new track box and track header box implementation

Box.go

@@ -28,6 +28,10 @@ const (
 	BoxTypeMovie = "moov"
 	// BoxTypeMovieHeader Movie Header Box
 	BoxTypeMovieHeader = "mvhd"
+	// BoxTypeTrackBox Track Box
+	BoxTypeTrackBox = "trak"
+	// BoxTypeTrackHeaderBox Track Header Box
+	BoxTypeTrackHeaderBox = "tkhd"
 	// BoxTypeMovieFragment Movie Fragment Box
 	BoxTypeMovieFragment = "moof"
 	// BoxTypeMovieFragmentHeader Movie Fragment Header Box

Parser.go

@@ -112,6 +112,10 @@ func parseNextBox(reader io.Reader, filePosition uint64) (box interface{}, endPo
 		box, err = ParseMovieBox(filePosition, boxHeaderSize, boxContentBytes)
 	case BoxTypeMovieHeader:
 		box = ParseMovieHeaderBox(filePosition, boxHeaderSize, boxContentBytes)
+	case BoxTypeTrackBox:
+		box, err = ParseTrackBox(filePosition, boxHeaderSize, boxContentBytes)
+	case BoxTypeTrackHeaderBox:
+		box = ParseTrackHeaderBox(filePosition, boxHeaderSize, boxContentBytes)
 	case BoxTypeMovieFragment:
 		box, err = ParseMovieFragmentBox(filePosition, boxHeaderSize, boxContentBytes)
 	case BoxTypeMovieFragmentHeader:

README.md

@@ -23,8 +23,8 @@ Implementation progress
 | 8.1.3 Progressive Download Information Box         | pdin           |      - |
 | 8.2.1 Movie Box                                    | moov           |   100% |
 | 8.2.2 Movie Header Box                             | mvhd           |   100% |
-| 8.3.1 Track Box                                    | trak           |      - |
+| 8.3.1 Track Box                                    | trak           |   100% |
-| 8.3.2 Track Header Box                             | tkhd           |      - |
+| 8.3.2 Track Header Box                             | tkhd           |   100% |
 | 8.3.3 Track Reference Box                          | tref           |      - |
 | 8.3.4 Track Group Box                              | trgr           |      - |
 | 8.4.1 Media Box                                    | mdia           |      - |

TrackBox.go

@@ -0,0 +1,48 @@
+// Copyright 2024 Martin Riedl
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package gomp4
+
+// TrackBox track box struct
+//
+// 8.3.1 Track Box
+// Box Type: ‘trak’
+// Container: Movie Box (‘moov’)
+// Mandatory: Yes
+// Quantity: One or more
+//
+// This is a container box for a single track of a presentation. A presentation consists of one or more tracks.
+// Each track is independent of the other tracks in the presentation and carries its own temporal and
+// spatial information. Each track will contain its associated Media Box.
+//
+// Tracks are used for two purposes: (a) to contain media data (media tracks) and (b) to contain
+// packetization information for streaming protocols (hint tracks).
+//
+// There shall be at least one media track within an ISO file, and all the media tracks that contributed to
+// the hint tracks shall remain in the file, even if the media data within them is not referenced by the hint
+// tracks; after deleting all hint tracks, the entire un‐hinted presentation shall remain.
+type TrackBox struct {
+	*Box
+	ChildBoxes []interface{}
+}
+
+// ParseTrackBox creates a new track box struct based on bytes
+func ParseTrackBox(filePosition uint64, headerSize uint32, content []byte) (*TrackBox, error) {
+	box := &TrackBox{Box: &Box{filePosition, headerSize}}
+
+	// parse child boxes
+	var err error
+	box.ChildBoxes, err = box.parseChildBoxes(filePosition, content)
+	return box, err
+}

TrackHeaderBox.go

@@ -0,0 +1,194 @@
+// Copyright 2024 Martin Riedl
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package gomp4
+
+import (
+	"encoding/binary"
+	"time"
+)
+
+// TrackHeaderBox track header box struct
+//
+// 8.3.2 Track Header Box
+//
+// Box Type: ‘tkhd’
+// Container: Track Box (‘trak’)
+// Mandatory: Yes
+// Quantity: Exactly one
+//
+// This box specifies the characteristics of a single track. Exactly one Track Header Box is contained in a
+// track.
+//
+// In the absence of an edit list, the presentation of a track starts at the beginning of the overall
+// presentation. An empty edit is used to offset the start time of a track.
+//
+// The default value of the track header flags for media tracks is 7 (track_enabled, track_in_movie,
+// track_in_preview). If in a presentation all tracks have neither track_in_movie nor track_in_preview set,
+// then all tracks shall be treated as if both flags were set on all tracks. Server hint tracks should have the
+// track_in_movie and track_in_preview set to 0, so that they are ignored for local playback and
+// preview.
+//
+// Under the ‘iso3’ brand or brands that share its requirements, the width and height in the track header
+// are measured on a notional 'square' (uniform) grid. Track video data is normalized to these dimensions
+// (logically) before any transformation or placement caused by a layup or composition system. Track
+// (and movie) matrices, if used, also operate in this uniformly‐scaled space.
+//
+// The duration field here does not include the duration of following movie fragments, if any, but only of
+// the media in the enclosing Movie Box. The Movie Extends Header box may be used to document the
+// duration including movie fragments, when desired and possible.
+type TrackHeaderBox struct {
+	*FullBox
+	// is an integer that declares the creation time of this track (in seconds since
+	// midnight, Jan. 1, 1904, in UTC time).
+	CreationTimeV0 time.Time
+	// is an integer that declares the creation time of this track (in seconds since
+	// midnight, Jan. 1, 1904, in UTC time).
+	CreationTimeV1 time.Time
+	// is an integer that declares the most recent time the track was modified (in
+	// seconds since midnight, Jan. 1, 1904, in UTC time).
+	ModificationTimeV0 time.Time
+	// is an integer that declares the most recent time the track was modified (in
+	// seconds since midnight, Jan. 1, 1904, in UTC time).
+	ModificationTimeV1 time.Time
+	// is an integer that uniquely identifies this track over the entire life‐time of this
+	// presentation. Track IDs are never re‐used and cannot be zero.
+	TrackID uint32
+	// is an integer that indicates the duration of this track (in the timescale indicated in the
+	// Movie Header Box). The value of this field is equal to the sum of the durations of all of the track’s
+	// edits. If there is no edit list, then the duration is the sum of the sample durations, converted into
+	// the timescale in the Movie Header Box. If the duration of this track cannot be determined then
+	// duration is set to all 1s.
+	DurationV0 uint32
+	// is an integer that indicates the duration of this track (in the timescale indicated in the
+	// Movie Header Box). The value of this field is equal to the sum of the durations of all of the track’s
+	// edits. If there is no edit list, then the duration is the sum of the sample durations, converted into
+	// the timescale in the Movie Header Box. If the duration of this track cannot be determined then
+	// duration is set to all 1s.
+	DurationV1 uint64
+	// specifies the front‐to‐back ordering of video tracks; tracks with lower numbers are closer
+	// to the viewer. 0 is the normal value, and ‐1 would be in front of track 0, and so on.
+	Layer int16
+	// is an integer that specifies a group or collection of tracks. If this field is 0
+	// there is no information on possible relations to other tracks. If this field is not 0, it should be the
+	// same for tracks that contain alternate data for one another and different for tracks belonging to
+	// different such groups. Only one track within an alternate group should be played or streamed at
+	// any one time, and must be distinguishable from other tracks in the group via attributes such as
+	// bitrate, codec, language, packet size etc. A group may have only one member.
+	AlternativeGroup int16
+	// is a fixed 8.8 value specifying the track's relative audio volume. Full volume is 1.0
+	// (0x0100) and is the normal value. Its value is irrelevant for a purely visual track. Tracks may be
+	// composed by combining them according to their volume, and then using the overall Movie
+	// Header Box volume setting; or more complex audio composition (e.g. MPEG‐4 BIFS) may be
+	// used.
+	Volume Fixed88
+	// provides a transformation matrix for the video; (u,v,w) are restricted here to (0,0,1), hex
+	// (0,0,0x40000000).
+	Matrix []int32
+	// fixed‐point 16.16 values are track‐dependent as follows:
+	//
+	// For text and subtitle tracks, they may, depending on the coding format, describe the suggested
+	// size of the rendering area. For such tracks, the value 0x0 may also be used to indicate that the
+	// data may be rendered at any size, that no preferred size has been indicated and that the actual
+	// size may be determined by the external context or by reusing the width and height of another
+	// track. For those tracks, the flag track_size_is_aspect_ratio may also be used.
+	// For non‐visual tracks (e.g. audio), they should be set to zero.
+	// For all other tracks, they specify the track's visual presentation size. These need not be the same
+	// as the pixel dimensions of the images, which is documented in the sample description(s); all
+	// images in the sequence are scaled to this size, before any overall transformation of the track
+	// represented by the matrix. The pixel dimensions of the images are the default values.
+	Width Fixed1616
+	// fixed‐point 16.16 values are track‐dependent as follows:
+	//
+	// For text and subtitle tracks, they may, depending on the coding format, describe the suggested
+	// size of the rendering area. For such tracks, the value 0x0 may also be used to indicate that the
+	// data may be rendered at any size, that no preferred size has been indicated and that the actual
+	// size may be determined by the external context or by reusing the width and height of another
+	// track. For those tracks, the flag track_size_is_aspect_ratio may also be used.
+	// For non‐visual tracks (e.g. audio), they should be set to zero.
+	// For all other tracks, they specify the track's visual presentation size. These need not be the same
+	// as the pixel dimensions of the images, which is documented in the sample description(s); all
+	// images in the sequence are scaled to this size, before any overall transformation of the track
+	// represented by the matrix. The pixel dimensions of the images are the default values.
+	Height Fixed1616
+}
+
+const (
+	// TrackHeaderBoxFlagTrackEnabled Track Enabled Flag
+	// Indicates that the track is enabled. Flag value is 0x000001. A disabled track (the
+	// low bit is zero) is treated as if it were not present.
+	TrackHeaderBoxFlagTrackEnabled uint32 = 0x00000001
+
+	// TrackHeaderBoxFlagTrackInMovie Track in Movie
+	// Indicates that the track is used in the presentation. Flag value is 0x000002.
+	TrackHeaderBoxFlagTrackInMovie uint32 = 0x00000002
+
+	// TrackHeaderBoxFlagTrackInPreview Track in Preview
+	// Indicates that the track is used when previewing the presentation. Flag value
+	// is 0x000004.
+	TrackHeaderBoxFlagTrackInPreview uint32 = 0x00000004
+
+	// TrackHeaderBoxFlagTrackSizeIsAspectRatio Track Size is Aspect Ratio
+	// Indicates that the width and height fields are not expressed in
+	// pixel units. The values have the same units but these units are not specified. The values are
+	// only an indication of the desired aspect ratio. If the aspect ratios of this track and other
+	// related tracks are not identical, then the respective positioning of the tracks is undefined,
+	// possibly defined by external contexts. Flag value is 0x000008.
+	TrackHeaderBoxFlagTrackSizeIsAspectRatio uint32 = 0x00000008
+)
+
+// ParseTrackHeaderBox creates a new Track Header Box struct
+func ParseTrackHeaderBox(filePosition uint64, headerSize uint32, content []byte) *TrackHeaderBox {
+	box := &TrackHeaderBox{
+		FullBox: newFullBox(&Box{filePosition, headerSize}, content[0:4]),
+	}
+
+	position := 4
+	if box.Version == 1 {
+		box.CreationTimeV1 = since1904ToTime(int64(binary.BigEndian.Uint64(content[4:12])))
+		box.ModificationTimeV1 = since1904ToTime(int64(binary.BigEndian.Uint64(content[12:20])))
+		box.TrackID = binary.BigEndian.Uint32(content[20:24])
+		// uint32 reserved
+		box.DurationV1 = binary.BigEndian.Uint64(content[28:36])
+		position += 32
+	} else { // version == 0
+		box.CreationTimeV0 = since1904ToTime(int64(binary.BigEndian.Uint32(content[4:8])))
+		box.ModificationTimeV0 = since1904ToTime(int64(binary.BigEndian.Uint32(content[8:12])))
+		box.TrackID = binary.BigEndian.Uint32(content[12:16])
+		// uint32 reserved
+		box.DurationV0 = binary.BigEndian.Uint32(content[20:24])
+		position += 20
+	}
+
+	// skip 2 reserved uint32
+	position += 4 + 4
+
+	// parse next fields
+	box.Layer = int16(binary.BigEndian.Uint16(content[position : position+2]))
+	box.AlternativeGroup = int16(binary.BigEndian.Uint16(content[position+2 : position+4]))
+	box.Volume = NewFixed88ByBytes(content[position+4 : position+6])
+	position += 2 + 2 + 2 + 2 // 4 bytes for layer, 2 bytes for alternative group, 2 bytes for volume and 2 bytes reserved
+
+	// parse matrix
+	for i := 0; i < 9; i++ {
+		box.Matrix = append(box.Matrix, int32(binary.BigEndian.Uint32(content[position:position+4])))
+		position += 4
+	}
+
+	// parse width/height
+	box.Width = NewFixed1616ByBytes(content[position : position+4])
+	box.Height = NewFixed1616ByBytes(content[position+4 : position+8])
+
+	return box
+}