As technology has evolved, the methods of displaying video have had to adapt. In previous generations, a common process of displaying video was known as interlacing. However, as screens have moved away from analog setups, interlacing video can sometimes produce visual effects like jagged screens. To help modernize visuals for digital setups, deinterlacing has become useful to avoid those visual errors.
What is interlaced video?
Interlaced video was formerly the standard way to display images on a screen. It splits each frame into two parts that alternate rapidly, creating the illusion of a complete image.
This technique was used in older broadcast systems to save bandwidth while maintaining smooth motion. You may recognize interlaced video formats from older standards like 480i or 1080i, where the “i” indicates interlacing.
Interlacing worked for older CRT TVs. However, it causes problems for modern digital displays. These displays are made to work with progressive video. Progressive video, or “p” formats like 1080p, displays all the lines of a frame in a single pass, resulting in clearer images.
Despite its age, interlaced video hasn’t disappeared entirely. Many legacy broadcasts and physical formats like DVDs still use interlaced formats.
Interlaced refresh rates can handle motion-heavy content well. This includes sports or live events in low-bandwidth areas. However, when viewed on modern devices that primarily use progressive scanning, interlaced video can appear jagged.
How does deinterlacing work?
Deinterlacing is the process of converting interlaced video into progressive video. Interlaced video divides each frame into two fields. Deinterlacing combines these fields to make a full frame. This full frame is better for progressive displays.
There are several techniques for deinterlacing, each with its own strengths and weaknesses:
Weaving:
This method simply combines the odd and even fields into a single frame. While it’s fast, it often results in noticeable motion artifacts during fast-moving scenes.
Blending:
Blending merges the two fields by averaging them, which reduces motion artifacts but can create a slightly blurred image.
Interpolation:
This more advanced technique analyzes the motion between fields and generates new pixels to create smoother, sharper images. It’s commonly used in high-quality streaming and broadcasting.
Each method has its purpose. However, for video streaming, interpolation is often better. It can manage fast motion with few interruptions.
For streaming platforms, smooth playback across multiple devices is necessary. Many streams still use interlaced formats, especially for live events, where reducing bandwidth is needed. Without proper deinterlacing, these videos may look distorted on progressive displays such as smartphones and modern TVs.
Deinterlacing enhances visual quality by converting interlaced scans into progressive video, ensuring smooth, artifact-free playback. It also ensures device compatibility by enabling interlaced content to display seamlessly on progressive screens. It also helps live streaming by using interlaced refresh rates. This saves bandwidth and keeps visuals high-quality for viewers.
While deinterlacing is essential for delivering quality video, it comes with challenges: High-quality deinterlacing techniques like interpolation demand significant processing power. Real-time deinterlacing can also introduce latency, and balancing visual quality with processing speed remains difficult for motion-heavy content.
Resi’s ProPresenter Stream allows broadcasters to utilize deinterlacing using existing hardware. By utilizing the Reliable Streaming Protocol (RSP), we ensure your content looks its best on any device.