[FFmpeg-devel] [PATCH] avcodec: add Mandsoft Screen Capture Codec decoder

[Carl Eugen Hoyos]

2017-04-15 13:49 GMT+02:00 Paul B Mahol <onemda at gmail.com>:

> +    case 32: avctx->pix_fmt = AV_PIX_FMT_BGRA;   break;

(I am thankful for this patch and, yes, I believe we had this
discussion before.)
If this is a screen capture codec, I believe BGR0 is the correct
colorspace. I understand that you tested that the encoder can
really encode transparency but the issue - imo - is, that if the
codec is (or actually was) used to record 32bit Windows screens
then some parts of the screen will contain "0xff" as alpha value
and others (sprites?) will contain "0x00" producing funny output
if you just transcode to png.

In the past, I also put BGRA there (for some other codec) and
it was fixed after another developer tested the same sample I
had tested but (correctly!) explained that the output (that I
considered useful originally) makes no sense and the
colorspace (or actually the transparency in the output file) is
wrong.

(If this is not a screen capture codec, BGRA is of course
most likely correct.)

Please don't let this stop you!

Carl Eugen