video/converter: increase the number of cache lines for resampling

The exising hardcoded max default does not account for the possible
-1 offset when retrieving lines for resampling.  As a result, when
another chain has the same number of cache lines (4), the resample
operation would be attempting to generate 5 lines with a cache size
of 4 and would overwrite the first cache line.

Fixes https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/issues/821

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/938>

diff --git a/gst-libs/gst/video/video-converter.c b/gst-libs/gst/video/video-converter.c
index 3bfee92..7d921a7 100644 (file)
--- a/gst-libs/gst/video/video-converter.c
+++ b/gst-libs/gst/video/video-converter.c
@@ -851,7 +851,8 @@ chain_upsample (GstVideoConverter * convert, GstLineCache * prev, gint idx)
     prev = convert->upsample_lines[idx] = gst_line_cache_new (prev);
     prev->write_input = TRUE;
     prev->pass_alloc = TRUE;
-    prev->n_lines = 4;
+    /* XXX: why this hardcoded value? */
+    prev->n_lines = 5;
     prev->stride = convert->current_pstride * convert->current_width;
     gst_line_cache_set_need_line_func (prev,
         do_upsample_lines, idx, convert, NULL);
@@ -1959,7 +1960,8 @@ chain_downsample (GstVideoConverter * convert, GstLineCache * prev, gint idx)
     prev = convert->downsample_lines[idx] = gst_line_cache_new (prev);
     prev->write_input = TRUE;
     prev->pass_alloc = TRUE;
-    prev->n_lines = 4;
+    /* XXX: why this hardcoded value? */
+    prev->n_lines = 5;
     prev->stride = convert->current_pstride * convert->current_width;
     gst_line_cache_set_need_line_func (prev,
         do_downsample_lines, idx, convert, NULL);