avcodec/libaomenc: add support for setting arbitrary libaom options

A new key & value API lets us gain access to newly added parameters
without adding explicit support for them in our wrapper. Add an
option utilizing this functionality in a similar manner to other
encoder libraries' wrappers.

Signed-off-by: Bohan Li <bohanli@google.com>

doc/encoders.texi

@@ -1684,6 +1684,17 @@ Enable interintra compound. Default is true.
 @item enable-smooth-interintra (@emph{boolean}) (Requires libaom >= v2.0.0)
 Enable smooth interintra mode. Default is true.
 
+@item aom-params
+Set libaom options using a list of @var{key}=@var{value} pairs separated
+by ":". For a list of supported options, see @command{aomenc --help} under the
+section "AV1 Specific Options".
+
+For example to specify libaom encoding options with @option{-aom-params}:
+
+@example
+ffmpeg -i input -c:v libaom-av1 -b:v 500K -aom-params tune=psnr:enable-tpl-model=1 output.mp4
+@end example
+
 @end table
 
 @section libsvtav1

libavcodec/libaomenc.c

@@ -124,6 +124,7 @@ typedef struct AOMEncoderContext {
     int enable_diff_wtd_comp;
     int enable_dist_wtd_comp;
     int enable_dual_filter;
+    AVDictionary *aom_params;
 } AOMContext;
 
 static const char *const ctlidstr[] = {
@@ -874,6 +875,20 @@ static av_cold int aom_init(AVCodecContext *avctx,
         codecctl_int(avctx, AV1E_SET_ENABLE_INTRABC, ctx->enable_intrabc);
 #endif
 
+#if AOM_ENCODER_ABI_VERSION >= 23
+    {
+        AVDictionaryEntry *en = NULL;
+
+        while ((en = av_dict_get(ctx->aom_params, "", en, AV_DICT_IGNORE_SUFFIX))) {
+            int ret = aom_codec_set_option(&ctx->encoder, en->key, en->value);
+            if (ret != AOM_CODEC_OK) {
+                log_encoder_error(avctx, en->key);
+                return AVERROR_EXTERNAL;
+            }
+        }
+    }
+#endif
+
     // provide dummy value to initialize wrapper, values will be updated each _encode()
     aom_img_wrap(&ctx->rawimg, img_fmt, avctx->width, avctx->height, 1,
                  (unsigned char*)1);
@@ -1299,6 +1314,9 @@ static const AVOption options[] = {
     { "enable-masked-comp",           "Enable masked compound",                            OFFSET(enable_masked_comp),           AV_OPT_TYPE_BOOL, {.i64 = -1}, -1, 1, VE},
     { "enable-interintra-comp",       "Enable interintra compound",                        OFFSET(enable_interintra_comp),       AV_OPT_TYPE_BOOL, {.i64 = -1}, -1, 1, VE},
     { "enable-smooth-interintra",     "Enable smooth interintra mode",                     OFFSET(enable_smooth_interintra),     AV_OPT_TYPE_BOOL, {.i64 = -1}, -1, 1, VE},
+#if AOM_ENCODER_ABI_VERSION >= 23
+    { "aom-params",                   "Set libaom options using a :-separated list of key=value pairs", OFFSET(aom_params), AV_OPT_TYPE_DICT, { 0 }, 0, 0, VE },
+#endif
     { NULL },
 };