x00, 0x00},
			},
			Descriptors: []gomp4.Descriptor{
				{
					Tag:  gomp4.ESDescrTag,
					Size: 32 + uint32(len(enc)),
					ESDescriptor: &gomp4.ESDescriptor{
						ESID: uint16(track.ID),
					},
				},
				{
					Tag:  gomp4.DecoderConfigDescrTag,
					Size: 18 + uint32(len(enc)),
					DecoderConfigDescriptor: &gomp4.DecoderConfigDescriptor{
						ObjectTypeIndication: 0x40,
						StreamType:           0x05,
						UpStream:             false,
						Reserved:             true,
						MaxBitrate:           128825,
						AvgBitrate:           128825,
					},
				},
				{
					Tag:  gomp4.DecSpecificInfoTag,
					Size: uint32(len(enc)),
					Data: enc,
				},
				{
					Tag:  gomp4.SLConfigDescrTag,
					Size: 1,
					Data: []byte{0x02},
				},
			},
		})
		if err != nil {
			return err
		}

		_, err = w.WriteBox(&gomp4.Btrt{ // <btrt/>
			MaxBitrate: 128825,
			AvgBitrate: 128825,
		})
		if err != nil {
			return err
		}

		err = w.writeBoxEnd() // </mp4a>
		if err != nil {
			return err
		}
	}

	err = w.writeBoxEnd() // </stsd>
	if err != nil {
		return err
	}

	_, err = w.WriteBox(&gomp4.Stts{ // <stts>
	})
	if err != nil {
		return err
	}

	_, err = w.WriteBox(&gomp4.Stsc{ // <stsc>
	})
	if err != nil {
		return err
	}

	_, err = w.WriteBox(&gomp4.Stsz{ // <stsz>
	})
	if err != nil {
		return err
	}

	_, err = w.WriteBox(&gomp4.Stco{ // <stco>
	})
	if err != nil {
		return err
	}

	err = w.writeBoxEnd() // </stbl>
	if err != nil {
		return err
	}

	err = w.writeBoxEnd() // </minf>
	if err != nil {
		return err
	}

	err = w.writeBoxEnd() // </mdia>
	if err != nil {
		return err
	}

	err = w.writeBoxEnd() // </trak>
	if err != nil {
		return err
	}

	return nil
}