diff --git a/CHANGELOG.md b/CHANGELOG.md
index 01b48b3..f482f3f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Separate audio and subtitle stream copying options.
 
+### Fixed
+
+- Null pointer dereference in Real-ESRGAN, Real-CUGAN, and RIFE processors when frame conversion fails.
+- Vulkan hardware device context leak on error paths in libplacebo filter initialization.
+- Incorrect spdlog format string using printf-style specifiers instead of fmt-style placeholders.
+- Division by zero in CLI progress display within the first second of processing.
+- `unhook_ffmpeg_logging` disabling all FFmpeg logging instead of restoring the default callback.
+
 ## [6.4.0] - 2025-01-24
 
 ### Added
diff --git a/src/avutils.cpp b/src/avutils.cpp
index 06daada..9c50790 100644
--- a/src/avutils.cpp
+++ b/src/avutils.cpp
@@ -126,7 +126,7 @@ AVPixelFormat get_encoder_default_pix_fmt(const AVCodec* encoder, AVPixelFormat
 
     if (target_pix_fmt != AV_PIX_FMT_NONE && best_pix_fmt != target_pix_fmt) {
         logger()->warn(
-            "Incompatible pixel format '%s' for encoder '%s'; auto-selecting format '%s'",
+            "Incompatible pixel format '{}' for encoder '{}'; auto-selecting format '{}'",
             av_get_pix_fmt_name(target_pix_fmt),
             encoder->name,
             av_get_pix_fmt_name(best_pix_fmt)
diff --git a/src/filter_realcugan.cpp b/src/filter_realcugan.cpp
index 57c16f4..6598e10 100644
--- a/src/filter_realcugan.cpp
+++ b/src/filter_realcugan.cpp
@@ -184,6 +184,10 @@ int FilterRealcugan::filter(AVFrame* in_frame, AVFrame** out_frame) {
 
     // Convert ncnn::Mat to AVFrame
     *out_frame = conversions::ncnn_mat_to_avframe(out_mat, out_pix_fmt_);
+    if (*out_frame == nullptr) {
+        logger()->error("Failed to convert ncnn::Mat to AVFrame");
+        return AVERROR(ENOMEM);
+    }
 
     // Rescale PTS to encoder's time base
     (*out_frame)->pts = av_rescale_q(in_frame->pts, in_time_base_, out_time_base_);
diff --git a/src/filter_realesrgan.cpp b/src/filter_realesrgan.cpp
index 0e85c34..abfd100 100644
--- a/src/filter_realesrgan.cpp
+++ b/src/filter_realesrgan.cpp
@@ -124,6 +124,10 @@ int FilterRealesrgan::filter(AVFrame* in_frame, AVFrame** out_frame) {
 
     // Convert ncnn::Mat to AVFrame
     *out_frame = conversions::ncnn_mat_to_avframe(out_mat, out_pix_fmt_);
+    if (*out_frame == nullptr) {
+        logger()->error("Failed to convert ncnn::Mat to AVFrame");
+        return AVERROR(ENOMEM);
+    }
 
     // Rescale PTS to encoder's time base
     (*out_frame)->pts = av_rescale_q(in_frame->pts, in_time_base_, out_time_base_);
diff --git a/src/interpolator_rife.cpp b/src/interpolator_rife.cpp
index 29ca7c2..918256e 100644
--- a/src/interpolator_rife.cpp
+++ b/src/interpolator_rife.cpp
@@ -128,6 +128,10 @@ int InterpolatorRIFE::interpolate(
 
     // Convert ncnn::Mat to AVFrame
     *out_frame = conversions::ncnn_mat_to_avframe(out_mat, out_pix_fmt_);
+    if (*out_frame == nullptr) {
+        logger()->error("Failed to convert ncnn::Mat to AVFrame");
+        return AVERROR(ENOMEM);
+    }
 
     // Rescale PTS to encoder's time base
     (*out_frame)->pts = av_rescale_q(in_frame->pts, in_time_base_, out_time_base_);
diff --git a/src/libplacebo.cpp b/src/libplacebo.cpp
index f889350..e5e1c47 100644
--- a/src/libplacebo.cpp
+++ b/src/libplacebo.cpp
@@ -44,6 +44,7 @@ int init_libplacebo(
     AVFilterGraph* graph = avfilter_graph_alloc();
     if (!graph) {
         logger()->error("Unable to create filter graph.");
+        av_buffer_unref(&vk_hw_device_ctx);
         return AVERROR(ENOMEM);
     }
 
@@ -52,6 +53,7 @@ int init_libplacebo(
     if (!buffersrc) {
         logger()->error("Filter 'buffer' not found.");
         avfilter_graph_free(&graph);
+        av_buffer_unref(&vk_hw_device_ctx);
         return AVERROR_FILTER_NOT_FOUND;
     }
 
@@ -90,6 +92,7 @@ int init_libplacebo(
     if (ret < 0) {
         logger()->error("Cannot create buffer source.");
         avfilter_graph_free(&graph);
+        av_buffer_unref(&vk_hw_device_ctx);
         return ret;
     }
 
@@ -100,6 +103,7 @@ int init_libplacebo(
     if (!libplacebo_filter) {
         logger()->error("Filter 'libplacebo' not found.");
         avfilter_graph_free(&graph);
+        av_buffer_unref(&vk_hw_device_ctx);
         return AVERROR_FILTER_NOT_FOUND;
     }
 
@@ -123,6 +127,7 @@ int init_libplacebo(
     if (ret < 0) {
         logger()->error("Cannot create libplacebo filter.");
         avfilter_graph_free(&graph);
+        av_buffer_unref(&vk_hw_device_ctx);
         return ret;
     }
 
diff --git a/src/logger_manager.cpp b/src/logger_manager.cpp
index 0f0e0dd..cc482f5 100644
--- a/src/logger_manager.cpp
+++ b/src/logger_manager.cpp
@@ -109,7 +109,7 @@ void LoggerManager::hook_ffmpeg_logging() {
 }
 
 void LoggerManager::unhook_ffmpeg_logging() {
-    av_log_set_callback(nullptr);
+    av_log_set_callback(av_log_default_callback);
 }
 
 }  // namespace logger_manager
diff --git a/tools/video2x/src/video2x.cpp b/tools/video2x/src/video2x.cpp
index 6a669f9..c70f37c 100644
--- a/tools/video2x/src/video2x.cpp
+++ b/tools/video2x/src/video2x.cpp
@@ -170,7 +170,9 @@ int main(int argc, char** argv) {
 
                 // Calculate estimated time remaining
                 int64_t frames_remaining = total_frames - processed_frames;
-                double processing_rate = static_cast<double>(processed_frames) / time_elapsed;
+                double processing_rate = time_elapsed > 0
+                    ? static_cast<double>(processed_frames) / time_elapsed
+                    : 0.0;
                 int time_remaining =
                     static_cast<int>(static_cast<double>(frames_remaining) / processing_rate);
                 time_remaining = std::max<int>(time_remaining, 0);