From 7447699735fec86bc90682d02507ce0a18a47fda Mon Sep 17 00:00:00 2001
From: Muaz Ahmad <mahmad2000@protonmail.com>
Date: Wed, 23 Aug 2023 22:47:15 +0500
Subject: [PATCH] parsing upto avc1 and mp4a boxes

---
 mp4-tree.js | 46 ++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 40 insertions(+), 6 deletions(-)

diff --git a/mp4-tree.js b/mp4-tree.js
index 61b3089..aec4acf 100644
--- a/mp4-tree.js
+++ b/mp4-tree.js
@@ -17,8 +17,38 @@ class MP4Tree {
 	}
 
 	parse_codecs() {
-		this.parse_until('moov');
-		console.log(this.idx);
+		this.parse_into('moov', 8);
+		while (this.idx < this.data.byteLength) {
+			if (!this.parse_until('trak')) {
+				break;
+			}
+			const curr_track_end = this.idx + this.read_next_head().len;
+			this.idx += 8
+			this.parse_into('mdia', 8);
+			this.parse_into('minf', 8);
+			const track_type_head = this.read_next_head().name;
+			if (track_type_head == 'smhd' || track_type_head == 'vmhd') {
+				this.parse_into('stbl', 8);
+				this.parse_into('stsd', 16);
+				const media_sample = this.read_next_head().name;
+				if (media_sample == 'avc1') {
+					this.parse_avc1();
+				} else if (media_sample == 'mp4a') {
+					this.parse_mp4a();
+				}
+			}
+			this.idx = curr_track_end;
+		}
+	}
+	
+	parse_avc1() {
+		this.parse_into('avc1', 86);
+		console.log(this.read_next_head());
+	}
+
+	parse_mp4a() {
+		this.parse_into('mp4a', 36);
+		console.log(this.read_next_head());
 	}
 
 	get_mime() {
@@ -29,21 +59,25 @@ class MP4Tree {
 		return this.codecs.join(', ');
 	}
 
+	parse_into(name, header_offset) {
+		this.parse_until(name);
+		this.idx += header_offset;
+	}
+
 	parse_until(name) {
 		let curr_head = null;
-		while (this.idx < this.data.byteLength) {
+		while (this.idx + 8 < this.data.byteLength) {
 			curr_head = this.read_next_head();
-			console.log(curr_head);
 			if (curr_head.name == name) {
-				break;
+				return true;
 			} else {
 				this.idx += curr_head.len;
 			}
 		}
+		return false;
 	}
 	
 	read_next_head() {
 		return {"len": this.data.getUint32(this.idx), "name": this.data.getString(this.idx + 4, 4)};
 	}
 }
-