Update `sharpness` comments to mention loop filter adjustment

Bug: aomedia:375221136
Change-Id: I7b080860baea98d61624d517095e38907360275e

aom/aomcx.h

diff --git a/aom/aomcx.h b/aom/aomcx.h
index 2070e80..255a891 100644
--- a/aom/aomcx.h
+++ b/aom/aomcx.h
@@ -233,10 +233,16 @@
    * unsigned int parameter.
    *
    * This parameter controls the level at which rate-distortion optimization of
-   * transform coefficients favours sharpness in the block.
+   * transform coefficients favors sharpness in the block.
    *
-   * Valid range: 0..7. The default is 0. Values 1-7 will avoid eob and skip
-   * block optimization and will change rdmult in favour of block sharpness.
+   * Valid range: 0..7. The default is 0.
+   *
+   * Values 1-7 will avoid eob and skip block optimization and will change
+   * rdmult in favor of block sharpness.
+   *
+   * In all-intra mode: it also sets the `loop_filter_sharpness` syntax element
+   * in the bitstream. Larger values increasingly reduce how much the filtering
+   * can change the sample values on block edges to favor perceived sharpness.
    */
   AOME_SET_SHARPNESS = AOME_SET_ENABLEAUTOALTREF + 2,  // 16
 

av1/arg_defs.c

diff --git a/av1/arg_defs.c b/av1/arg_defs.c
index 7aef17c..1c06f5b 100644
--- a/av1/arg_defs.c
+++ b/av1/arg_defs.c
@@ -280,10 +280,11 @@
   .save_as_annexb = ARG_DEF(NULL, "annexb", 1, "Save as Annex-B"),
   .noise_sens = ARG_DEF(NULL, "noise-sensitivity", 1,
                         "Noise sensitivity (frames to blur)"),
-  .sharpness = ARG_DEF(NULL, "sharpness", 1,
-                       "Bias towards block sharpness in rate-distortion "
-                       "optimization of transform coefficients "
-                       "(0..7), default is 0"),
+  .sharpness =
+      ARG_DEF(NULL, "sharpness", 1,
+              "Bias towards block sharpness in rate-distortion optimization of "
+              "transform coefficients and (in allintra mode only) reduce block "
+              "edge filtering for better sharpness (0..7), default is 0"),
   .static_thresh =
       ARG_DEF(NULL, "static-thresh", 1, "Motion detection threshold"),
   .auto_altref =

av1/encoder/encoder.h

diff --git a/av1/encoder/encoder.h b/av1/encoder/encoder.h
index f111559..6bfaff2 100644
--- a/av1/encoder/encoder.h
+++ b/av1/encoder/encoder.h
@@ -819,9 +819,15 @@
 typedef struct {
   /*!
    * Controls the level at which rate-distortion optimization of transform
-   * coefficients favours sharpness in the block. Has no impact on RD when set
-   * to zero (default). For values 1-7, eob and skip block optimization are
-   * avoided and rdmult is adjusted in favour of block sharpness.
+   * coefficients favors sharpness in the block. Has no impact on RD when set
+   * to zero (default).
+   *
+   * For values 1-7, eob and skip block optimization are
+   * avoided and rdmult is adjusted in favor of block sharpness.
+   *
+   * In all-intra mode: it also sets the `loop_filter_sharpness` syntax element
+   * in the bitstream. Larger values increasingly reduce how much the filtering
+   * can change the sample values on block edges to favor perceived sharpness.
    */
   int sharpness;