[vlc-devel] [PATCH 5/5] video_output: change the deinterlacing filter before displaying the picture

[Steve Lhomme]

There is a problem with this, which preexisted this patch.

Calling ThreadChangeFilters in ThreadDisplayPreparePicture can flush the 
displayed.current picture. If the "pre-rendered" picture was the 
displayed.next and not the displayed.current then we end up with the 
displayed.next set and not the displayed.current. (and there's an assert 
to check this doesn't happen)

I'm looking into solutions...

On 2020-11-06 15:32, Steve Lhomme wrote:
> The first deinterlaced picture should not be displayed without passing through
> the deinterlacer. It's even more crucial when the source picture only contains
> one field, at half the real height.
> 
> Now filters are only updated before filtering a decoded picture, rather than
> before a picture is displayed. It is still done outside of the frame timing
> checks.
> ---
>   src/video_output/interlacing.c  |  2 +-
>   src/video_output/video_output.c | 25 +++++++++----------------
>   2 files changed, 10 insertions(+), 17 deletions(-)
> 
> diff --git a/src/video_output/interlacing.c b/src/video_output/interlacing.c
> index e6fe8d23b4e..761be2d6180 100644
> --- a/src/video_output/interlacing.c
> +++ b/src/video_output/interlacing.c
> @@ -179,7 +179,7 @@ void vout_SetInterlacingState(vout_thread_t *vout, vout_thread_private_t *sys, b
>           msg_Dbg(vout, "Detected %s video",
>                    is_interlaced ? "interlaced" : "progressive");
>           sys->interlacing.is_interlaced = is_interlaced;
> -        ChangeInterlacing(vout, false);
> +        ChangeInterlacing(vout, true);
>       }
>       if (is_interlaced)
>           sys->interlacing.date = vlc_tick_now();
> diff --git a/src/video_output/video_output.c b/src/video_output/video_output.c
> index 0a71457d4f9..20e569e173c 100644
> --- a/src/video_output/video_output.c
> +++ b/src/video_output/video_output.c
> @@ -121,7 +121,6 @@ typedef struct vout_thread_sys_t
>       struct {
>           vlc_tick_t  date;
>           vlc_tick_t  timestamp;
> -        bool        is_interlaced;
>           picture_t   *decoded; // decoded picture before passed through chain_static
>           picture_t   *current;
>           picture_t   *next;
> @@ -1091,6 +1090,15 @@ static picture_t *ThreadDisplayPreparePicture(vout_thread_sys_t *vout, bool reus
>                           vlc_video_context_Release(sys->filter.src_vctx);
>                       sys->filter.src_vctx = pic_vctx ? vlc_video_context_Hold(pic_vctx) : NULL;
>   
> +                    sys->filter.changed = true;
> +                }
> +
> +                vout_SetInterlacingState(&vout->sys.obj, &sys->sys.private, !decoded->b_progressive);
> +
> +                if (sys->filter.changed ||
> +                    sys->sys.private.interlacing.has_deint != sys->filter.new_interlaced)
> +                {
> +                    sys->sys.private.interlacing.has_deint = sys->filter.new_interlaced;
>                       ThreadChangeFilters(vout);
>                   }
>   
> @@ -1139,7 +1147,6 @@ static picture_t *ThreadDisplayPreparePicture(vout_thread_sys_t *vout, bool reus
>   
>           sys->displayed.decoded       = picture_Hold(decoded);
>           sys->displayed.timestamp     = decoded->date;
> -        sys->displayed.is_interlaced = !decoded->b_progressive;
>   
>           picture = filter_chain_VideoFilter(sys->filter.chain_static, sys->displayed.decoded);
>       }
> @@ -1464,15 +1471,6 @@ static int ThreadDisplayPicture(vout_thread_sys_t *vout, vlc_tick_t *deadline)
>   
>       assert(sys->clock);
>   
> -    vlc_mutex_lock(&sys->filter.lock);
> -    if (sys->filter.changed ||
> -        sys->sys.private.interlacing.has_deint != sys->filter.new_interlaced)
> -    {
> -        sys->sys.private.interlacing.has_deint = sys->filter.new_interlaced;
> -        ThreadChangeFilters(vout);
> -    }
> -    vlc_mutex_unlock(&sys->filter.lock);
> -
>       if (deadline)
>           *deadline = VLC_TICK_INVALID;
>   
> @@ -1841,7 +1839,6 @@ static int vout_Start(vout_thread_sys_t *vout, vlc_video_context *vctx, const vo
>       sys->displayed.decoded       = NULL;
>       sys->displayed.date          = VLC_TICK_INVALID;
>       sys->displayed.timestamp     = VLC_TICK_INVALID;
> -    sys->displayed.is_interlaced = false;
>   
>       sys->step.last               = VLC_TICK_INVALID;
>       sys->step.timestamp          = VLC_TICK_INVALID;
> @@ -1913,10 +1910,6 @@ static void *Thread(void *object)
>           }
>   
>           wait = ThreadDisplayPicture(vout, &deadline) != VLC_SUCCESS;
> -
> -        const bool picture_interlaced = sys->displayed.is_interlaced;
> -
> -        vout_SetInterlacingState(&vout->sys.obj, &sys->sys.private, picture_interlaced);
>       }
>   }
>   
> -- 
> 2.26.2
> 
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