How to read metadata from mp4 using mp4.js node module?

Question

I am trying to read the metadata tags from an mp4 file into my javascript using the node module mp4js. I followed the model provided on that page but with some issue.

I tried the following:

var mp4 = require('mp4js');

mp4({ file: 'small.mp4', type: 'local' }, function (err, tags) {
    // tags now contains your MP4 tags
    console.log('Tags: ' + tags)
    $scope.mp4Tags = tags;
});

and I was met with Uncaught TypeError: Cannot read property 'join' of undefined

Does anyone know what I'm missing here? Could it be that the mp4 doesn't have any tags? I just googled "sample mp4" and downloaded something. It's my first time trying this module and I am pretty new to node.

I'm also open to other suggestions for reading mp4 metadata.

Thank you very much for your time and let me know if you need any additional from me.

EDIT 8.26.2015

Following Brad's suggestion, I tried the following code to read metadata from an mp4:

    var child_process = require('child_process');
ls = child_process.spawn('ffmpeg/bin/ffprobe.exe', ['-print_format', 'json', 'out.mp4']);

ls.stdout.on('data', function (data) {
    console.log('stdout: ' + data);
    $scope.mp4data = data;
});

I created mp4.out by following this example for adding a title meta tag using ffmpeg from the command line. Here is a screenshot of my output. Here is the command I entered:

ffmpeg -i in.avi -metadata title="my title" out.flv

After running my app with the code above, the value stored in $scope.mp4data is a Native Buffer that looks like this. All I see are some numbers, but no metadata tags. How can I view the metadata such as the title that I set using the command above? Am I missing something in the arguments? Or maybe I should be looking at something other than data?

Thanks for the help. I may just post this as a new question since the focus has shifted.

EDIT: Solution

Here's where I landed thanks to Brad's help:

$scope.mp4data = "";
ls.stdout.on('data', function (data) {
    $scope.mp4data = $scope.mp4data + data.toString();
});

ls.stdout.on('end', function (data) {
    $scope.mp4data = JSON.parse($scope.mp4data);
});

works great for reading metadata from my mp4! Thanks Brad!

Answer 1

I recommend using FFprobe (from the FFmpeg project) to do this instead. It supports many containers, including MP4.

You can use ffprobe -print_format json to have it output JSON data that you can parse inside your Node.js app.

Some examples here: https://stackoverflow.com/a/8191228/362536