Fix to generate valid .mp4 from ADTS stream

[gmcgarry]

Here's a simple nodejs module to convert .aac to .mp4

import muxjs from "./es/index.js"
import * as fs from 'fs'

const transmuxer = new muxjs.mp4.Transmuxer({ })

const readable = fs.createReadStream('sample.aac')
readable.on('data', (chunk) => transmuxer.push(chunk))
readable.on('end', () => transmuxer.flush())

const writable = fs.createWriteStream('output.mp4')

let isFirst = true

transmuxer.on('data', (segment) => {
    if (isFirst) {
        const data = new Uint8Array(segment.initSegment.byteLength + segment.data.byteLength)
        data.set(segment.initSegment, 0)
        data.set(segment.data, segment.initSegment.byteLength)
        writable.write(data)
    } else {
        writable.write(segment.data)
    }
    isFirst = false
})

Here's the patch to get it working so that the output file is playable:

diff --git a/lib/mp4/mp4-generator.js b/lib/mp4/mp4-generator.js
index a44781a..5ac031d 100644
--- a/lib/mp4/mp4-generator.js
+++ b/lib/mp4/mp4-generator.js
@@ -305,7 +305,7 @@ moov = function(tracks) {
     boxes[i] = trak(tracks[i]);
   }
 
-  return box.apply(null, [types.moov, mvhd(0xffffffff)].concat(boxes).concat(mvex(tracks)));
+  return box.apply(null, [types.moov, mvhd(0)].concat(boxes).concat(mvex(tracks)));
 };
 mvex = function(tracks) {
   var
@@ -637,7 +637,7 @@ traf = function(track) {
  * @return {Uint8Array} the track box
  */
 trak = function(track) {
-  track.duration = track.duration || 0xffffffff;
+  track.duration = track.duration
   return box(types.trak,
              tkhd(track),
              mdia(track));
diff --git a/lib/mp4/transmuxer.js b/lib/mp4/transmuxer.js
index a248585..8f709d6 100644
--- a/lib/mp4/transmuxer.js
+++ b/lib/mp4/transmuxer.js
@@ -962,6 +962,7 @@ Transmuxer = function(options) {
       }
 
       audioTrack = audioTrack || {
+        id: 1,
         timelineStartInfo: {
           baseMediaDecodeTime: self.baseMediaDecodeTime
         },