… for Codecs & Media

Tip #455: Audio Compression Settings for YouTube

YouTube always recompresses media, so send it a larger-than-normal file.

Audio compression settings for a stereo MP3 file for YouTube.

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Last week, in Tip #451, I presented compression settings for audio you were posting for a podcast. YouTube and other social media settings are different, however. Here’s what you need to know.

YouTube, and other social media services, always recompress your data. This is necessary to support all the different playback devices, software and codecs in the real world.

If you send YouTube a perfectly compressed file, it will still recompress it – because it has to convert it to all these different codecs. In doing so, because there is not enough data, it will damage the quality of your audio.

To prevent this, we need to create a “mezzanine,” or middle, compression file so that when YouTube recompresses the file it has some bits it can throw away. MP3 is an excellent choice for audio-only files. AAC, which is part of H.264 compression, is a good choice when you are compressing audio with video.

Here are the settings:

Setting Mono Stereo
Codec for audio-only MP3 MP3
Codec for audio with video AAC AAC
Sample rate for audio-only 44.1 KHz 44.1k Khz
Sample rate for audio with video 48 KHz 48 Khz
Bit-depth 16-bits 16-bits
Data rate 160 kbps 320 kbps

EXTRA CREDIT

Tip #458 explains video compression settings for YouTube


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… for Random Weirdness

Tip #442: Find the Funny

Funny takes work.

(Image courtesy of Pexels.com.)

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This article, written by Jourdan Aldredge, first appeared in PremiumBeat.com. This is an excerpt.

The art of the comedy short film is actually nothing new, and can be traced back to the earliest days of film and cinema with the works of Buster Keaton and Charlie Chaplin. Here are some tips to finding the funny and creating quality comedy shorts and videos.

The initial planning helps set the tone. The goal is to explore ideas. You can do free association with just yourself and a piece of paper. Ideally, once you’ve “found the funny,” you can start putting those ideas to paper by planning your outline, script, and shots.

A good way to work is to cover your bases and make sure you have every shot you’d need to put together an edit. Then, once the rigid work is done, loosen things up and do as many takes as you can stand.

Another simple trick that can help out in the edit is to shoot several reaction shots. Comedy very much lives in faces.

When is comes to editing, comedy lends itself to quick cuts, especially to reactions.


… for Visual Effects

Tip #450: What Does Sharpening Do?

Sharpening adjusts the apparent focus of a clip.

The top is unsharpened, the bottom is significantly sharpened.

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Sharpening adjusts the apparent focus of a clip, without actually changing its focus.

Sharpening adjusts the contrast at the edges of objects in an image to improve their apparent focus. What our eye sees as “focus” is actually the sharpness of the edges between a foreground object and the background. If the edges are sharp, our eye considers the image in focus. If not, we consider the image – or that part of the image at least – blurry.

Unsharp Masking (which is the preferred method of sharpening) enhances the contrast between two adjacent edges. Our eye perceives that improved contrast as improved focus, though nothing about the focus of an image has changed.

When using Unsharp Mask, a little goes a long way. A Radius setting between 1.5 and 4 will yield perceptible results without making the image look like bad VHS tape.


… for Codecs & Media

Tip #451: Audio Compression for Podcasts

You can compress audio a lot, without damaging quality.

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If you are compressing audio for podcasts, where it’s just a few people talking, you can make this a very small file by taking advantage of some key audio characteristics.

To set a baseline, an hour of 16-bit, 48k uncompressed stereo audio (WAV or AIF) is about 660 MB. (1 minute of stereo = 11 MB, 1 minute of mono = 5.5 MB).

If we are posting this to our own web site, streaming it live where bandwidth requirements make a difference, or posting it to service that charges for storage, we want to make our file as small as possible, without damaging quality. Here’s what you need to know.

Since people only have one mouth, if all they are doing is talking, not singing with a band, you don’t need stereo. Mono is fine.

This reduces file size by 50%.

NOTE: Mono sounds play evenly from both left and right speakers placing the sound of the audio in the middle between them.

According to the Nyquist Theorem, dividing sample rate by 2 determines maximum frequency response. Human speech maxes out below 10,000 Hz. This means that compressing at a 32K sample rate retains all the frequency characteristics of the human voice. (32 / 2 = 16K Hz, well above frequencies used for human speech.)

This reduces file size by another 33%.

Without doing any compression, our 660 MB one hour audio file is reduced to about 220 MB.

Finally, using your preferred compression software, set the compression data rate to 56 kbps. This creates about a 25 MB file for a one-hour show. (About 95% file size reduction from the original file.)

And for podcasts featuring all-talk, it will sound great.


… for Codecs & Media

Tip #453: What is WebM?

WebM is supported by Mozilla, Firefox, Opera and Google Chrome.

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Developed and owned by Google, WebM is an audiovisual media file format. It is primarily intended to offer a royalty-free alternative to use in the HTML5 video and the HTML5 audio elements. It has a sister project WebP for images. The development of the format is sponsored by Google, and the corresponding software is distributed under a BSD license. There is some dispute, however, if WebM is truly royalty-free.

According to Wikipedia, native WebM support by Mozilla Firefox, Opera, and Google Chrome was announced at the 2010 Google I/O conference. Internet Explorer 9 requires third-party WebM software. Safari for macOS which relied on QuickTime to play web media until Safari 12, still does not have native support for WebM.

VLC media player, MPlayer, K-Multimedia Player and JRiver Media Center have native support for playing WebM files Android also supports WebM.

Here’s a link to learn more.


… for Codecs & Media

Tip #454: More Than You Need to Know – About Codecs

20 different codecs – all easy to compare.

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I was wandering around Wikipedia and discovered this comparison table of twenty popular media “containers,” their features and related codecs. This is fascinating to explore, simply due to the diversity.

Even if you don’t understand all of this – and I don’t – it is still fun to look at. Why? Because this puts key features of popular codecs all in one place, making them easy to review and compare.

Here’s a link to learn more.


… for Random Weirdness

Tip #423: 7 Reasons to Add Narration

Narration adds power, speeds action and consolidates back-story.

Narration adds power, speeds action and consolidates back-story. (Image courtesy of pexels.com.)

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This article, written by Jourdan Aldredge, first appeared in PremiumBeat. This is an excerpt.

For filmmakers, narration is truly a powerful tool — voice-over narration helps us understand what we’re seeing. Regardless of where you are in production, here are seven reasons you should consider using voice-over narration in your project.

  • Beef Up Your Narrative. Adding narration can be a great way to beef up your narrative to turn a section from a weakness into a strength.
  • Accelerate Exposition. Set things up much more quickly than otherwise possible.
  • Add Depth to a Character.
  • Lay Out the Broad Strokes. Especially with sequels, this helps jump start the action by quickly filling in the back-story.
  • Make Your Film More Active.
  • Add Humor to Your Scenes. Similar to making films more active, adding voice-over narration can also add more humor to your scenes.
  • Raise Issues of Reliability. If you are looking to add narration to your project, it’s also worth considering making it less than reliable. An unreliable narrator can cause a very drastic thematic response when the truth is revealed to the audience.

… for Apple Motion

Tip #433: Why Display Alpha Channels

The alpha channel displays the transparency in a clip.

The top image is in color, the lower image shows its transparency.

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One of the options in the top right corner of the Motion Viewer is the ability to display the alpha channel of the current project. (You’ll find it in the menu under the color square.) But, why would you need this?

The alpha channel, like the red, blue and green channels, displays the amount of transparency associated with each pixel. For instance, in this screen shot, does the gradient in the top, color, image fade to black or transparent? It’s impossible to tell.

However, when you look at the bottom image, which displays transparency, it is easy to see that the image fades from solid black (transparent) to solid white (opaque). (Shades of gray represent differing amounts of translucency.)

Remember, the alpha channel doesn’t show color, it shows transparency.


… for Visual Effects

Tip #436: What is a B-spline Curve?

B-splines are used to create shapes with no sharp corners.

An example of an open-ended B-spline curve.

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B-spline curves (short for Basis spline) are frequently used to create shapes because, unlike Bézier curves, B-splines have no corners.

A B-spline is a combination of flexible bands that pass through a number of points (called control points) to create smooth curves. These functions enable the creation and management of complex shapes and surfaces using a number of points. B-spline and Bézier functions are applied extensively for shape optimization.

B-splines can be open (where the ends are not connected, as in this screen shot), or closed.

The shape of the B-spline is determined by moving the nodes, the red dots in this illustration. These act as magnets, attracting the shape of the curve as the nodes move.

Neither Premiere nor Final Cut support B-splines, but After Effects and Motion do.

EXTRA CREDIT

An extension of B-splines are NURBS (short for “non-uniform rational B-splines”). The big benefit to NURBS is that they can exist in three dimensions. I’d, ah, show you the equations for these, but they make my brain hurt.


… for Codecs & Media

Tip #427: Create a LUT in Photoshop

Photoshop can create LUTs that work in Premiere, Resolve or Final Cut Pro X.

Save LUT settings in Photoshop using the CUBE format.

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LUTs are a great way to take log or RAW images and convert them into something pleasing to look at. You can even use this technique for Rec. 709 media, which we use every day in HD projects.

Here’s a technique that creates LUTs that work in Premiere, Final Cut or Resolve.

  • In Photoshop, import a still frame from your video that you want to create a LUT for.
  • NOTE: This image needs to retain some detail in the highlights. TIFF or PNG are the best export formats to use.

  • Select the layer containing the image and choose Layer > New > Background from Layer. (This setting is important.)
  • Add at least one Adjustment layers, then adjust Levels and other settings to the adjustment layer to create the look you want.
  • NOTE: Do not adjust the image, only modify the adjustment layer.

Here’s the magic part – as long as you convert the image into a background and use adjustment layers, you can take your look and convert it into a LUT which can be opened in Premiere, Resolve, or Final Cut.

  • In Photoshop, choose File > Export > Color Lookup Tables.
  • Give the file a description that makes sense to you. Then, and this is a KEY step, select the CUBE format. This format is required by all our NLEs.
  • Click OK,give it a name and location, then save it.
  • Switch over to your NLE and import your new custom LUT and apply it to your footage.

Done. This LUT can be used across multiple projects and multiple NLEs.

EXTRA CREDIT

Here’s an article that walks you through all the steps in more detail.