XAVC Class 480 – What is it?

workshops-275 XAVC Class 480 - What is it?

Has anyone else noticed that Adobe now include XAVC Class 480 in the codec options for exporting XAVC from Adobe Premiere via Media Encoder?

In case you don’t know what it is, class 480 is the 480Mb/s version of 4K XAVC. This gives a bit rate of…… drum roll……. 480Mb/s at 24/25/30fps. At 50 and 60fps it runs at a whopping 960Mb/s, this is the top limit for XAVC in it’s current form.

Sony’s PMW-F5/F55 and the FS7 currently record XAVC using Class 300 which is up to 300Mb/s at 24/25/30fps or 600Mb/s at 50/60p. So as you can see Class 480 has the potential to improve the compressed image quality from these cameras still further should it ever make it into a camera. Looking at what the cameras can currently do I’m not sure that this is possible with existing SxS or XQD media. 960Mb/s is the same data rate as Sonys 16 bit 24fps raw and it’s not possible to record that to SxS cards.

Coming back to Premier: Some interesting things happen in Premiere if you try to export an XAVC originated project out using Class 480. If the clips in your timeline are not adjusted in any way, in other words; exactly as shot, then if you export and choose Class 480 nothing happens to the footage. Premiere will “smart” export them exactly as they are as Class 300. This means that there will be absolutely no loss of image quality as the clip is not re-compressed. However if the original clip has been adjusted, for example graded, re-sized, a caption added etc then the clip will be encoded at 480Mb/s. From what I can tell where you have a mix of treated and untreated clips in a project Premiere is smart enough to pass through the untreated clips while bumping up any treated clips to 480.

Class 480 is seen as a mastering format by Sony. The extra data and lower compression makes it particularly suited to HDR productions.

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