video: remove slice based filtering and video output

Slices allowed filtering or drawing video in horizontal bands or
blocks. This allowed working on the video in smaller units. In theory,
this could bring a performance win by lowering cache pressure, as you
didn't have to keep the whole video frame in cache while filtering,
only the slice.

In practice, the slice code path was barely used for the following
reasons:
- Multithreaded decoding with ffmpeg didn't use slices. The ffmpeg
  slice callback was disabled, because it can be called from another
  thread, and the mplayer video chain is not thread-safe.
- There was nothing that would turn "full" images into appropriate
  slices, so slices were rarely used.
- Most filters didn't actually support slices.

On the other hand, supporting slices lead to code duplication and more
complex code in general. I made some experiments and didn't find any
actual measurable performance improvements when using slices. Even
ffmpeg removed slices based filtering from libavfilter in favor of
simpler code.

The most broken thing about the slices code path is that slices can't
be queued, like it is done for images in vo.c.

1 files changed, 1 insertions, 10 deletions

diff --git a/video/filter/vf_sub.c b/video/filter/vf_sub.c
index 5b2a79a030..3307af0c90 100644
--- a/video/filter/vf_sub.c
+++ b/video/filter/vf_sub.c
@@ -104,12 +104,6 @@ static void get_image(struct vf_instance *vf, mp_image_t *mpi)
                                         FFMAX(mpi->width,  vf->priv->outw),
                                         FFMAX(mpi->height, vf->priv->outh));
 
-    if ((vf->dmpi->flags & MP_IMGFLAG_DRAW_CALLBACK) &&
-        !(vf->dmpi->flags & MP_IMGFLAG_DIRECT)) {
-        mp_tmsg(MSGT_ASS, MSGL_INFO, "Full DR not possible, trying SLICES instead!\n");
-        return;
-    }
-
     int tmargin = vf->priv->opt_top_margin;
     // set up mpi as a cropped-down image of dmpi:
     if (mpi->flags & MP_IMGFLAG_PLANAR) {
@@ -124,8 +118,6 @@ static void get_image(struct vf_instance *vf, mp_image_t *mpi)
     mpi->stride[0] = vf->dmpi->stride[0];
     mpi->width = vf->dmpi->width;
     mpi->flags |= MP_IMGFLAG_DIRECT;
-    mpi->flags &= ~MP_IMGFLAG_DRAW_CALLBACK;
-//	vf->dmpi->flags&=~MP_IMGFLAG_DRAW_CALLBACK;
 }
 
 static void blank(mp_image_t *mpi, int y1, int y2)
@@ -155,8 +147,7 @@ static void blank(mp_image_t *mpi, int y1, int y2)
 static int prepare_image(struct vf_instance *vf, mp_image_t *mpi)
 {
     int tmargin = vf->priv->opt_top_margin;
-    if (mpi->flags & MP_IMGFLAG_DIRECT
-	|| mpi->flags & MP_IMGFLAG_DRAW_CALLBACK) {
+    if (mpi->flags & MP_IMGFLAG_DIRECT) {
         vf->dmpi = mpi->priv;
         if (!vf->dmpi) {
             mp_tmsg(MSGT_ASS, MSGL_WARN, "Why do we get NULL??\n");