Video quality and file size: compression and codec

All quality settings are on one project page - "Performance". There you decide how strongly to compress the file. There you also choose the frames per second, the codec and the container for the result. The app has no "bitrate" field. The file size is set by "File compression" and artifact reduction. This page is about quality and file size. About speed, the number of threads and memory use: performance.

How to open the quality settings

1. Open a project.
2. On the left is a rail of icons. The "OUTPUT" section opens the "Metadata", "Performance" and "Export" pages.
3. Choose the "Performance" page.

It is faster through the "Search settings..." field at the top of the window. Search looks through the names of the settings themselves, so type what you need to change: "file compression", "video codec", "container", "keyframe". The word "quality" will not lead to this page.

Three of these settings - "Video codec", "Container" and "Keyframe interval" - stay unavailable while the "Choose codec and container" switch is off. Search finds them, but you can change them only after turning on the switch. How search works: in the window description.

The highlight of the found setting fades in five seconds.

Does the app change the video resolution?

The app has no setting for the output file resolution. The tooltip of the "Scale video" setting says so. The scale of the image in the frame changes. The resolution of the file itself stays the same.

The other frame settings behave the same way. "Rotate video", "Crop edges" and camera zoom bring the frame back to the original size. A template draws all layers in a frame the size of the main video. The copy comes out the same size as the original.

Two cases are worth knowing separately.

Video shot vertically on a phone. In such a file the frame is often stored horizontally, with a "rotate" tag next to it. When such a file is imported, the app shows the "Rotation metadata found in videos" window and offers to fix it. Please agree. Otherwise the frame settings will calculate the size from the stored numbers, not from what you see.

An odd number of pixels on a side. The app cannot process such an original; the copy will not be created. Files with an odd side are rare.

"File compression": speed versus file size

Three items; a new project has "Minimum" selected.

• "Minimum" - barely compresses the video. Speeds up video creation. Greatly increases the file size. Suits you if speed matters and there is a lot of disk space.
• "Medium" - a balance of speed and final file size.
• "Maximum" - video creation takes longer than usual. In return the file takes less disk space. Suits work with a large number of videos.

For the cloud this is the most expensive setting in the app. Between "Minimum" and "Maximum" the bill per video differs about fourfold. A separate uniquification setting changes it by percents.

"Secondary presets": tuning for the material

Five items. By default the "Default" item is selected. It changes nothing.

• "Film" - for high-quality video. Applies a deblocking filter. It keeps textures, fine lines and roughness.
• "Animation\cartoon" - for drawn graphics: sharp edges, smooth colors.
• "Slideshow" - for galleries. In them still frames change sharply.
• "Grain preservation" - for old films. There grain and film defects matter.

The setting does not affect the cost in the cloud. By measurement, its contribution is indistinguishable from zero.

"Compression type": so that the file opens on an old device

Four items, "Default" by default. They do not affect the cost in the cloud either.

• "Default" - the most stable type. Videos open on all devices. The file size may grow by 20%.
• "Auto" - the app picks the type for each video. The file size does not change. Old devices may not open such a video.
• "L3.1" - optimized for Apple TV.
• "Baseline L3.1" - optimized for iPhone 3G, iPod touch 2nd generation and later.

"Set artifact reduction manually"

The switch is off by default. The tooltip says it directly: 99% of users do not need this setting. While it is off, the app picks the degree of reduction for each video by itself.

The switch opens a slider with five positions, from "Minimum" to "Maximum". In a new project it is set in the middle. The higher the degree of reduction, the larger the file. The tooltip mentions a difference of up to a hundred times. The setting barely affects the speed of video creation. In the cloud, the rightmost position of the slider costs about one and a half times as much as the leftmost.

Change it in one case only. The created videos have defects, and changing the "Compression type" does not remove them.

"Set frames per second"

The switch is off by default. It opens the "Frames per second (FPS)" field. Values are from 1 to 120; in a new project, 60. The tooltip states the rule like this. The higher the FPS, the smoother the animations and the larger the file.

What to know in advance:

• The setting is expensive. It noticeably increases both the bill for video creation in the cloud and RAM use. Only "File compression" is more expensive on this page.
• Only this setting changes the material size (GP), on which the cost in the cloud depends. The dialog before the start prints the line "The size (GP) is calculated from the requested N FPS, not from the frame rate of the originals". The price can both rise and fall. Example: at 24 frames per second there will be fewer frames on a 30-frame video and more on a 15-frame one.

"Choose codec and container"

While the switch is off, video creation works as before: H.264 + AAC + mp4. When it is on, the app opens four lists. The lists depend on each other. The container sets the available codecs, and the audio codec sets the audio frequencies. An incompatible pair cannot be chosen.

Container

The container is the extension of the output file. Five items: "MP4 (universal, social media)", "MOV (QuickTime, editing)", "MKV (accepts any codec)", "WebM (web, VP9/AV1 only)", "AVI (legacy)". It also sets the set of codecs below. WebM accepts only AV1/VP9 and Opus/Vorbis. ProRes works only in MOV and MKV.

Video codec

The tooltip explains the point of the choice. With the same image, different codecs give a different bitstream. The image is the same, but the file is built differently inside. Codecs cost differently. The most expensive are AV1 (libaom, slow) and H.265 / HEVC, the cheapest are MPEG-4 Part 2 and Xvid. The exact cost of a run is shown by the "Check before start" sheet. The tooltip has a warning: AV1 (libaom) encodes 90 times longer than H.264.

Hardware codecs (NVENC, Quick Sync, AMF) are visible in the list only if they really work on your device. Choosing such a codec rules out video creation in the cloud. Cloud machines run on processors; they have no graphics cards.

Audio codec and "Audio frequency"

The audio list depends on the container. AAC (universal), MP3, Opus (web) and Vorbis are available. There are also AC-3 (Dolby Digital), FLAC (lossless) and PCM 16-bit (uncompressed).

"Audio frequency" is a separate list: "Same as source", "44100 Hz", "48000 Hz". The tooltip says it directly: there is no audible difference. But changing the frequency changes the spectrum of the signal. That means the audio fingerprint of the file changes too. The setting is for uniquification, not for quality. The set of frequencies narrows for the codec: Opus encodes only at 48 kHz.

"Keyframe interval"

This is a separate switch in the same section. By default it is off. The range is from 1 to 500 frames. A new project has the range 30-250.

The setting rebuilds the inner structure of the file. The image does not change. The tooltip describes it as a setting that changes the file a lot and barely increases the cost. This is the only encoding parameter the app sets anew for each copy. Codecs, container and audio frequency are the same for the whole project. About ranges: How uniquification works.

"Limit logical processors per thread"

This setting is not about quality. It is there so that you can work at the computer while videos are being created. The switch opens the "Maximum logical processors per thread" field. The minimum is 1.

An example from the tooltip. The processor has 10 logical processors. You set 2 threads and 3 processors per thread. The app takes no more than 6. Their number is visible in Task Manager on the "CPU" tab.

The setting saves memory too. Usage was measured while creating 1080p video. With one logical processor per thread it took 511 MB. With the automatic number, 883 MB. About the window freezing: App is not responding.

Frequently asked questions

Where is the bitrate setting in the app?

There is none. The file size is set by "File compression" and "Set artifact reduction manually". The latter is off by default: the app picks the degree of reduction by itself. "Compression type" (up to 20% of the size) and "Set frames per second" have less effect.

Why is my graphics card's codec not in the list?

Hardware codecs are visible in the list only if they really work on your device. The app checks this with a test encoding.

Why did the cloud threads disappear after I chose a codec?

You chose a hardware codec: NVENC, Quick Sync or AMF. The cloud has no graphics cards. So the app sets the "Number of cloud threads" field to zero and locks it. Please choose a software codec. The cloud threads will come back. More: Video creation on the device and in the cloud.

Does the choice of codec change the similarity of copies?

The codec changes the structure of the file, not the image. The similarity check works on the picture, so neither the codec nor the "Keyframe interval" affects its score. More: Similarity check.