Codecs Av01008m08 399 Opus 251 New Jun 2026

Check with ffprobe on a sample file:

: This refers to the YouTube-specific Format Code (Format ITTAG). When extracting video streams, YouTube assigns static numeric labels to specific resolutions and codec configurations. ITTAG 399 is explicitly reserved for 1080p Full HD video at 30 frames per second encoded natively in AV1 . Understanding Audio Format: opus (251)

: This seems to be a specific identifier or code, possibly related to a particular piece of hardware, a codec specification, or a unique identifier for a media file or stream. Without a direct reference, it's hard to provide a precise explanation, but it could relate to:

When the system selects "399," it is prioritizing efficiency. It is saying, "Give this user the best possible visual fidelity with the least amount of data," saving the server money and saving the user buffering time.

This long technical string maps directly to the ISO/IEC Media Format specification for AV1 bitstreams: codecs av01008m08 399 opus 251 new

: Indicates Level 3.1 operating at a Main tier data rate. Levels define the maximum processing limits, such as resolution and frame rate. Level 3.1 typically handles standard 720p or 1080p video resolutions at smooth frame rates. 08 : Represents an 8-bit color depth .

This article breaks down what this "new" codec combination means for users and content creators, focusing on AV1 (av01.0.08M.08) and Opus. 1. The Video Component: AV01008M08 (AV1)

So av01008m08 should be read as: av01.0.08M.08

The combination of AV1 video (with strings like av01.0.01M.08 ) and Opus audio (itag 251) is the for streaming, but it requires modern hardware or software. Check with ffprobe on a sample file: :

Are you looking to streams using these specific formats?

Are you trying to a video with these specific settings or troubleshoot playback issues?

This is the direction major platforms (YouTube, Netflix) are moving to reduce server costs and improve user experience on limited connections.

If you're reviewing or investigating the use of the Opus codec with specific settings (like "251") and a unique identifier or device specification ("AV01008M08" and "399"), consider the following: Understanding Audio Format: opus (251) : This seems

Video Codec: AV01.0.08M.08 (AV1) This string refers to a specific profile of the codec, often seen in YouTube's internal metadata. AV01 : Identifies the AV1 codec. 0 : Base profile. 08M : Level 4.1 (Main tier). 08 : 8-bit color depth. Performance : Offers 30-40% better compression than VP9.

AV1 allows for smoother HD streaming and significant data savings without sacrificing visual quality.

audio codec. In specific technical configurations—such as the av01.0.08M.08 profile for video and the