H265/HEVC encoder which supports alpha channel?

[Gyan]

As I understand it, the current HEVC spec supports alpha channel (as 'Auxiliary Pictures'). Is there an encoder which implements that functionality? I don't believe x265 does. Atleast, the latest ffmpeg build doesn't accept yuva420p as output format.

[Jamaika]

I don't know about that. The files BPG also don't have the alpha channel. The alpha channel have the files JPG.

[Cornucopia]

Don't know what your trying to say here, @Jamaika...

BPG format spec DOES support alpha (see http://bellard.org/bpg/), doesn't mean any particular encoded file has it, nor that a particular implementation of the codec supports it.
JPG does not support transparency/alpha (without resorting to an odd, rare hack). And using JPG's DCT/block compression on an alpha channel is probably the worst thing you can do to its utility as an alpha.

@Gyan, I'm pretty sure that at this time there is NOT an encoder that implements this.

Scott

[Gyan]

Scott, including the reference encoder HM? I scanned the manual but am not sure if I missed it.

[Cornucopia]

Wasn't talking about reference encoder, but I also don't see anything pertinent at all about "alpha", "transparent", "transparency", "channel" or "mask" there, so I doubt it is helpful either. Check a branch, though. (that's also where you should find the 3D extensions)

Scott

[Jamaika]

BPG format spec DOES support alpha (see http://bellard.org/bpg/), doesn't mean any particular encoded file has it, nor that a particular implementation of the codec supports it.

I see alpha canal. I'm using version 0.9.5: bpgenc.exe -h. The alpha canal work if the import file has it.

-alphaq              set quantizer parameter for the alpha channel (default = same as -q value)

JPG does not support transparency/alpha (without resorting to an odd, rare hack). And using JPG's DCT/block compression on an alpha channel is probably the worst thing you can do to its utility as an alpha.

I'm sorry made a mistake. JPG use channel K.