[FFmpeg-devel] [PATCH 36/36] avcodec/mpegvideo_enc: Remove dead code at compile time

[Andreas Rheinhardt]

Michael Niedermayer:
> On Fri, Dec 24, 2021 at 04:23:32AM +0100, Andreas Rheinhardt wrote:
>> There are no encoders for interlaced dct that support 4:4:4.
> 
> i dont remember why its not supported but
> why not add 4:4:4 interlaced dct support ?
> 
> just thinking as you already work on the code, that would seem to me
> the "more interresting" route than to optimize that out
> 
> nothing againt this patch of course, thats fine too
> 
> thx
> [...]
> 

There are two encoders that support interlaced DCT: mpeg2video and
mpeg4. Our encoder for the former supports 420 and 422; the format also
allows 444. I don't really know how much is missing for supporting this
(it's probably more than just hardcoding a third chroma format in
ff_mpeg1_encode_mb()). And honestly, I don't really want to reread the
mpeg-2 spec to find out, because it is nearly 2022 and MPEG-2 is
obsolete and legacy.

- Andreas