Every pixel on your screen reaches your eyes through one of two scanning methods- progressive and interlaced. Progressive scanning is a display method that draws every horizontal line of a video frame in a single pass, from top to bottom, producing a complete image at once. Interlaced scanning is a display method that splits each frame into two fields of odd and even lines, showing only half of the frame at a time.
Choosing the wrong scan type leads to combing artifacts, motion blur, and degraded video quality during live streams. This matters now more than ever as creators broadcast to platforms with different playback requirements.
Progressive video provides smoother motion and sharper images without the artifacts common in interlaced footage. For modern streaming workflows, progressive is the superior choice, while interlaced still appears in legacy broadcast infrastructure.
This guide will explain the key differences between progressive and interlaced scanning in streaming.
What Is Progressive Scanning?
Progressive scanning is a video display method that renders every horizontal line of a frame sequentially in one pass. The display starts at line 1 at the top of the screen. It draws each line in order, moving downward through every row of pixels. Once it reaches the bottom, the full frame is complete. Then it starts the next frame.
The “p” in resolution labels refers to progressive.
- 1080p means 1,080 horizontal lines drawn progressively to form a complete frame.
- 720p means 720 lines drawn the same way.
Because every frame is whole, progressive scan displays produce sharper still images and cleaner motion.
Progressive scan maintains the traditional film look and avoids jitter in still or slow-moving frames, making it suitable for movies and cinematic content. If you are configuring your encoder, understanding the best OBS settings for streaming will help you set progressive output correctly.
What Is Interlaced Scanning?
Interlaced scanning is a video display method that divides each frame into two alternating fields of odd and even lines. Field 1 draws the odd numbered lines: 1, 3, 5, 7, and so on. Field 2 draws the even lines: 2, 4, 6, 8, and so on. Together, these two half images combine to form one complete picture.
The “i” in resolution labels stands for interlaced.
1080i means 1,080 horizontal lines split across two interlaced fields.
480i was the standard for analog television in the NTSC system. Interlaced video technology was developed in the early 1930s to address bandwidth limitations in television broadcasting. It allowed broadcasters to send a video signal using only half the bandwidth per field while still creating the perception of smooth motion on CRT monitors.
The perceived frame rate of interlaced video can be effectively doubled without increasing bandwidth, as it displays two fields per frame.
How Progressive and Interlaced Scanning Work
Both methods deliver video to a screen. They differ in how they draw each frame.
Progressive process:
- The display starts at line 1 at the top.
- It draws every line in order: 1, 2, 3, 4, all the way down.
- It completes the entire video frame in a single pass.
- It moves to the next frame and repeats.
Progressive scan displays each frame sequentially from top to bottom, resulting in a smoother and more detailed image. Every refresh cycle produces a full image with no missing lines.
Interlaced process:
- The display starts at line 1.
- It draws only the odd scan lines: 1, 3, 5, 7 (Field 1).
- It returns to the top and draws the even lines: 2, 4, 6, 8 (Field 2).
- Both fields combine to form one single frame.
Each field contains only half the spatial information. The interlaced video scan method relies on the viewer’s eye blending the two fields together into what appears to be a complete image.
| Attribute | Progressive | Interlaced |
|---|---|---|
| Lines per pass | All lines (full frame) | Half the lines (one field) |
| Fields per frame | 1 (complete frame) | 2 (alternating fields) |
| Frame completeness | Full resolution every cycle | Full resolution across two fields |
| Bandwidth usage | Higher per frame | Lower per field |
| Motion clarity | Clean, no combing | Combing possible during fast motion |
| Common notation | 720p, 1080p | 480i, 1080i |
Progressive vs Interlaced: Key Differences
The differences between progressive and interlaced affect image clarity, motion smoothness, bandwidth consumption, and device compatibility. Here is a breakdown of all the differences across the attributes that matter most for video quality.
Image Quality and Clarity
Progressive video produces a sharper progressive image because every frame is spatially complete. The viewer’s screen receives a full image with every refresh. Interlaced formats can appear softer because each field contains only half the vertical resolution at any given moment.
Most modern digital displays are natively progressive. Playing an interlaced signal on these screens requires deinterlacing, which can reduce picture quality and introduce softness.
Motion Handling and Artifacts
Progressive scanning handles fast motion cleanly. There are no interlacing artifacts because every frame captures a single moment in time. Interlaced video can cause flickering during fast motion, while progressive is more stable and has less flicker. Interlaced video can introduce artifacts such as “combing” in fast-moving scenes, where the odd and even lines do not align properly.
These combing artifacts appear as jagged horizontal lines splitting across moving objects. Progressive scan minimizes these visible artifacts by displaying the entire video frame at once.
Bandwidth and File Size
Interlaced video conserves bandwidth by displaying only half of the frame at a time. This was crucial for early broadcast television when spectrum was limited. An interlaced signal uses roughly half the bandwidth per field compared to a full progressive frame. Progressive video requires more data for the same resolution because every frame is complete.
However, modern compression codecs like H.264 and H.265 have largely reduced this gap. Understanding video bitrate helps clarify how bandwidth relates to scan type in streaming workflows.
Device and Platform Compatibility
Modern displays, including LCD, LED, OLED screens, smartphones, and tablets, are natively progressive scan displays. They do not need any conversion to show progressive format content. Interlaced content requires a deinterlacing process on these devices, adding processing power overhead and potential quality loss. Streaming platforms like YouTube, Facebook, and Twitch prefer progressive input.
Legacy broadcast infrastructure, including cable TV and some satellite systems, still relies on interlaced mode. Creators who are multistreaming to multiple platforms should always send progressive video for the best compatibility.
Resolution Comparison: 1080p vs 1080i vs 720p
1080p delivers 1,920 by 1,080 pixels progressively. Every frame is a complete frame at full resolution. 1080i has the same pixel count, but it splits across two fields. Each field contains only 540 lines, so the effective per-field resolution is 1,920 by 540. 720p delivers 1,280 by 720 pixels progressively. It has a lower original resolution than 1080i, but every frame is whole.
High-frame-rate progressive video is preferred for fast-moving broadcasts like sports, as 720p at 60fps handles motion better than 1080i. Many broadcasters choose 720p over 1080i for this reason.
| Attribute | Progressive (1080p) | Interlaced (1080i) |
|---|---|---|
| Image sharpness | Full frame sharpness every cycle | Softer due to field splitting |
| Motion clarity | No combing, clean motion | Combing artifacts in fast motion |
| Bandwidth usage | Higher per frame | Lower per field |
| Modern display compatibility | Native, no conversion needed | Requires deinterlacing |
| Streaming platform support | Preferred by all major platforms | Accepted but deinterlaced server-side |
| Best for | Streaming, gaming, web video, modern screens | Broadcast TV, cable, satellite, legacy systems |
When to Use Progressive Scanning for Live Streaming
Progressive scanning is the standard for modern live streaming. Every major streaming platform is built to receive and deliver progressive scan video. Progressive video is ideal for most modern applications, including online streaming, gaming, and content viewed on modern screens.
Use progressive scanning when you are:
- Streaming to YouTube, Facebook, Twitch, or LinkedIn
- Broadcasting to multiple live streaming platforms at the same time
- Reaching viewers on mobile phones, tablets, and desktop computers
- Broadcasting events with fast motion, such as sports, concerts, or gaming
- Encoding with OBS, vMix, or a cloud-based live video production switcher
- Embedding live streams on your website using an HTML5 player
- Streaming at 720p or 1080p for adaptive bitrate delivery
Most encoders default to progressive output. Set your output to 1080p at 30fps for general content or 720p at 60fps for fast-motion content. These settings give you the best balance of video quality and bandwidth efficiency. Cloud-based production tools handle progressive natively, so no extra configuration is needed.
When Interlaced Scanning Still Makes Sense
Interlaced scanning is not dead. It persists in specific industries where legacy infrastructure remains the standard. Interlaced video is still widely used in cable and satellite TV due to its bandwidth efficiency while providing high resolution.
Interlaced remains relevant in these scenarios:
- Broadcast television networks transmitting in 1080i, such as CBS and NBC in the United States
- Cable and satellite distribution systems built on interlaced infrastructure
- SDI-based production workflows in traditional broadcast studios
- Regulatory or standards compliance requiring interlaced output for some ATSC 1.0 tv channels
- Archival content and older digital footage originally recorded in interlaced formats
Interlaced video was widely used in analog television systems throughout the 20th century. Many tv stations still rely on it for standard definition broadcasts and some HD channels. However, the transition from interlaced to progressive scanning began in the 1990s as digital technology improved. For anyone streaming to the internet, progressive or interlaced is not a difficult choice. Progressive is the clear winner. Interlaced relevance is confined to legacy broadcast pipelines and traditional tv channels.
How to Convert Interlaced Video to Progressive for Streaming
Deinterlacing is a video processing technique that converts interlaced footage into progressive frames by combining or interpolating the two fields. If you receive an interlaced signal from a capture card, SDI feed, or IP camera, you need to convert interlaced video to progressive before sending it to a streaming platform.
Here are the most common methods:
- In OBS Studio: Right-click the video source. Open Properties. Select Deinterlace and choose “Yadif” or “Blend.” Set your output to progressive. This handles the deinterlacing process in real time before encoding.
- In Handbrake: Open your interlaced file. Go to the Filters tab. Select Deinterlace and choose “Yadif.” Encode the output to MP4 with H.264 in progressive format. Field combination deinterlacing merges the even and odd fields into a single frame, converting formats like 60i to 30p, but it reduces the perceived frame rate by half.
- In FFmpeg: Use the yadif filter with this command: ffmpeg -i input.ts -vf yadif output.mp4. Motion compensation deinterlacing is a more sophisticated technique that analyzes movement across fields and modifies reconstruction methods accordingly, producing higher-quality results compared to simpler methods.
- In cloud-based switchers: Some cloud production tools handle deinterlacing automatically when ingesting feeds from SDI or IP cameras. If you are working with IP camera live streaming, check whether your platform converts the interlaced signal on ingest.
Always run the deinterlacing process before streaming to the internet. Sending interlaced video to YouTube or Facebook will result in visible combing artifacts on the viewer’s screen. The goal is to fill in the missing lines from each field and produce a clean progressive image.
How Scan Type Affects Your Live Streaming Quality
The scanning method you choose directly affects how your stream looks and performs across every device.
Bitrate efficiency: Progressive video encodes more efficiently with modern codecs like H.264 and H.265. Each frame is spatially complete, which gives the encoder a consistent full image to compress.
Interlaced content has temporal gaps between alternating fields that reduce compression efficiency. This means interlaced streams often need more data to achieve the same picture quality as progressive streams at the same resolution.
Viewer experience: On phones, tablets, laptops, and smart TVs, progressive content displays natively on most displays. There is no extra processing power required. Interlaced content requires client-side deinterlacing, and the quality of that conversion varies across devices. Some viewers will see combing artifacts or softness that degrades the experience.
Progressive scan displays each frame sequentially from top to bottom, providing a complete image at once, which is why it delivers smoother motion on every modern screen.
Adaptive bitrate delivery: Cloud transcoding for adaptive bitrate streaming works best with progressive source material. When the platform performs video transcoding to create multiple quality levels, progressive input produces cleaner output at every bitrate tier.
Interlaced sources can introduce quality loss during this process because the transcoder must handle the two-field structure before creating progressive output renditions.
Recommendation: Always send progressive video to your streaming platform. This ensures the best quality across all viewer devices, from mobile phones to smart TVs.
Final Thoughts
Progressive scanning delivers better video quality, cleaner motion, and broader compatibility for every modern streaming workflow. Castr handles progressive streaming natively with multi-CDN delivery, adaptive bitrate transcoding, and multistreaming to 30+ platforms. Start your free 7-day trial with Castr today. No credit card required.
