On Mon, 23 Apr 2018 20:25:40 +0200 (CEST) Marton Balint <c...@passwd.hu> wrote:
> On Sun, 22 Apr 2018, wm4 wrote: > > > On Sun, 22 Apr 2018 13:24:11 +0200 (CEST) > > Marton Balint <c...@passwd.hu> wrote: > > > >> On Fri, 20 Apr 2018, wm4 wrote: > >> > >> > On Thu, 19 Apr 2018 23:25:03 +0200 > >> > Marton Balint <c...@passwd.hu> wrote: > >> > > >> >> Signed-off-by: Marton Balint <c...@passwd.hu> > >> >> --- > >> >> doc/APIchanges | 3 +++ > >> >> libavutil/pixdesc.c | 3 +-- > >> >> libavutil/pixdesc.h | 8 ++------ > >> >> libavutil/tests/pixdesc.c | 4 ---- > >> >> libavutil/version.h | 2 +- > >> >> 5 files changed, 7 insertions(+), 13 deletions(-) > >> >> > >> >> diff --git a/doc/APIchanges b/doc/APIchanges > >> >> index 4f6ac2a031..d9b457e080 100644 > >> >> --- a/doc/APIchanges > >> >> +++ b/doc/APIchanges > >> >> @@ -15,6 +15,9 @@ libavutil: 2017-10-21 > >> >> > >> >> API changes, most recent first: > >> >> > >> >> +2018-04-xx - xxxxxxxxxx - lavu 56.16.100 - pixdesc.h > >> >> + Add AV_PIX_FMT_FLAG_ALPHA to AV_PIX_FMT_PAL8. > >> >> + > >> > >> [..] > >> > >> > > >> > Probably fine. While I like it, we also have to be careful about the > >> > consequences. Does it change FATE or the results of that pixfmt choosing > >> > function, avcodec_find_best_pix_fmt_of_list()? > >> > >> Fate passes. I am not sure about avcodec_find_best_pix_fmt_of_list(), but > >> since pixdesc_has_alpha() in avutil/pixdesc.c already considered PAL8 as a > >> format with alpha, I don't think it changes. > > > > Oh, interesting point. So this whole discussion is moot anyway, since > > it always suggested RGBA when converting PAL8 to a non-paletted RGB > > format? > > Only if has_alpha was true when the user called > avcodec_find_best_pix_fmt_of_list() or av_find_best_pix_fmt_of_2(). > > For avfiltergraph format negotiation or for ffmpeg.c automatic codec pixel > format selection, pal8 was not considered as a format with alpha > (nb_components % 2 == 0 check was used), so they called > av_find_best_pix_fmt_of_2() with has_alpha=false, therefore alpha loss was > not penalized. A subsequent patch takes care of that. Right. That's a bit of a mess. So if anyone thinks that's a problem, the avfilter code can still be special-cased, or we could introduce a non-alpha PAL format. LGTM anyway, it's a nice cleanup. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
