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, 3 insertions, 56 deletions

diff --git a/video/filter/vf_screenshot.c b/video/filter/vf_screenshot.c
index bb5ca517a0..29d2e0b1e0 100644
--- a/video/filter/vf_screenshot.c
+++ b/video/filter/vf_screenshot.c
@@ -37,7 +37,7 @@ struct vf_priv_s {
     mp_image_t *image;
     void (*image_callback)(void *, mp_image_t *);
     void *image_callback_ctx;
-    int shot, store_slices;
+    int shot;
 };
 
 //===========================================================================//
@@ -54,53 +54,8 @@ static int config(struct vf_instance *vf,
     return vf_next_config(vf,width,height,d_width,d_height,flags,outfmt);
 }
 
-static void start_slice(struct vf_instance *vf, mp_image_t *mpi)
-{
-    mpi->priv=
-    vf->dmpi=vf_get_image(vf->next,mpi->imgfmt,
-        mpi->type, mpi->flags, mpi->width, mpi->height);
-    if (vf->priv->shot) {
-        vf->priv->store_slices = 1;
-        if (!(vf->priv->image->flags & MP_IMGFLAG_ALLOCATED))
-            mp_image_alloc_planes(vf->priv->image);
-    }
-
-}
-
-static void memcpy_pic_slice(unsigned char *dst, unsigned char *src,
-                             int bytesPerLine, int y, int h,
-                             int dstStride, int srcStride)
-{
-    memcpy_pic(dst + h * dstStride, src + h * srcStride, bytesPerLine,
-               h, dstStride, srcStride);
-}
-
-static void draw_slice(struct vf_instance *vf, unsigned char** src,
-                       int* stride, int w,int h, int x, int y)
-{
-    if (vf->priv->store_slices) {
-        mp_image_t *dst = vf->priv->image;
-        int bp = (dst->bpp + 7) / 8;
-
-        if (dst->flags & MP_IMGFLAG_PLANAR) {
-            int bytes_per_line[3] = { w * bp, dst->chroma_width, dst->chroma_width };
-            for (int n = 0; n < 3; n++) {
-                memcpy_pic_slice(dst->planes[n], src[n], bytes_per_line[n],
-                                 y, h, dst->stride[n], stride[n]);
-            }
-        } else {
-            memcpy_pic_slice(dst->planes[0], src[0], dst->w*bp, y, dst->h,
-                             dst->stride[0], stride[0]);
-        }
-    }
-    vf_next_draw_slice(vf,src,stride,w,h,x,y);
-}
-
 static void get_image(struct vf_instance *vf, mp_image_t *mpi)
 {
-    // FIXME: should vf.c really call get_image when using slices??
-    if (mpi->flags & MP_IMGFLAG_DRAW_CALLBACK)
-      return;
     vf->dmpi= vf_get_image(vf->next, mpi->imgfmt,
                            mpi->type, mpi->flags/* | MP_IMGFLAG_READABLE*/, mpi->width, mpi->height);
 
@@ -119,7 +74,7 @@ static int put_image(struct vf_instance *vf, mp_image_t *mpi, double pts)
 {
     mp_image_t *dmpi = (mp_image_t *)mpi->priv;
 
-    if(!(mpi->flags&(MP_IMGFLAG_DIRECT|MP_IMGFLAG_DRAW_CALLBACK))){
+    if(!(mpi->flags&(MP_IMGFLAG_DIRECT))){
         dmpi=vf_get_image(vf->next,mpi->imgfmt,
                                     MP_IMGTYPE_EXPORT, 0,
                                     mpi->width, mpi->height);
@@ -134,11 +89,7 @@ static int put_image(struct vf_instance *vf, mp_image_t *mpi, double pts)
 
     if(vf->priv->shot) {
         vf->priv->shot=0;
-        mp_image_t image;
-        if (!vf->priv->store_slices)
-            image = *dmpi;
-        else
-            image = *vf->priv->image;
+        mp_image_t image = *dmpi;
         image.flags &= ~MP_IMGFLAG_ALLOCATED;
         image.w = vf->priv->image->w;
         image.h = vf->priv->image->h;
@@ -146,7 +97,6 @@ static int put_image(struct vf_instance *vf, mp_image_t *mpi, double pts)
         image.display_w = vf->priv->image->display_w;
         image.display_h = vf->priv->image->display_h;
         vf->priv->image_callback(vf->priv->image_callback_ctx, &image);
-        vf->priv->store_slices = 0;
     }
 
     return vf_next_put_image(vf, dmpi, pts);
@@ -188,13 +138,10 @@ static int vf_open(vf_instance_t *vf, char *args)
     vf->control=control;
     vf->put_image=put_image;
     vf->query_format=query_format;
-    vf->start_slice=start_slice;
-    vf->draw_slice=draw_slice;
     vf->get_image=get_image;
     vf->uninit=uninit;
     vf->priv=malloc(sizeof(struct vf_priv_s));
     vf->priv->shot=0;
-    vf->priv->store_slices=0;
     vf->priv->image=NULL;
     return 1;
 }