Broadcast Video Codecs Explained

Intra-frame (I-Frame Only) Codecs

Examples: Apple ProRes, Avid DNxHR, Sony XAVC-I.

Intra-frame compression treats video like a rapid sequence of discrete JPEG images. Every single frame is compressed individually without referencing the frames before or after it.

• Pros: Zero latency rendering. Extremely fast to edit because the CPU doesn't have to decode adjacent frames to display the current one. Preserves exact pixel data and color subsampling (4:2:2, 4:4:4).
• Cons: Massive file sizes. A continuous 1080p60 ProRes 422 stream requires roughly 293 Mbps of sustained disk bandwidth.
• Use Case: Original camera capture (OFC), NLE timelines, live playback servers (HyperDecks, EVS), and master archiving.

Long-GOP (Inter-frame) Codecs

Examples: H.264 (AVC), H.265 (HEVC), Sony XAVC-L.

Group of Pictures (GOP) compression achieves massive bandwidth savings by analyzing movement between frames over time.

It generates one full frame (I-Frame), followed by a sequence of predictive frames (P-frames) that only store the pixels that changed from the I-Frame, and Bi-directional frames (B-frames) that reference both past and future data.

• Pros: Extremely tight file sizes. A visually pristine 1080p60 stream can be encoded at just 8 Mbps using HEVC.
• Cons: Heavy processing load. To edit frame 14, your CPU must decode the I-frame at frame 1, and calculate the math through frames 2-13. This causes timeline stuttering on weaker machines. Hardware encode/decode chips (NVENC, QuickSync) are mandatory for live workloads.
• Use Case: Final delivery to consumer screens (YouTube, Broadcast Muxers), SRT streaming, and long-form proxy recording.

Color Depth: 8-bit vs. 10-bit

While subsampling (4:2:2) deals with color resolution, Bit Depth deals with the precision of those colors:

• 8-bit: 256 shades per channel (16.7 million colors). Standard for web and sRGB.
• 10-bit: 1,024 shades per channel (1.07 billion colors). Mandatory for HDR (High Dynamic Range) and "Log" shooting.