diff --git a/data/Filter.otio b/data/Filter.otio
index c91c600..027a970 100644
--- a/data/Filter.otio
+++ b/data/Filter.otio
@@ -201,7 +201,7 @@
                                 "OTIO_SCHEMA": "Effect.1",
                                 "effect_name": "toucan:Blur",
                                 "metadata": {
-                                    "radius": 50.0
+                                    "radius": 10.0
                                 }
                             }
                         ],
@@ -245,7 +245,7 @@
                                 "effect_name": "toucan:UnsharpMask",
                                 "metadata": {
                                     "kernel": "gaussian",
-                                    "width": 50.0,
+                                    "width": 10.0,
                                     "contrast": 1.0,
                                     "threshold": 0.0
                                 }
diff --git a/data/MissingMedia.otio b/data/MissingMedia.otio
new file mode 100644
index 0000000..fb30e4a
--- /dev/null
+++ b/data/MissingMedia.otio
@@ -0,0 +1,52 @@
+{
+    "OTIO_SCHEMA": "Timeline.1", 
+    "metadata": {},
+    "name": "Gap",
+    "tracks": {
+        "OTIO_SCHEMA": "Stack.1", 
+        "children": [
+            {
+                "OTIO_SCHEMA": "Track.1", 
+                "children": [
+                    {
+                        "OTIO_SCHEMA": "Clip.1",
+                        "media_reference": {
+                            "OTIO_SCHEMA": "ExternalReference.1",
+                            "available_range": {
+                                "OTIO_SCHEMA": "TimeRange.1",
+                                "duration": {
+                                    "OTIO_SCHEMA": "RationalTime.1",
+                                    "rate": 24,
+                                    "value": 3
+                                },
+                                "start_time": {
+                                    "OTIO_SCHEMA": "RationalTime.1",
+                                    "rate": 24,
+                                    "value": 0
+                                }
+                            },
+                            "target_url": "Letter_None.png"
+                        },
+                        "source_range": {
+                            "OTIO_SCHEMA": "TimeRange.1",
+                            "duration": {
+                                "OTIO_SCHEMA": "RationalTime.1",
+                                "rate": 24,
+                                "value": 3
+                            },
+                            "start_time": {
+                                "OTIO_SCHEMA": "RationalTime.1",
+                                "rate": 24,
+                                "value": 0
+                            }
+                        },
+                        "name": "Letter_None"
+                    }
+                ],
+                "kind": "Video", 
+                "name": "Video"
+            }
+        ], 
+        "name": "Stack"
+    }
+}
diff --git a/data/MissingMedia2.otio b/data/MissingMedia2.otio
new file mode 100644
index 0000000..0d0d44c
--- /dev/null
+++ b/data/MissingMedia2.otio
@@ -0,0 +1,86 @@
+{
+    "OTIO_SCHEMA": "Timeline.1", 
+    "metadata": {},
+    "name": "Gap",
+    "tracks": {
+        "OTIO_SCHEMA": "Stack.1", 
+        "children": [
+            {
+                "OTIO_SCHEMA": "Track.1", 
+                "children": [
+                    {
+                        "OTIO_SCHEMA": "Clip.1",
+                        "media_reference": {
+                            "OTIO_SCHEMA": "ExternalReference.1",
+                            "available_range": {
+                                "OTIO_SCHEMA": "TimeRange.1",
+                                "duration": {
+                                    "OTIO_SCHEMA": "RationalTime.1",
+                                    "rate": 24,
+                                    "value": 3
+                                },
+                                "start_time": {
+                                    "OTIO_SCHEMA": "RationalTime.1",
+                                    "rate": 24,
+                                    "value": 0
+                                }
+                            },
+                            "target_url": "Letter_A.png"
+                        },
+                        "source_range": {
+                            "OTIO_SCHEMA": "TimeRange.1",
+                            "duration": {
+                                "OTIO_SCHEMA": "RationalTime.1",
+                                "rate": 24,
+                                "value": 3
+                            },
+                            "start_time": {
+                                "OTIO_SCHEMA": "RationalTime.1",
+                                "rate": 24,
+                                "value": 0
+                            }
+                        },
+                        "name": "Letter_A"
+                    },
+                    {
+                        "OTIO_SCHEMA": "Clip.1",
+                        "media_reference": {
+                            "OTIO_SCHEMA": "ExternalReference.1",
+                            "available_range": {
+                                "OTIO_SCHEMA": "TimeRange.1",
+                                "duration": {
+                                    "OTIO_SCHEMA": "RationalTime.1",
+                                    "rate": 24,
+                                    "value": 3
+                                },
+                                "start_time": {
+                                    "OTIO_SCHEMA": "RationalTime.1",
+                                    "rate": 24,
+                                    "value": 0
+                                }
+                            },
+                            "target_url": "Letter_None.png"
+                        },
+                        "source_range": {
+                            "OTIO_SCHEMA": "TimeRange.1",
+                            "duration": {
+                                "OTIO_SCHEMA": "RationalTime.1",
+                                "rate": 24,
+                                "value": 3
+                            },
+                            "start_time": {
+                                "OTIO_SCHEMA": "RationalTime.1",
+                                "rate": 24,
+                                "value": 0
+                            }
+                        },
+                        "name": "Letter_None"
+                    }
+                ],
+                "kind": "Video", 
+                "name": "Video"
+            }
+        ], 
+        "name": "Stack"
+    }
+}
diff --git a/lib/toucan/FFmpeg.cpp b/lib/toucan/FFmpeg.cpp
index 0fb1498..1f6e5bc 100644
--- a/lib/toucan/FFmpeg.cpp
+++ b/lib/toucan/FFmpeg.cpp
@@ -25,7 +25,7 @@ namespace toucan
 
         std::vector<std::string> getVideoExtensions()
         {
-            return std::vector<std::string>({ ".mov", ".mp4", ".m4v" });
+            return std::vector<std::string>({ ".mov", ".mp4", ".m4v", ".y4m" });
         }
 
         bool hasVideoExtension(const std::string& value)
diff --git a/lib/toucan/FFmpegWrite.cpp b/lib/toucan/FFmpegWrite.cpp
index 2fa9da9..42bacc6 100644
--- a/lib/toucan/FFmpegWrite.cpp
+++ b/lib/toucan/FFmpegWrite.cpp
@@ -5,6 +5,8 @@
 
 #include "Util.h"
 
+#include <OpenImageIO/imagebufalgo.h>
+
 #include <iostream>
 #include <sstream>
 
@@ -173,7 +175,30 @@ namespace toucan
 
         void Write::writeImage(const OIIO::ImageBuf& buf, const OTIO_NS::RationalTime& time)
         {
-            const auto& spec = buf.spec();
+            auto spec = buf.spec();
+            const OIIO::ImageBuf* bufP = &buf;
+            OIIO::ImageBuf tmp;
+            switch (spec.format.basetype)
+            {
+            case OIIO::TypeDesc::INT8:
+                spec.format.basetype = OIIO::TypeDesc::UINT8;
+                break;
+            case OIIO::TypeDesc::INT16:
+            case OIIO::TypeDesc::UINT32:
+            case OIIO::TypeDesc::INT32:
+            case OIIO::TypeDesc::UINT64:
+            case OIIO::TypeDesc::INT64:
+            case OIIO::TypeDesc::HALF:
+            case OIIO::TypeDesc::FLOAT:
+                spec.format.basetype = OIIO::TypeDesc::UINT16;
+                break;
+            }
+            if (buf.spec().format.basetype != spec.format.basetype)
+            {
+                tmp = OIIO::ImageBufAlgo::copy(buf, spec.format);
+                bufP = &tmp;
+            }
+
             AVPixelFormat avPixelFormatIn = AV_PIX_FMT_NONE;
             switch (spec.nchannels)
             {
@@ -251,7 +276,7 @@ namespace toucan
             av_image_fill_arrays(
                 _avFrame2->data,
                 _avFrame2->linesize,
-                reinterpret_cast<const uint8_t*>(buf.localpixels()),
+                reinterpret_cast<const uint8_t*>(bufP->localpixels()),
                 _avPixelFormatIn,
                 spec.width,
                 spec.height,
diff --git a/lib/toucan/ImageGraph.cpp b/lib/toucan/ImageGraph.cpp
index 23cea0d..44b7b8c 100644
--- a/lib/toucan/ImageGraph.cpp
+++ b/lib/toucan/ImageGraph.cpp
@@ -53,38 +53,64 @@ namespace toucan
         {
             if (auto externalRef = dynamic_cast<OTIO_NS::ExternalReference*>(clip->media_reference()))
             {
-                auto read = std::make_shared<ReadNode>(
-                    _timelineWrapper->getMediaPath(externalRef->target_url()),
-                    _timelineWrapper->getMemoryReference(externalRef->target_url()));
-                const auto& spec = read->getSpec();
-                if (spec.width > 0)
+                try
                 {
-                    _imageSize.x = spec.width;
-                    _imageSize.y = spec.height;
-                    _imageChannels = spec.nchannels;
-                    _imageDataType = toImageDataType(spec.format);
-                    break;
+                    auto read = std::make_shared<ReadNode>(
+                        _timelineWrapper->getMediaPath(externalRef->target_url()),
+                        _timelineWrapper->getMemoryReference(externalRef->target_url()));
+                    const auto& spec = read->getSpec();
+                    if (spec.width > 0)
+                    {
+                        _imageSize.x = spec.width;
+                        _imageSize.y = spec.height;
+                        _imageChannels = spec.nchannels;
+                        _imageDataType = toImageDataType(spec.format);
+                        break;
+                    }
+                }
+                catch (const std::exception& e)
+                {
+                    if (_options.log)
+                    {
+                        _options.log->log(
+                            "ImageGraph",
+                            e.what(),
+                            MessageLogType::Error);
+                    }
                 }
             }
             else if (auto sequenceRef = dynamic_cast<OTIO_NS::ImageSequenceReference*>(clip->media_reference()))
             {
-                auto read = std::make_shared<SequenceReadNode>(
-                    _timelineWrapper->getMediaPath(sequenceRef->target_url_base()),
-                    sequenceRef->name_prefix(),
-                    sequenceRef->name_suffix(),
-                    sequenceRef->start_frame(),
-                    sequenceRef->frame_step(),
-                    sequenceRef->rate(),
-                    sequenceRef->frame_zero_padding(),
-                    _timelineWrapper->getMemoryReferences());
-                const auto& spec = read->getSpec();
-                if (spec.width > 0)
+                try
                 {
-                    _imageSize.x = spec.width;
-                    _imageSize.y = spec.height;
-                    _imageChannels = spec.nchannels;
-                    _imageDataType = toImageDataType(spec.format);
-                    break;
+                    auto read = std::make_shared<SequenceReadNode>(
+                        _timelineWrapper->getMediaPath(sequenceRef->target_url_base()),
+                        sequenceRef->name_prefix(),
+                        sequenceRef->name_suffix(),
+                        sequenceRef->start_frame(),
+                        sequenceRef->frame_step(),
+                        sequenceRef->rate(),
+                        sequenceRef->frame_zero_padding(),
+                        _timelineWrapper->getMemoryReferences());
+                    const auto& spec = read->getSpec();
+                    if (spec.width > 0)
+                    {
+                        _imageSize.x = spec.width;
+                        _imageSize.y = spec.height;
+                        _imageChannels = spec.nchannels;
+                        _imageDataType = toImageDataType(spec.format);
+                        break;
+                    }
+                }
+                catch (const std::exception& e)
+                {
+                    if (_options.log)
+                    {
+                        _options.log->log(
+                            "ImageGraph",
+                            e.what(),
+                            MessageLogType::Error);
+                    }
                 }
             }
             else if (auto generatorRef = dynamic_cast<OTIO_NS::GeneratorReference*>(clip->media_reference()))
@@ -143,7 +169,7 @@ namespace toucan
 
                     // Get the track effects.
                     const auto& effects = track->effects();
-                    if (!effects.empty())
+                    if (trackNode && !effects.empty())
                     {
                         trackNode = _effects(host, effects, trackNode);
                     }
@@ -226,7 +252,7 @@ namespace toucan
         }
 
         // Handle transitions.
-        if (item)
+        if (item && out)
         {
             if (auto prevTransition = OTIO_NS::dynamic_retainer_cast<OTIO_NS::Transition>(prev))
             {
@@ -323,34 +349,65 @@ namespace toucan
                 std::shared_ptr<ReadNode> read;
                 if (!_loadCache.get(externalRef, read))
                 {
-                    read = std::make_shared<ReadNode>(
-                        _timelineWrapper->getMediaPath(externalRef->target_url()),
-                        _timelineWrapper->getMemoryReference(externalRef->target_url()));
+                    try
+                    {
+                        read = std::make_shared<ReadNode>(
+                            _timelineWrapper->getMediaPath(externalRef->target_url()),
+                            _timelineWrapper->getMemoryReference(externalRef->target_url()));
+                    }
+                    catch (const std::exception& e)
+                    {
+                        if (_options.log)
+                        {
+                            _options.log->log(
+                                "ImageGraph",
+                                e.what(),
+                                MessageLogType::Error);
+                        }
+                    }
                     _loadCache.add(externalRef, read);
                 }
-                out = read;
 
                 //! \bug Workaround for when the available range does not match
                 //! the range in the media.
-                const OTIO_NS::TimeRange& timeRange = read->getTimeRange();
-                const auto availableOpt = externalRef->available_range();
-                if (availableOpt.has_value() &&
-                    !availableOpt.value().start_time().strictly_equal(timeRange.start_time()))
+                if (read)
                 {
-                    timeOffset += availableOpt.value().start_time() - timeRange.start_time();
+                    const OTIO_NS::TimeRange& timeRange = read->getTimeRange();
+                    const auto availableOpt = externalRef->available_range();
+                    if (availableOpt.has_value() &&
+                        !availableOpt.value().start_time().strictly_equal(timeRange.start_time()))
+                    {
+                        timeOffset += availableOpt.value().start_time() - timeRange.start_time();
+                    }
                 }
+
+                out = read;
             }
             else if (auto sequenceRef = dynamic_cast<OTIO_NS::ImageSequenceReference*>(clip->media_reference()))
             {
-                auto read = std::make_shared<SequenceReadNode>(
-                    _timelineWrapper->getMediaPath(sequenceRef->target_url_base()),
-                    sequenceRef->name_prefix(),
-                    sequenceRef->name_suffix(),
-                    sequenceRef->start_frame(),
-                    sequenceRef->frame_step(),
-                    sequenceRef->rate(),
-                    sequenceRef->frame_zero_padding(),
-                    _timelineWrapper->getMemoryReferences());
+                std::shared_ptr<SequenceReadNode> read;
+                try
+                {
+                    read = std::make_shared<SequenceReadNode>(
+                        _timelineWrapper->getMediaPath(sequenceRef->target_url_base()),
+                        sequenceRef->name_prefix(),
+                        sequenceRef->name_suffix(),
+                        sequenceRef->start_frame(),
+                        sequenceRef->frame_step(),
+                        sequenceRef->rate(),
+                        sequenceRef->frame_zero_padding(),
+                        _timelineWrapper->getMemoryReferences());
+                }
+                catch (const std::exception& e)
+                {
+                    if (_options.log)
+                    {
+                        _options.log->log(
+                            "ImageGraph",
+                            e.what(),
+                            MessageLogType::Error);
+                    }
+                }
                 out = read;
             }
             else if (auto generatorRef = dynamic_cast<OTIO_NS::GeneratorReference*>(clip->media_reference()))
@@ -367,7 +424,7 @@ namespace toucan
 
         // Get the effects.
         const auto& effects = item->effects();
-        if (!effects.empty())
+        if (out && !effects.empty())
         {
             out = _effects(host, effects, out);
         }
diff --git a/lib/toucan/MessageLog.cpp b/lib/toucan/MessageLog.cpp
index 4334138..4995e5f 100644
--- a/lib/toucan/MessageLog.cpp
+++ b/lib/toucan/MessageLog.cpp
@@ -12,6 +12,7 @@ namespace toucan
         const std::string& message,
         MessageLogType type)
     {
+        std::unique_lock<std::mutex> lock(_mutex);
         switch (type)
         {
         case MessageLogType::Info:
diff --git a/lib/toucan/MessageLog.h b/lib/toucan/MessageLog.h
index 394f992..3e867f1 100644
--- a/lib/toucan/MessageLog.h
+++ b/lib/toucan/MessageLog.h
@@ -4,6 +4,7 @@
 #pragma once
 
 #include <memory>
+#include <mutex>
 #include <string>
 
 namespace toucan
@@ -24,5 +25,8 @@ namespace toucan
             const std::string& prefix,
             const std::string& message,
             MessageLogType = MessageLogType::Info);
+
+    private:
+        std::mutex _mutex;
     };
 }
diff --git a/lib/toucan/Read.cpp b/lib/toucan/Read.cpp
index 440b73b..7df5b71 100644
--- a/lib/toucan/Read.cpp
+++ b/lib/toucan/Read.cpp
@@ -19,22 +19,23 @@ namespace toucan
         _path(path),
         _memoryReader(getMemoryReader(memoryReference))
     {
-        // Open the file ane get information.
-        try
+        // Open the file and get information.
+        if (ffmpeg::hasVideoExtension(path.extension().string()))
         {
             _ffRead = std::make_unique<ffmpeg::Read>(path, memoryReference);
             _spec = _ffRead->getSpec();
             _timeRange = _ffRead->getTimeRange();
         }
-        catch (const std::exception&)
-        {}
-        if (!_ffRead)
+        else
         {
             _input = OIIO::ImageInput::open(_path.string(), nullptr, _memoryReader.get());
-            if (_input)
+            if (!_input)
             {
-                _spec = _input->spec();
+                std::stringstream ss;
+                ss << "Cannot open file: " << _path.string();
+                throw std::runtime_error(ss.str());
             }
+            _spec = _input->spec();
         }
     }
 
diff --git a/lib/toucanView/App.cpp b/lib/toucanView/App.cpp
index b37f198..35a5538 100644
--- a/lib/toucanView/App.cpp
+++ b/lib/toucanView/App.cpp
@@ -68,20 +68,12 @@ namespace toucan
             "toucan-view",
             dtk::Size2I(1920, 1080));
         addWindow(_window);
+        _window->show();
 
         if (!_path.empty())
         {
-            try
-            {
-                _filesModel->open(_path);
-            }
-            catch (const std::exception& e)
-            {
-                _context->getSystem<dtk::DialogSystem>()->message("ERROR", e.what(), _window);
-            }
+            open(_path);
         }
-
-        _window->show();
     }
 
     App::~App()
@@ -115,4 +107,19 @@ namespace toucan
     {
         return _windowModel;
     }
+
+    void App::open(const std::filesystem::path& path)
+    {
+        try
+        {
+            _filesModel->open(path);
+        }
+        catch (const std::exception& e)
+        {
+            _context->getSystem<dtk::DialogSystem>()->message(
+                "ERROR",
+                e.what(),
+                _window);
+        }
+    }
 }
diff --git a/lib/toucanView/App.h b/lib/toucanView/App.h
index a73cd84..3cd3655 100644
--- a/lib/toucanView/App.h
+++ b/lib/toucanView/App.h
@@ -5,6 +5,8 @@
 
 #include <dtk/ui/App.h>
 
+#include <filesystem>
+
 namespace toucan
 {
     class FilesModel;
@@ -42,6 +44,9 @@ namespace toucan
         //! Get the window model.
         const std::shared_ptr<WindowModel>& getWindowModel() const;
 
+        //! Open a file.
+        void open(const std::filesystem::path&);
+
     private:
         std::shared_ptr<MessageLog> _messageLog;
         std::string _path;
diff --git a/lib/toucanView/ExportTool.cpp b/lib/toucanView/ExportTool.cpp
index ab7fd02..fa75c2a 100644
--- a/lib/toucanView/ExportTool.cpp
+++ b/lib/toucanView/ExportTool.cpp
@@ -216,43 +216,19 @@ namespace toucan
         _exportSequenceButton->setClickedCallback(
             [this]
             {
-                _timeRange = _file->getPlaybackModel()->getInOutRange();
-                _export();
+                _export(ExportType::Sequence);
             });
 
         _exportStillButton->setClickedCallback(
             [this]
             {
-                _timeRange = OTIO_NS::TimeRange(
-                    _file->getPlaybackModel()->getCurrentTime(),
-                    OTIO_NS::RationalTime(1.0, _file->getPlaybackModel()->getTimeRange().duration().rate()));
-                _export();
+                _export(ExportType::Still);
             });
 
         _exportMovieButton->setClickedCallback(
             [this]
             {
-                _timeRange = _file->getPlaybackModel()->getInOutRange();
-                const std::string baseName = _movieBaseNameEdit->getText();
-                const std::string extension = _movieExtensionEdit->getText();
-                const std::filesystem::path path = _outputPathEdit->getPath() / (baseName + extension);
-                const IMATH_NAMESPACE::V2d imageSize = _graph->getImageSize();
-                ffmpeg::VideoCodec videoCodec = ffmpeg::VideoCodec::First;
-                ffmpeg::fromString(_movieCodecs[_movieCodecComboBox->getCurrentIndex()], videoCodec);
-                try
-                {
-                    _ffWrite = std::make_shared<ffmpeg::Write>(
-                        path,
-                        OIIO::ImageSpec(imageSize.x, imageSize.y, 3),
-                        _timeRange,
-                        videoCodec);
-                    _export();
-                }
-                catch (const std::exception& e)
-                {
-                    auto dialogSystem = getContext()->getSystem<dtk::DialogSystem>();
-                    dialogSystem->message("ERROR", e.what(), getWindow());
-                }
+                _export(ExportType::Movie);
             });
 
         _timer = dtk::Timer::create(context);
@@ -263,18 +239,6 @@ namespace toucan
             [this](const std::shared_ptr<File>& file)
             {
                 _file = file;
-                if (_file)
-                {
-                    _graph = std::make_shared<ImageGraph>(
-                        _file->getPath(),
-                        _file->getTimelineWrapper());
-                }
-                else
-                {
-                    _timeRange = OTIO_NS::TimeRange();
-                    _time = OTIO_NS::RationalTime();
-                    _graph.reset();
-                }
                 _exportSequenceButton->setEnabled(_file.get());
                 _exportStillButton->setEnabled(_file.get());
                 _exportMovieButton->setEnabled(_file.get());
@@ -320,9 +284,51 @@ namespace toucan
         _setSizeHint(_layout->getSizeHint());
     }
 
-    void ExportWidget::_export()
+    void ExportWidget::_export(ExportType type)
     {
-        _time = _timeRange.start_time();
+        if (!_file)
+            return;
+
+        _graph = std::make_shared<ImageGraph>(
+            _file->getPath(),
+            _file->getTimelineWrapper());
+        _imageSize = _graph->getImageSize();
+
+        switch (type)
+        {
+        case ExportType::Sequence:
+            _timeRange = _file->getPlaybackModel()->getInOutRange();
+            break;
+        case ExportType::Still:
+            _timeRange = OTIO_NS::TimeRange(
+                _file->getPlaybackModel()->getCurrentTime(),
+                OTIO_NS::RationalTime(1.0, _file->getPlaybackModel()->getTimeRange().duration().rate()));
+            break;
+        case ExportType::Movie:
+        {
+            _timeRange = _file->getPlaybackModel()->getInOutRange();
+            const std::string baseName = _movieBaseNameEdit->getText();
+            const std::string extension = _movieExtensionEdit->getText();
+            const std::filesystem::path path = _outputPathEdit->getPath() / (baseName + extension);
+            ffmpeg::VideoCodec videoCodec = ffmpeg::VideoCodec::First;
+            ffmpeg::fromString(_movieCodecs[_movieCodecComboBox->getCurrentIndex()], videoCodec);
+            try
+            {
+                _ffWrite = std::make_shared<ffmpeg::Write>(
+                    path,
+                    OIIO::ImageSpec(_imageSize.x, _imageSize.y, 3),
+                    _timeRange,
+                    videoCodec);
+            }
+            catch (const std::exception& e)
+            {
+                auto dialogSystem = getContext()->getSystem<dtk::DialogSystem>();
+                dialogSystem->message("ERROR", e.what(), getWindow());
+            }
+            break;
+        }
+        default: break;
+        }
 
         _dialog = dtk::ProgressDialog::create(
             getContext(),
@@ -333,64 +339,73 @@ namespace toucan
             [this]
             {
                 _timer->stop();
+                _graph.reset();
                 _ffWrite.reset();
                 _dialog.reset();
             });
         _dialog->show();
 
+        _time = _timeRange.start_time();
         _timer->start(
             std::chrono::microseconds(0),
             [this]
             {
-                if (auto node = _graph->exec(_host, _time))
+                _exportFrame();
+            });
+    }
+
+    void ExportWidget::_exportFrame()
+    {
+        if (auto node = _graph->exec(_host, _time))
+        {
+            const auto buf = node->exec();
+            try
+            {
+                if (_ffWrite)
                 {
-                    const auto buf = node->exec();
-                    if (_ffWrite)
-                    {
-                        try
-                        {
-                            _ffWrite->writeImage(buf, _time);
-                        }
-                        catch (const std::exception& e)
-                        {
-                            if (_dialog)
-                            {
-                                _dialog->close();
-                            }
-                            auto dialogSystem = getContext()->getSystem<dtk::DialogSystem>();
-                            dialogSystem->message("ERROR", e.what(), getWindow());
-                        }
-                    }
-                    else
-                    {
-                        const std::string fileName = getSequenceFrame(
-                            _outputPathEdit->getPath().string(),
-                            _imageBaseNameEdit->getText(),
-                            _time.to_frames(),
-                            _imagePaddingEdit->getValue(),
-                            _imageExtensionEdit->getText());
-                        buf.write(fileName);
-                    }
+                    _ffWrite->writeImage(buf, _time);
                 }
-
+                else
+                {
+                    const std::string fileName = getSequenceFrame(
+                        _outputPathEdit->getPath().string(),
+                        _imageBaseNameEdit->getText(),
+                        _time.to_frames(),
+                        _imagePaddingEdit->getValue(),
+                        _imageExtensionEdit->getText());
+                    buf.write(fileName);
+                }
+            }
+            catch (const std::exception& e)
+            {
                 if (_dialog)
                 {
-                    const OTIO_NS::RationalTime end = _timeRange.end_time_inclusive();
-                    if (_time < end)
-                    {
-                        _time += OTIO_NS::RationalTime(1.0, _timeRange.duration().rate());
-                        const OTIO_NS::RationalTime duration = _timeRange.duration();
-                        const double v = duration.value() > 0.0 ?
-                            (_time - _timeRange.start_time()).value() / static_cast<double>(duration.value()) :
-                            0.0;
-                        _dialog->setValue(v);
-                    }
-                    else
-                    {
-                        _dialog->close();
-                    }
+                    _dialog->close();
                 }
-            });
+                getContext()->getSystem<dtk::DialogSystem>()->message(
+                    "ERROR",
+                    e.what(),
+                    getWindow());
+            }
+        }
+
+        if (_dialog)
+        {
+            const OTIO_NS::RationalTime end = _timeRange.end_time_inclusive();
+            if (_time < end)
+            {
+                _time += OTIO_NS::RationalTime(1.0, _timeRange.duration().rate());
+                const OTIO_NS::RationalTime duration = _timeRange.duration();
+                const double v = duration.value() > 0.0 ?
+                    (_time - _timeRange.start_time()).value() / static_cast<double>(duration.value()) :
+                    0.0;
+                _dialog->setValue(v);
+            }
+            else
+            {
+                _dialog->close();
+            }
+        }
     }
 
     void ExportWidget::_widgetUpdate()
diff --git a/lib/toucanView/ExportTool.h b/lib/toucanView/ExportTool.h
index 1d5dd08..ac80c80 100644
--- a/lib/toucanView/ExportTool.h
+++ b/lib/toucanView/ExportTool.h
@@ -47,7 +47,16 @@ namespace toucan
         void sizeHintEvent(const dtk::SizeHintEvent&) override;
 
     private:
-        void _export();
+        enum class ExportType
+        {
+            Sequence,
+            Still,
+            Movie
+        };
+
+        void _export(ExportType);
+        void _exportFrame();
+
         void _widgetUpdate();
 
         std::shared_ptr<ImageEffectHost> _host;
@@ -55,6 +64,7 @@ namespace toucan
         OTIO_NS::TimeRange _timeRange;
         OTIO_NS::RationalTime _time;
         std::shared_ptr<ImageGraph> _graph;
+        IMATH_NAMESPACE::V2d _imageSize = IMATH_NAMESPACE::V2d(0, 0);
         std::vector<std::string> _movieCodecs;
         std::shared_ptr<ffmpeg::Write> _ffWrite;
 
diff --git a/lib/toucanView/FilesModel.cpp b/lib/toucanView/FilesModel.cpp
index f815b01..65914e2 100644
--- a/lib/toucanView/FilesModel.cpp
+++ b/lib/toucanView/FilesModel.cpp
@@ -30,8 +30,8 @@ namespace toucan
     {
         if (auto context = _context.lock())
         {
-            auto files = _files->get();
             auto file = std::make_shared<File>(context, _host, path);
+            auto files = _files->get();
             files.push_back(file);
             _files->setIfChanged(files);
             const int index = files.size() - 1;
diff --git a/lib/toucanView/MenuBar.cpp b/lib/toucanView/MenuBar.cpp
index 1f2bee4..08dbd78 100644
--- a/lib/toucanView/MenuBar.cpp
+++ b/lib/toucanView/MenuBar.cpp
@@ -12,9 +12,7 @@
 #include <toucan/TimelineAlgo.h>
 
 #include <dtk/ui/Action.h>
-#include <dtk/ui/DialogSystem.h>
 #include <dtk/ui/FileBrowser.h>
-#include <dtk/ui/MessageDialog.h>
 #include <dtk/ui/RecentFilesModel.h>
 #include <dtk/core/Format.h>
 
@@ -94,7 +92,7 @@ namespace toucan
                         file.string(),
                         [this, file]
                         {
-                            _filesModel->open(file);
+                            _app.lock()->open(file);
                             _menus["File"]->close();
                         });
                     _menus["RecentFiles"]->addItem(item);
@@ -155,17 +153,7 @@ namespace toucan
                             getWindow(),
                             [this](const std::filesystem::path& path)
                             {
-                                if (auto context = getContext())
-                                {
-                                    try
-                                    {
-                                        _filesModel->open(path);
-                                    }
-                                    catch (const std::exception& e)
-                                    {
-                                        context->getSystem<dtk::DialogSystem>()->message("ERROR", e.what(), getWindow());
-                                    }
-                                }
+                                _app.lock()->open(path);
                             },
                             _filesModel->getRecentFilesModel());
                     }
diff --git a/lib/toucanView/ThumbnailGenerator.cpp b/lib/toucanView/ThumbnailGenerator.cpp
index fcaa43d..34cdb26 100644
--- a/lib/toucanView/ThumbnailGenerator.cpp
+++ b/lib/toucanView/ThumbnailGenerator.cpp
@@ -7,27 +7,40 @@
 
 #include <OpenImageIO/imagebufalgo.h>
 
-#include <sstream>
-
 namespace toucan
 {
     ThumbnailGenerator::ThumbnailGenerator(
         const std::filesystem::path& path,
         const std::shared_ptr<TimelineWrapper>& timelineWrapper,
-        const std::shared_ptr<ImageEffectHost>& host) :
+        const std::shared_ptr<ImageEffectHost>& host,
+        const std::shared_ptr<MessageLog>& log) :
         _path(path),
         _timelineWrapper(timelineWrapper),
-        _host(host)
+        _host(host),
+        _log(log)
     {
         _thread.running = true;
         _thread.thread = std::thread(
             [this]
             {
-                _graph = std::make_shared<ImageGraph>(_path, _timelineWrapper);
-                const IMATH_NAMESPACE::V2i& imageSize = _graph->getImageSize();
-                _aspect = imageSize.y > 0 ?
-                    (imageSize.x / static_cast<float>(imageSize.y)) :
-                    0.F;
+                try
+                {
+                    _graph = std::make_shared<ImageGraph>(_path, _timelineWrapper);
+                    const IMATH_NAMESPACE::V2i& imageSize = _graph->getImageSize();
+                    _aspect = imageSize.y > 0 ?
+                        (imageSize.x / static_cast<float>(imageSize.y)) :
+                        0.F;
+                }
+                catch (const std::exception& e)
+                {
+                    if (_log)
+                    {
+                        _log->log(
+                            "ThumbnailGenerator",
+                            e.what(),
+                            MessageLogType::Error);
+                    }
+                }
 
                 while (_thread.running)
                 {
@@ -134,72 +147,85 @@ namespace toucan
             {
                 thumbnail = i->second;
             }
-            else
+            else if (_graph)
             {
-                auto graph = _graph->exec(_host, request->time);
-                const auto sourceBuf = graph->exec();
-                const auto& sourceSpec = sourceBuf.spec();
-
-                const dtk::Size2I thumbnailSize(request->height * _aspect, request->height);
-                dtk::ImageInfo info;
-                info.size = thumbnailSize;
-                switch (sourceSpec.nchannels)
+                try
                 {
-                case 1:
-                    switch (sourceSpec.format.basetype)
+                    auto graph = _graph->exec(_host, request->time);
+                    const auto sourceBuf = graph->exec();
+                    const auto& sourceSpec = sourceBuf.spec();
+
+                    const dtk::Size2I thumbnailSize(request->height * _aspect, request->height);
+                    dtk::ImageInfo info;
+                    info.size = thumbnailSize;
+                    switch (sourceSpec.nchannels)
                     {
-                    case OIIO::TypeDesc::UINT8: info.type = dtk::ImageType::L_U8; break;
-                    case OIIO::TypeDesc::UINT16: info.type = dtk::ImageType::L_U16; break;
-                    case OIIO::TypeDesc::HALF: info.type = dtk::ImageType::L_F16; break;
-                    case OIIO::TypeDesc::FLOAT: info.type = dtk::ImageType::L_F32; break;
+                    case 1:
+                        switch (sourceSpec.format.basetype)
+                        {
+                        case OIIO::TypeDesc::UINT8: info.type = dtk::ImageType::L_U8; break;
+                        case OIIO::TypeDesc::UINT16: info.type = dtk::ImageType::L_U16; break;
+                        case OIIO::TypeDesc::HALF: info.type = dtk::ImageType::L_F16; break;
+                        case OIIO::TypeDesc::FLOAT: info.type = dtk::ImageType::L_F32; break;
+                        }
+                        break;
+                    case 2:
+                        switch (sourceSpec.format.basetype)
+                        {
+                        case OIIO::TypeDesc::UINT8: info.type = dtk::ImageType::LA_U8; break;
+                        case OIIO::TypeDesc::UINT16: info.type = dtk::ImageType::LA_U16; break;
+                        case OIIO::TypeDesc::HALF: info.type = dtk::ImageType::LA_F16; break;
+                        case OIIO::TypeDesc::FLOAT: info.type = dtk::ImageType::LA_F32; break;
+                        }
+                        break;
+                    case 3:
+                        switch (sourceSpec.format.basetype)
+                        {
+                        case OIIO::TypeDesc::UINT8: info.type = dtk::ImageType::RGB_U8; break;
+                        case OIIO::TypeDesc::UINT16: info.type = dtk::ImageType::RGB_U16; break;
+                        case OIIO::TypeDesc::HALF: info.type = dtk::ImageType::RGB_F16; break;
+                        case OIIO::TypeDesc::FLOAT: info.type = dtk::ImageType::RGB_F32; break;
+                        }
+                        break;
+                    default:
+                        switch (sourceSpec.format.basetype)
+                        {
+                        case OIIO::TypeDesc::UINT8: info.type = dtk::ImageType::RGBA_U8; break;
+                        case OIIO::TypeDesc::UINT16: info.type = dtk::ImageType::RGBA_U16; break;
+                        case OIIO::TypeDesc::HALF: info.type = dtk::ImageType::RGBA_F16; break;
+                        case OIIO::TypeDesc::FLOAT: info.type = dtk::ImageType::RGBA_F32; break;
+                        }
+                        break;
                     }
-                    break;
-                case 2:
-                    switch (sourceSpec.format.basetype)
-                    {
-                    case OIIO::TypeDesc::UINT8: info.type = dtk::ImageType::LA_U8; break;
-                    case OIIO::TypeDesc::UINT16: info.type = dtk::ImageType::LA_U16; break;
-                    case OIIO::TypeDesc::HALF: info.type = dtk::ImageType::LA_F16; break;
-                    case OIIO::TypeDesc::FLOAT: info.type = dtk::ImageType::LA_F32; break;
-                    }
-                    break;
-                case 3:
-                    switch (sourceSpec.format.basetype)
-                    {
-                    case OIIO::TypeDesc::UINT8: info.type = dtk::ImageType::RGB_U8; break;
-                    case OIIO::TypeDesc::UINT16: info.type = dtk::ImageType::RGB_U16; break;
-                    case OIIO::TypeDesc::HALF: info.type = dtk::ImageType::RGB_F16; break;
-                    case OIIO::TypeDesc::FLOAT: info.type = dtk::ImageType::RGB_F32; break;
-                    }
-                    break;
-                default:
-                    switch (sourceSpec.format.basetype)
+                    info.layout.mirror.y = true;
+
+                    if (info.isValid())
                     {
-                    case OIIO::TypeDesc::UINT8: info.type = dtk::ImageType::RGBA_U8; break;
-                    case OIIO::TypeDesc::UINT16: info.type = dtk::ImageType::RGBA_U16; break;
-                    case OIIO::TypeDesc::HALF: info.type = dtk::ImageType::RGBA_F16; break;
-                    case OIIO::TypeDesc::FLOAT: info.type = dtk::ImageType::RGBA_F32; break;
+                        thumbnail = dtk::Image::create(info);
+                        auto resizedBuf = OIIO::ImageBufAlgo::resize(
+                            sourceBuf,
+                            "",
+                            0.F,
+                            OIIO::ROI(
+                                0, info.size.w,
+                                0, info.size.h,
+                                0, 1,
+                                0, std::min(4, sourceSpec.nchannels)));
+                        memcpy(
+                            thumbnail->getData(),
+                            resizedBuf.localpixels(),
+                            thumbnail->getByteCount());
                     }
-                    break;
                 }
-                info.layout.mirror.y = true;
-
-                if (info.isValid())
+                catch (const std::exception& e)
                 {
-                    thumbnail = dtk::Image::create(info);
-                    auto resizedBuf = OIIO::ImageBufAlgo::resize(
-                        sourceBuf,
-                        "",
-                        0.F,
-                        OIIO::ROI(
-                            0, info.size.w,
-                            0, info.size.h,
-                            0, 1,
-                            0, std::min(4, sourceSpec.nchannels)));
-                    memcpy(
-                        thumbnail->getData(),
-                        resizedBuf.localpixels(),
-                        thumbnail->getByteCount());
+                    if (_log)
+                    {
+                        _log->log(
+                            "ThumbnailGenerator",
+                            e.what(),
+                            MessageLogType::Error);
+                    }
                 }
 
                 _thread.cache[std::make_pair(request->time, request->height)] = thumbnail;
diff --git a/lib/toucanView/ThumbnailGenerator.h b/lib/toucanView/ThumbnailGenerator.h
index 91fb092..1068601 100644
--- a/lib/toucanView/ThumbnailGenerator.h
+++ b/lib/toucanView/ThumbnailGenerator.h
@@ -5,6 +5,7 @@
 
 #include <toucan/ImageEffectHost.h>
 #include <toucan/ImageGraph.h>
+#include <toucan/MessageLog.h>
 #include <toucan/TimelineWrapper.h>
 
 #include <dtk/core/Image.h>
@@ -34,7 +35,8 @@ namespace toucan
         ThumbnailGenerator(
             const std::filesystem::path&,
             const std::shared_ptr<TimelineWrapper>&,
-            const std::shared_ptr<ImageEffectHost>&);
+            const std::shared_ptr<ImageEffectHost>&,
+            const std::shared_ptr<MessageLog>& = nullptr);
 
         ~ThumbnailGenerator();
 
@@ -56,6 +58,7 @@ namespace toucan
         std::filesystem::path _path;
         std::shared_ptr<TimelineWrapper> _timelineWrapper;
         std::shared_ptr<ImageEffectHost> _host;
+        std::shared_ptr<MessageLog> _log;
         std::shared_ptr<ImageGraph> _graph;
         float _aspect = 1.F;