Hello Class English Grammar section videos have no audio

I’ve just downloaded the Hello Class English channel. The vocabulary and conversational videos work fine. The grammar videos have no audio. I deleted and reinstalled, but no change. Maybe someone should check that?

Thanks for reporting this!

While the audio for both the vocabulary and grammar videos play fine for me using Chrome on OS X, I checked into this further and noticed that the YouTube videos for the two topics use different audio encodings. The vocabulary videos use aac, while the grammar videos use mp3, so there may be issues with playing mp3 audio on your device. Could you let me know what OS and browser are you using to view the content?

The audio doesn’t work on the iPad2s we are using with any of the browsers: Firefox, Chrome, etc. It does work on Chrome on Mac OS X. It doesn’t work on Firefox, nor Safari on Mac OS X. Strange as MP3 is some a common format. Wonder what the problem is!?!

We did some more checking, and it looks like while Safari supports mp3 audio files, for some reason it does not support mp3 audio in mp4 videos. Firefox does not internally support this, but will use a third-party decoder if available, which is probably why it also does not work on OS X. On iPad, all browsers, including Firefox and Chrome, actually use Apple’s browser internally, so that’s why no browsers will support it there. Here’s a link from Mozilla that has more detail:

So it looks like what we’ll need to do is to convert the video files after we download them to use a more compatible audio format. Thanks again for bringing this to our attention! We’ll work on getting an updated version of the channel that no longer uses the mp3 format for the audio!

Thanks for your research. Will you, then, do the download/conversion and then repost to the channel?

Your research uncovered an answer to another issue we are facing with the iPad2s and KA Lite. Using different browsers on iOS doesn’t resolve some issues there. The fact that all browsers make use of Apple’s browsers internally narrows the culprit of the problems to one place! At least that’s what I’m thinking.

Yes, we have already started work on the update! We’ll post an update here when the updated channel is ready.

@cjackson Okay, we’ve updated the channel! Could you try importing it again and see if the grammar videos play for you now on the iPads?