How to Create High Quality Ambisonic Deliverables for YouTube VR
When producing 360 video content, we really want to maximize not only our picture quality, but also sound quality. Spatial audio is possibly the most frustrating aspect about delivering premium level 360 video experiences because of the plethora of formats, the incompatibilities between players and platforms, and the challenges of monitoring the final mix. This post hopes the help change that by showing you how we deliver the best quality sounding YouTube material.
Before you do anything, make sure you receive the proper deliverables from your post production sound team. If you aren’t working with a post production sound team, think about working with someone in the future. The fact is that 90% of the sounds you hear on broadcast television and in feature films are recorded after production wraps. So if you want to have truly high quality sound, you need high quality people to work on it. I’ve found that traditional 2D sound designers have had a lot of fun working in 360 space as it provides some new challenges and some new creative opportunities to play with sound.
The two major sound plug in packages are the Facebook 360 Spatial Workstation (available for FREE) and the public beta of the Dolby Atmos tools (often available when working with a post production sound studio such as Margarita Mix, Empty Sea Audio, etc). These are important tools that allow the sound designer and re-recording mixer to place “objects” in 360 space. The details of these tools are for another post, but what you’ll want to make sure you receive as deliverables are:
- .atmos file (if working with Dolby Atmos)
- 8-Channel FB360 file — with all head trackable elements
- 2-Channel Head Locked file — all elements that should stay locked in space, such as voiceover, music, BG elements
- 8-Channel .wav with all elements — used to create a YouTube AmbiX mixdown
- YouTube AmbiX file as a 4 channel 16bit PCM Wav — to these specifications
- .tbe file
- Quad-binaural files — used for SamsungVR (to be covered in another post!).
If you have the 8-Channel files, you can create most of these using the FB360 Encoder, but I think it’s best to ask your sound team to deliver what you want. You can even use the FB360 encoder to create YouTube ready files, but I found that the sound quality was not as good as if I had done it by hand, so I recommend you follow the steps below for the best final product.
So now that we’ve gotten some background out of the way, here is how to marry the audio to the picture and create the highest quality spatial audio mix for YouTube.
- Open iFFMPEG and drag your .mp4 in.
Quick tip: YouTube will accept huge frame sizes and use all that extra information to make your image look better. So feel free to upload that 8K x 8K stereoscopic file! Just makes sure you don’t go over their upload space restrictions.
2. Select the container as .mov
3. On the right, change the h.264 container to “Pass Thru”
4. Delete the audio channel
5. Add a new audio channel and click “Edit”
6. Add External file and select your YouTube AmbiX file.
7. Set the encoding to PCM16LE
8. Set the channels to 4.0
9. Hit play to process the files. This should be very quick.
10. Open up the Spatial Media Metadata Injector
11. Open the video file that iFFMPEG created. Select the appropriate checkboxes of metadata to inject and click Save.
And there you have it. You should have a file ready to upload to YouTube. Keeping the audio as PCM maintains the very highest quality and sounds great. I recommend uploading it privately and waiting until the Spatial Audio kicks in to check it. Alternatively, if you have an Android phone, you can download the Jump Inspector and check your work there.
Pro tip: As of this writing, Jump Inspector will stop playing back your video if the audio is shorter than the video, so be sure they match!
We’ve found this method to be the best way to ensure the audio is high quality when processed by YouTube. Remember, to check on YouTube using Chrome as your web browser. Now go forth and make spatial audio an important part of your 360 video content creation!
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