image_writer: default to lossless AVIF screenshots

Also change the example to crf=23. crf=32 is pretty bad quality, don't
give users bad usage ideas.

DOCS/interface-changes.rst

@@ -32,6 +32,7 @@ Interface changes
       `--sub-delay`
     - add the `--osd-bar-border-size` option
     - `--screenshot-avif-pixfmt` no longer defaults to yuv420p
+    - `--screenshot-avif-opts` defaults to lossless screenshot
  --- mpv 0.37.0 ---
     - `--save-position-on-quit` and its associated commands now store state files
       in %LOCALAPPDATA% instead of %APPDATA% directory by default on Windows.

DOCS/man/options.rst

@@ -4566,7 +4566,7 @@ Screenshot
     Specifies libavcodec options for selected encoder. For more information,
     consult the FFmpeg documentation.
 
-    Default: ``usage=allintra,crf=32,cpu-used=8,tune=ssim``
+    Default: ``usage=allintra,crf=0,cpu-used=8``
 
     Note: the default is only guaranteed to work with the libaom-av1 encoder.
     Above options may not be valid and or optimal for other encoders.
@@ -4575,8 +4575,8 @@ Screenshot
 
     .. admonition:: Example
 
-        "``--screenshot-avif-opts=crf=32,aq-mode=complexity``"
-            sets the crf to 32 and quantization (aq-mode) to complexity based.
+        "``--screenshot-avif-opts=crf=23,aq-mode=complexity``"
+            sets the crf to 23 and quantization (aq-mode) to complexity based.
 
 ``--screenshot-sw=<yes|no>``
     Whether to use software rendering for screenshots (default: no).

video/image_writer.c

@@ -61,9 +61,8 @@ const struct image_writer_opts image_writer_opts_defaults = {
     .avif_encoder = "libaom-av1",
     .avif_opts = (char*[]){
         "usage",    "allintra",
-        "crf",      "32",
+        "crf",      "0",
         "cpu-used", "8",
-        "tune",     "ssim",
         NULL
     },
     .tag_csp = true,