[FFmpeg-devel] libavcodec/hapdec : add support for HapAphaOnly decoding

Carl Eugen Hoyos ceffmpeg at gmail.com
Thu Oct 5 10:34:40 EEST 2017

2017-09-28 11:14 GMT+02:00 Tom Butterworth <bangnoise at gmail.com>:
> On Wed, 27 Sep 2017 at 16:52 Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:

>> As long as FFmpeg does not have a native alpha-only
>> pix_fmt (I am not sure this would have any user-visible
>> advantage), single-layer 8bit formats should be decoded
>> as gray8.
> This would result in a transcode to another alpha-carrying codec
> incorrectly placing the alpha channel in the colour channels, and
> setting the alpha channel to solid. Likewise, API users would not
> be able to know the channel intentions of the decoded frame. I'd
> argue that either a new pixel format be added, or an existing
> format which carries alpha should be used, even if that has the
> cost of redundant colour channels.

Allow me to repeat my question:
How would the workflow look like that is easier if we use
RGBA instead of gray?

Carl Eugen

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