Media Apple FCP X

… for Codecs & Media

Tip #1322: What is Hardware-Accelerated Encoding?

Larry Jordan – LarryJordan.com

Hardware compression sets the standard for both speed and quality.

The Effects panel in After Effects, showing which effects are accelerated.

Topic $TipTopic

In the past, when we needed to render or export a file, the software in the NLE did all the work. This worked fine, but took a long time. As video production became more of a mass market, there was incentive for hardware developers to incorporate video compression circuits onto the CPU.

This was MUCH faster than software compression, but, for video pros, still not fast enough.

Now, video compression is moving from the CPU to the GPU. For example, according to Adobe, Adobe Premiere Pro and Adobe Media Encoder can take advantage of available GPUs on your system to distribute the processing load between the CPU and the GPU to get better performance. Currently, most of the processing is done by CPU and GPU assists in processing certain tasks and features.

The Mercury Playback Engine (GPU Accelerated) renderer is used to render GPU accelerated effects and features.
Here is the list of GPU accelerated effects in Adobe Premiere Pro. To identify the GPU accelerated effects, navigate to the Effects panel and look for the Accelerated Effects icon.

Apart from processing these effects, the Mercury Playback Engine (GPU Accelerated) is used for image processing, resizes, color space conversions, recoloring and more. It is also used for timeline playback/scrubbing and full-screen playback using Mercury Transmit.

EXTRA CREDIT

A wild card in hardware acceleration is the new Apple silicon chips. In the past, hardware acceleration for both H.264 and HEVC was handled by the T-2 chip.
With the move to Apple silicon, all compression is now done using the M1 chip.

From a quality point of view, my studies show that for most compression, hardware acceleration looks the same as software compression, yet processes files much more quickly.


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… for Codecs & Media

Tip #1325: Why Is an Audio Fade Called +3 dB?

Larry Jordan – LarryJordan.com

Audio is a Strange Beast

Four different fade shapes available in Apple Final Cut Pro.

Topic $TipTopic

Unlike video, audio levels are logarithmic. For example, whenever the audio level increases (or decreases) around 10 dB, the perceived volume is doubled (or cut in half). These log values also have an impact in cross-fading between clips.

A +3 dB transition adds a 3 dB increase in volume to both clips in the middle of a cross-fade. If the software did not add this “bump,” the cross-fade would sound fainter in the middle of a transition, then louder at each end.

When fading to or from black, a straight-line (linear) transition is best. When cross-fading between two clips, both of which have continuous audio, a +3 dB transition will sound better.

EXTRA CREDIT

Some software allows you to change the shape of the curve manually. These rules still apply, but manual adjustments allow much greater control over how the transition sounds.

Still, the general rule of audio is: Whatever sounds the best to you IS most likely the best.


… for Random Weirdness

Tip #1307: Top 10 Streaming Movies in 2020

Larry Jordan – LarryJordan.com

This list was compiled by JustWatch.com.

JustWatch.com logo.

Topic $TipTopic

This article, written by Jason Hellerman, first appeared in NoFilmSchool.com. This is a summary.

JustWatch.com, an international streaming guide, compiled a list of what people were streaming the most this year.

Here’s the list:

  1. Parasite
  2. Knives Out
  3. Jojo Rabbit
  4. Contagion
  5. Once Upon a Time… in Hollywood
  6. 1917
  7. Joker
  8. The Lighthouse
  9. Little Women
  10. Ford v. Ferrari

NOTE: This tracked movies viewed only in the US from Jan. 1 – Dec. 1, 2020.


… for Codecs & Media

Tip #1281: Larger Frame Sizes Protect Projects

Larry Jordan – LarryJordan.com

Frame sizes will continue to increase, here’s how they benefit current projects.

Topic $TipTopic

We are in the middle of determining the “optimum” frame size for video projects as frame sizes continue to scale up. New projects are consistently shooting in 4k frame sizes, with cameras pushing up to 8K frame sizes and beyond.

First, while it could be argued that we can’t actually SEE 4K in most situations, that hasn’t stopped distributors from requesting it. However, even if we are creating HD projects, there is a value in shooting larger frame sizes. Recently, Jason Boone wrote a blog about the benefits of scaling larger frame sizes to fit smaller projects.

  • Reframe a shot. 4K provides so many extra pixels to choose from, you can convert a wide shot into a close-up. However, cutting into the frame won’t change depth of field, so the image won’t look the same as if you had zoomed in.
  • Use the same take multiple times. Using the same take for both wide shots and close-ups makes it seem as though you have two cameras. The benefit is that where talent is looking change. The disadvantage is that background and depth of field won’t change either.
  • Create camera moves. Using keyframes you can create movement where there was none in the original shot. However, like moves on a still, elements won’t change position as they would if you used a dolly on set.
  • Stabilize your footage. This is powerful. Stabilization always zooms into a shot. By having lots of extra pixels to work with, the image won’t lose detail or sharpness.
  • Adjust the image for graphics. There’s nothing worse than graphics you can’t read. 4K gives us extra pixels for scaling and repositioning.

4K may not be visible to the eye, but it can be a BIG benefit in post. And the same holds true for larger frame sizes yet – provided your storage is fast and large enough to hold it!


… for Adobe Premiere Pro CC

Tip #1266: Interpreting an Alpha Channel

Larry Jordan – LarryJordan.com

Alpha channels are the magic that make compositing and most effects possible.

Viewing the alpha channel: White is opaque, black is transparent & gray is translucent.

Topic $TipTopic

The process of adding an alpha channel to an image – at the developer level – is highly complex. Fortunately, we don’t need to understand how the channel is added to take advantage of it.

Just as the red, blue and green channels describe the amount of red, blue or green in each pixel, the alpha channel describes the amount of transparency in each pixel. An alpha channel provides a way to store images and their transparency information in a single file without disturbing the color channels.

Many file formats can include an alpha channel, including Adobe Photoshop, ElectricImage, TGA, TIFF, EPS, PDF, and Adobe Illustrator. ProRes, AVI and QuickTime (saved at a bit depth of Millions Of Colors+), also can contain alpha channels, depending upon the codecs used to generate these file types.

Alpha channels store transparency information in files in one of two ways: straight or premultiplied. Although the alpha channels are the same, the color channels differ.

With straight (or unmatted) channels, transparency information is stored only in the alpha channel, not in any of the visible color channels. With straight channels, the effects of transparency aren’t visible until the image is displayed in an application that supports straight channels.

With premultiplied (or matted) channels, transparency information is stored in the alpha channel and also in the visible RGB channels, which are multiplied with a background color. The colors of semitransparent areas, such as feathered edges, are shifted toward the background color in proportion to their degree of transparency.

Some software lets you specify the background color with which the channels are premultiplied; otherwise, the background color is usually black or white.

Straight channels retain more accurate color information than premultiplied channels. While premultiplied channels are compatible with a wider range of programs, such as Apple QuickTime Player.

Often, the choice of whether to use images with straight or premultiplied channels has been made before you receive the assets to edit and composite. Premiere Pro and After Effects recognize both straight and premultiplied channels, but only the first alpha channel they encounter in a file containing multiple alpha channels.

ProRes 4444 is a good choice when you need to create or transfer clips with alpha channels.

Alpha channels are supported in all NLEs, and there are dozens of articles on the web detailing how to work with them to create a variety of different effects.


… for Codecs & Media

Tip #1273: What is an MKV File?

Larry Jordan – LarryJordan.com

MKV files, like QuickTime or MXF, are containers that hold media files.

Topic $TipTopic

This morning, a reader emailed me a question asking whether MKV files are supported in Big Sur. That got me thinking about what an MKV file is.

According to HowToGeek.com, “MKV files are actually multimedia container formats. An MKV container can incorporate audio, video, and subtitles into a single file—even if those elements use different types of encoding….
MKV container files were designed to be future proof, meaning that the files would not become outdated.”

Features of an MKV file include:

  • Fast seeking
  • Chapter, menu, and metadata support
  • Different selectable audio and video streams
  • Online streaming compatibility
  • Subtitle (hard-coded and soft-coded) support
  • Error recovery, which allows for playback of corrupted files

The MKV container itself also supports almost any audio and video format, making the format highly adaptive and easy to use. However, while the MKV file may not become outdated, the players that support them can. For example, QuickTime Player does not support MKV files.

Here’s a list, published by Wondershare, of the top 10 MKV players for Windows, Mac, iOS and Android devices.

So, as for compatibility, if your MKV player runs on Big Sur, the MKV files should play as well.


… for Apple Motion

Tip #1239: Change Clip Speed by Dragging

Larry Jordan – LarryJordan.com

Option-dragging the Out changes the speed of a clip.

Option-dragging the Out of a clip changes its speed.

Topic $TipTopic

Here’s a way, suggested by MediaBox Productions, to change the speed of a clip in Motion – without using the Inspector.

  • In the mini-timeline, press the Option key and click the Out (i.e. the last frame of a clip). The pointer turns into the curved retime pointer.
  • Drag the Out point left to speed the clip up, or right to slow the clip down.

The change in speed for the clip is displayed in the yellow change box above the clip (see screen shot).


… for Codecs & Media

Tip #1257: Repair a Broken QuickTime Movie

Larry Jordan – LarryJordan.com

Here are a variety of tools you can use to convert, repair and play QuickTime files.

Topic $TipTopic

QuickTime is a very flexible media container, but, when it breaks, it breaks badly.  There are three big problems with video files that won’t play:

  • The file lacks an extension
  • The codec is no longer supported
  • The QuickTime movie itself is broken

The first problem generally shows up when you store media files on a server. Servers don’t use the Mac operating system, which means that all files on a server must use an extension. Sometimes, simply adding the correct extension – either .mov or .mp4 – will allow a movie to play.

A bigger problem with video files are codecs that are no longer supported. Apple removed support for 32-bit codecs in macOS Catalina, which means many early videos no longer play. Even my audio-only files, stored in early QuickTime movies, won’t play.

To play older files, I have several older computers that I’m not upgrading. As well, Kyno, from LessPain Software will convert older codecs, even if the movies won’t play on a current operating system.

The third problem, though is trickier. When dealing with QuickTime movies, the entire file needs to be perfect for the video to play. If one small part of a QuickTime movie is damaged, the entire movie is dead. For this reason, much though I love QuickTime, I’m also converting any movies that need future proofing into MPEG-4. Keep the bit rate high – 10 Mbps or above – to retain high image quality. Then, I have both a ProRes version and an MPEG-4 version. One of those should last.

If the media file is damaged, I’ve had great success using Wondershare UniConverter. While this hasn’t fixed all my files, it HAS fixed most of them. This software has a free trial that converts the first third of any video. If it can convert a third, the paid version (subscription or purchase) will convert all of it. I used this software to recover over 100 files that wouldn’t play.

As well, the folks at Digital Rebellion also have a family of QuickTime repair utilities called Pro Maintenance Tools. I’m hoping to give it a try in the next week or two. I have great respect for their developers!


… for Codecs & Media

Tip #1238: An Overview of Alpha Channels

Larry Jordan – LarryJordan.com

Alpha channels are the magic that make compositing and most effects possible.

Viewing the alpha channel: White is opaque, black is transparent & gray is translucent.

Topic $TipTopic

The process of adding an alpha channel to an image – as a developer – is highly complex. Fortunately, we don’t need to understand how the channel is added to take advantage of it.

Just as the red, blue and green channels describe the amount of red, blue or green in each pixel, the alpha channel describes the amount of transparency in each pixel. An alpha channel provides a way to store images and their transparency information in a single file without disturbing the color channels.

Many file formats can include an alpha channel, including Adobe Photoshop, ElectricImage, TGA, TIFF, EPS, PDF, and Adobe Illustrator. ProRes, AVI and QuickTime (saved at a bit depth of Millions Of Colors+), also can contain alpha channels, depending upon the codecs used to generate these file types.

Alpha channels store transparency information in files in one of two ways: straight or premultiplied. Although the alpha channels are the same, the color channels differ.

With straight (or unmatted) channels, transparency information is stored only in the alpha channel, not in any of the visible color channels. With straight channels, the effects of transparency aren’t visible until the image is displayed in an application that supports straight channels.

With premultiplied (or matted) channels, transparency information is stored in the alpha channel and also in the visible RGB channels, which are multiplied with a background color. The colors of semitransparent areas, such as feathered edges, are shifted toward the background color in proportion to their degree of transparency.

Some software lets you specify the background color with which the channels are premultiplied; otherwise, the background color is usually black or white.

Straight channels retain more accurate color information than premultiplied channels. While premultiplied channels are compatible with a wider range of programs, such as Apple QuickTime Player.

Often, the choice of whether to use images with straight or premultiplied channels has been made before you receive the assets to edit and composite. Premiere Pro and After Effects recognize both straight and premultiplied channels, but only the first alpha channel they encounter in a file containing multiple alpha channels.

Use ProRes 4444 when you need to create or transfer clips with alpha channels.

Alpha channels are supported in all NLEs, and there are dozens of articles on the web detailing how to work with them to create a variety of different effects.


… for Codecs & Media

Tip #1236: Comparing ProRes 422 HQ, 422 vs. 422 LT

Larry Jordan – LarryJordan.com

Apple ProRes logo.

Topic $TipTopic

I got into a discussion recently about the differences between ProRes 422 and ProRes 422 HQ. After that, I did some research and here’s what I learned.

NOTE: This material was taken from Apple’s ProRes White Paper.

Apple ProRes 422 HQ: A higher-data-rate version of Apple ProRes 422 that preserves visual quality at the same high level as Apple ProRes 4444, but for 4:2:2 image sources. With widespread adoption across the video post-production industry, Apple ProRes 422 HQ offers visually lossless preservation of the highest-quality professional HD video that a single-link HD-SDI signal can carry. This codec supports full-width, 4:2:2 video sources at 10-bit pixel depths, while remaining visually lossless through many generations of decoding and re-encoding. The target data rate of Apple ProRes 422 HQ is approximately 220 Mbps at 1920 x 1080 and 29.97 fps.

Apple ProRes 422: A high-quality compressed codec offering nearly all the benefits of Apple ProRes 422 HQ, but at 66 percent of the data rate for even better multistream, real-time editing performance. The target data rate of Apple ProRes 422 is approximately 147 Mbps at 1920 x 1080 and 29.97 fps.

Apple ProRes 422 LT: A more highly compressed codec than Apple ProRes 422, with roughly 70 percent of the data rate and 30 percent smaller file sizes. This codec is perfect for environments where storage capacity and data rate are at a premium. The target data rate of Apple ProRes 422 LT is approximately 102 Mbps at 1920 x 1080 and 29.97 fps.

Which would I use personally?

  • ProRes 422 HQ. Only if the camera recorded source footage in this format.
  • ProRes 422. Anything shot by a non-HDR camera.
  • ProRes 422 LT. All review copies sent to clients or collaborators to decrease file size.

I’m interested in your comments.