From 0eedf34735e50272208c7b693e0146562d4eed66 Mon Sep 17 00:00:00 2001
From: Martin Riedl <martin.riedl.92@googlemail.com>
Date: Tue, 3 Dec 2024 19:29:14 +0100
Subject: [PATCH] new sample entry implementation for avc1

---
 README.md               |  7 +++++--
 SampleDescriptionBox.go | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 1c9109c..7018331 100644
--- a/README.md
+++ b/README.md
@@ -1,10 +1,12 @@
 # goMP4
+
 [![pipeline status](https://gitlab.com/martinr92/gomp4/badges/main/pipeline.svg)](https://gitlab.com/martinr92/gomp4/commits/main)
 [![coverage report](https://gitlab.com/martinr92/gomp4/badges/main/coverage.svg)](https://gitlab.com/martinr92/gomp4/commits/main)
 
 mp4 implementation in golang based on spec ISO ICE 14496-12:2015
 
 ## Parser
+
 ```go
 parser := gomp4.NewParser(file)
 if err := parser.Parse(); err != nil {
@@ -13,7 +15,8 @@ if err := parser.Parse(); err != nil {
 ```
 
 ## Progress
-Implementation progress
+
+Implementation progress of ISO ICE 14496-12:2015:
 
 | Chapter                                            | Box Types      | Parser |
 |----------------------------------------------------|----------------|-------:|
@@ -34,7 +37,7 @@ Implementation progress
 | 8.4.5.2 Null Media Header Box                      | nmhd           |      - |
 | 8.4.6 Extended language tag                        | elng           |      - |
 | 8.5.1 Sample Table Box                             | stbl           |   100% |
-| 8.5.2 Sample Description Box                       | stsd           |    20% |
+| 8.5.2 Sample Description Box                       | stsd           |   100% |
 | 8.5.3 Degradation Priority Box                     | stdp           |      - |
 | 8.6.1.2 Decoding Time to Sample Box                | stts           |      - |
 | 8.6.1.3 Composition Time to Sample Box             | ctts           |      - |
diff --git a/SampleDescriptionBox.go b/SampleDescriptionBox.go
index 90c6687..e061d7c 100644
--- a/SampleDescriptionBox.go
+++ b/SampleDescriptionBox.go
@@ -89,5 +89,40 @@ func ParseSampleDescriptionBox(parser *Parser, filePosition uint64, headerSize u
 	// entry counter
 	box.EntryCount = binary.BigEndian.Uint32(content[4:8])
 
+	// parse child boxes
+	var err error
+	box.ChildBoxes, err = box.parseChildBoxes(parser, BoxTypeSampleDescription, filePosition, content[8:])
+	if err != nil {
+		return box, err
+	}
+
+	// validate entry count
+	if int(box.EntryCount) != len(box.ChildBoxes) {
+		return box, fmt.Errorf("invalid amount of boxes at %d; found %d but expected %d", filePosition, len(box.ChildBoxes), box.EntryCount)
+	}
+
+	return box, nil
+}
+
+type SampleEntry struct {
+	*Box
+	// is an integer that contains the index of the data reference to use to
+	// retrieve data associated with samples that use this sample description. Data references are
+	// stored in Data Reference Boxes. The index ranges from 1 to the number of data references.
+	DataReferenceIndex uint16
+}
+
+func ParseSampleEntry(filePosition uint64, headerSize uint32, content []byte) *SampleEntry {
+	box := &SampleEntry{
+		Box: &Box{filePosition, headerSize},
+	}
+
+	// skip reserved
+	position := 2 * 8
+
+	// parse reference index
+	box.DataReferenceIndex = binary.BigEndian.Uint16(content[position : position+2])
+	log.Println("data reference index", box.DataReferenceIndex) // TODO: remove me
+
 	return box
 }