50% frame drop with interlaced content regression

stz.ts

831fa3cd0f981fa20803013c7c12435a37173f92 is the first bad commit
commit 831fa3cd0f981fa20803013c7c12435a37173f92
Author: Lyndon Brown <jnqnfe@gmail.com>
Date:   Sat Jan 26 08:51:36 2019 +0000

    deinterlace: purge MMX/MMXEXT
    
    notes:
     - this removes all SIMD acceleration for x86/x86_64. originally this work
       started by converting the MMX code to SSE2, then purged remaining
       artifacts, but a build error on android has blocked that work from
       being merged for now. this commit thus takes a different approach of
       simply purging the old MMX/MMXEXT code first, with getting the SSE2
       implementation working to be done as a follow up.
     - the `EndMMX()` function is retained (renamed to `EndSSE()`) because it
       is still used under the merge code. the `emms` instruction will be
       replaced with an `sfence` instruction separately, as more appropriate.

 modules/video_filter/Makefile.am                 |   1 -
 modules/video_filter/deinterlace/algo_ivtc.c     |   4 ---
 modules/video_filter/deinterlace/algo_phosphor.c | 139 ++------------------------------------------------------------------------------------------------
 modules/video_filter/deinterlace/algo_x.c        | 232 ++------------------------------------------------------------------------------------------------------------------------------------------------------------------
 modules/video_filter/deinterlace/algo_x.h        |   4 +--
 modules/video_filter/deinterlace/algo_yadif.c    |   5 ----
 modules/video_filter/deinterlace/deinterlace.c   |  10 +-------
 modules/video_filter/deinterlace/deinterlace.h   |   2 +-
 modules/video_filter/deinterlace/helpers.c       | 227 ----------------------------------------------------------------------------------------------------------------------------------------------------------------
 modules/video_filter/deinterlace/merge.c         |  34 ++----------------------
 modules/video_filter/deinterlace/merge.h         |  22 ++++------------
 modules/video_filter/deinterlace/mmx.h           | 256 -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 modules/video_filter/deinterlace/yadif.h         |   3 ---
 modules/video_filter/deinterlace/yadif_x86.asm   |   7 -----
 14 files changed, 15 insertions(+), 931 deletions(-)
 delete mode 100644 modules/video_filter/deinterlace/mmx.h

changed milestone to %4.0

added Component::Video: filters label

see !55

What's missing exactly? Other ISA only have assembler for merge, not the more advanced algos. If it's anything else, how is it not a problem on Arm devices?

In any case, it seems to me that we don't have any x86 assembly coder anymore so, eh.