Video and Audio Encoding Format Specifications

Codec Selection for Professional Webcasting

Codec selection balances quality, compatibility, latency, and computational requirements. These specifications provide guidance on appropriate codecs for different webcasting applications and the parameters needed to achieve streaming quality standards.

Video Codecs

H.264/AVC (Advanced Video Coding)

H.264/AVC remains the baseline recommendation for maximum compatibility across devices and platforms. Use Main or High profile depending on target devices. Recommended settings include 2-second GOP for live streaming, B-frame usage limited for low-latency applications, and CBR or constrained VBR for consistent delivery.

HEVC/H.265 (High Efficiency Video Coding)

HEVC provides approximately 50% bitrate reduction compared to H.264 at equivalent quality. Recommended for 4K content and bandwidth-constrained applications where device support is confirmed. Main profile recommended; Main10 for HDR content. Appropriate for premium content where encoding resources are available.

AV1 (AOMedia Video 1)

AV1 offers royalty-free advanced compression suitable for high-scale distribution. Currently recommended primarily for on-demand content due to encoding complexity. Device support growing but should be verified for target audiences. Provides excellent quality at lower bitrates when playback support is confirmed.

Audio Codecs

AAC (Advanced Audio Coding)

AAC-LC is the recommended audio codec for maximum compatibility. Use AAC-HE for bitrates below 64 kbps. Stereo encoding at 128 kbps minimum for professional speech content; 256 kbps or higher for music-focused content. Sample rate should match source or use 48 kHz for broadcast compatibility.

Opus

Opus provides excellent quality at low bitrates and is royalty-free. Recommended for WebRTC-based applications and where browser playback is primary. Superior to AAC at bitrates below 64 kbps. Growing support in streaming platforms makes Opus increasingly viable for professional applications.

Container Formats

fMP4 (Fragmented MP4)

fMP4 is the recommended container for adaptive bitrate streaming including HLS and DASH. Supports all standard video and audio codecs. Fragment duration of 2-6 seconds balances latency and efficiency. CMAF (Common Media Application Format) provides compatibility across HLS and DASH players.

Adaptive Bitrate Ladder

Professional webcasts should include multiple quality tiers for adaptive bitrate delivery. Recommended ladder includes minimum three tiers from mobile (540p) through standard (720p) to high definition (1080p). Additional 4K tier for premium content. Specific bitrate targets are detailed in member documentation for each resolution and codec combination.