From d16293e76cf8b53b8bef589e69823f7864ee14f4 Mon Sep 17 00:00:00 2001
From: Paul B Mahol <onemda@gmail.com>
Date: Fri, 5 Feb 2021 15:26:10 +0100
Subject: [PATCH] avfilter/vf_lensfun: display list of possible values if user
 supplied none

---
 libavfilter/vf_lensfun.c | 37 +++++++++++++++++++++++--------------
 1 file changed, 23 insertions(+), 14 deletions(-)

diff --git a/libavfilter/vf_lensfun.c b/libavfilter/vf_lensfun.c
index 95f00e8c10..430daa941b 100644
--- a/libavfilter/vf_lensfun.c
+++ b/libavfilter/vf_lensfun.c
@@ -136,20 +136,6 @@ static av_cold int init(AVFilterContext *ctx)
     const lfCamera **cameras;
     const lfLens **lenses;
 
-    if (!lensfun->make) {
-        av_log(ctx, AV_LOG_FATAL, "Option \"make\" not specified\n");
-        return AVERROR(EINVAL);
-    } else if (!lensfun->model) {
-        av_log(ctx, AV_LOG_FATAL, "Option \"model\" not specified\n");
-        return AVERROR(EINVAL);
-    } else if (!lensfun->lens_model) {
-        av_log(ctx, AV_LOG_FATAL, "Option \"lens_model\" not specified\n");
-        return AVERROR(EINVAL);
-    }
-
-    lensfun->lens = lf_lens_create();
-    lensfun->camera = lf_camera_create();
-
     db = lf_db_create();
     if (lf_db_load(db) != LF_NO_ERROR) {
         lf_db_destroy(db);
@@ -157,6 +143,29 @@ static av_cold int init(AVFilterContext *ctx)
         return AVERROR_INVALIDDATA;
     }
 
+    if (!lensfun->make || !lensfun->model) {
+        const lfCamera *const *cameras = lf_db_get_cameras(db);
+
+        av_log(ctx, AV_LOG_FATAL, "Option \"make\" or option \"model\" not specified\n");
+        av_log(ctx, AV_LOG_INFO, "Available values for \"make\" and \"model\":\n");
+        for (int i = 0; cameras && cameras[i]; i++)
+            av_log(ctx, AV_LOG_INFO, "\t%s\t%s\n", cameras[i]->Maker, cameras[i]->Model);
+        lf_db_destroy(db);
+        return AVERROR(EINVAL);
+    } else if (!lensfun->lens_model) {
+        const lfLens *const *lenses = lf_db_get_lenses(db);
+
+        av_log(ctx, AV_LOG_FATAL, "Option \"lens_model\" not specified\n");
+        av_log(ctx, AV_LOG_INFO, "Available values for \"lens_model\":\n");
+        for (int i = 0; lenses && lenses[i]; i++)
+            av_log(ctx, AV_LOG_INFO, "\t%s\t(make %s)\n", lenses[i]->Model, lenses[i]->Maker);
+        lf_db_destroy(db);
+        return AVERROR(EINVAL);
+    }
+
+    lensfun->lens = lf_lens_create();
+    lensfun->camera = lf_camera_create();
+
     cameras = lf_db_find_cameras(db, lensfun->make, lensfun->model);
     if (cameras && *cameras) {
         lf_camera_copy(lensfun->camera, *cameras);