Cannot read property 'formats' of undefined when I try to downloadFromInfo() about node-ytdl-core

[fent]

ytld.getInfo() is NOT synchronous, it needs to travel to youtube servers to get video info.

ytdl.getInfo('https://www.youtube.com/watch?v=rHLbd3nvu88', { downloadURL: true }, function(err, songInfo) {
  if (err) throw err;
  ytdl.downloadFromInfo(songInfo, { filter: 'audioonly' }).pipe(res);
});

ytdl() is synchronous because it returns a readable stream, but its data isn't immediately available.

[johnRivs]

I see.. My knowledge on node is crippling me at the moment. This is what I'm ultimately trying:

var app      = require('express')(),
    ytdl     = require('ytdl-core'),
    ffmpeg   = require('fluent-ffmpeg'),
    archiver = require('archiver'),
    async    = require('async');

app.get('/', function(req, res) {
    var archive = archiver.create('zip', {});

    ytdl.getInfo('https://www.youtube.com/watch?v=rHLbd3nvu88', { downloadURL: true }, function(err, songInfo) {
        archive.append(
            ffmpeg(
                ytdl('https://www.youtube.com/watch?v=rHLbd3nvu88', { filter: 'audioonly' })
            ).format('mp3').pipe(), {
                name: Date.now() + '.mp3'
            }
        );
    });

    res.setHeader('Content-disposition', 'attachment; filename=u2fy_' + Date.now() + '.zip');
    res.setHeader('Content-type', 'application/zip');

    archive.finalize().pipe(res);
});

When I do this without getInfo(), it works perfectly; the user recieves a zip file with the audio without it being created on the server. However, when I perform the same thing inside the callback function, I get an error by archiver: append: queue closed. Passing songInfo to ytdl() doesn't seem to work for me either.

Any hint?

[fent]

That sounds like it might be an error with ytdl, but why do you need to call ytdl.getInfo() if you're not using songInfo?

You could also listen for the info event on the stream it returns.

var video = ytdl('https://www.youtube.com/watch?v=rHLbd3nvu88', { filter: 'audioonly' });
video.on('info', function() {
});

[johnRivs]

I couldn't get that work, because of said [Error: append: queue closed] from archiver. Switched to:

ffmpeg(
    ytdl.downloadFromInfo(songInfo, { filter: 'audioonly' })
)

Same thing though.

About the info event, would that work in my case? Because I need to pass a stream to ffmpeg(). How would that look like if I was to use the info event callback?

[fent]

do you need the info?

[johnRivs]

Oh I forgot, I used Date.now() instead of the actual thing I'm supposed to use, which is the title of the video. Sorry about that confusion :P

[fent]

Oh, then something like

var video = ytdl('https://www.youtube.com/watch?v=rHLbd3nvu88', { filter: 'audioonly' });
video.on('info', function(info) {
  archive.append(ffmpeg(video).format('mp3').pipe(), { name: info.title});
});

[johnRivs]

No luck :( Seems like archive.append() doesn't like being inside a callback.

[johnRivs]

Ok, I've gone a different direction. My guess is, archive.finalize() gets piped to the response way to early, the queue closes and no more appends can happen.

So now I'm returning the archive but only finalizing it when everything is in:

var archive = archiver.create('zip', {}),
    songs   = [
        'https://www.youtube.com/watch?v=vK_3AS2gavY'
    ],
    entries = 0;

var video = ytdl(songs[0], { filter: 'audioonly' });

video.on('info', function(info) {
    archive.append(ffmpeg(video).format('mp3').pipe(), { name: info.title + '.mp3'});
});

archive.on('entry', function(data) {
    entries++;

    if (songs.length === entries) {
        archive.finalize();
    }
});

res.setHeader('Content-disposition', 'attachment; filename=u2fy_' + Date.now() + '.zip');
res.setHeader('Content-type', 'application/zip');

archive.pipe(res);

It works, however, I can't figure out a way to make a loop in order to download more than 1 video. If I was able to apply the listener to ytdl instead of a specific var video = ytdl(songs[0], { filter: 'audioonly' });, I wouldn't have this problem I guess. Or if ytdl accepted an array of URLs so the info event can be triggered more than once.

By the way, the entry event gets triggered once an entry has been processed.

[fent]

I don't understand why this wouldn't work for more than 1 video.

wouldn't you just loop for the list of video urls and append for each?