diff --git a/firmware/application/CMakeLists.txt b/firmware/application/CMakeLists.txt
index 653b1d5b..4ab4504e 100644
--- a/firmware/application/CMakeLists.txt
+++ b/firmware/application/CMakeLists.txt
@@ -182,6 +182,7 @@ set(CPPSRC
 	io_convert.cpp
 	io_file.cpp
 	io_wave.cpp
+	iq_trim.cpp
 	irq_controls.cpp
 	irq_lcd_frame.cpp
 	irq_rtc.cpp
diff --git a/firmware/application/apps/ui_iq_trim.cpp b/firmware/application/apps/ui_iq_trim.cpp
index 1a9f25df..2da29125 100644
--- a/firmware/application/apps/ui_iq_trim.cpp
+++ b/firmware/application/apps/ui_iq_trim.cpp
@@ -30,41 +30,72 @@ namespace fs = std::filesystem;
 
 namespace ui {
 
-IQTrimView::IQTrimView(NavigationView& nav) {
+IQTrimView::IQTrimView(NavigationView& nav)
+    : nav_{nav} {
     add_children({
         &labels,
         &field_path,
-        &text_range,
+        &field_start,
+        &field_end,
+        &text_samples,
+        &text_max,
+        &field_cutoff,
         &button_trim,
     });
 
-    field_path.on_select = [this, &nav](TextField&) {
-        auto open_view = nav.push<FileLoadView>(".C*");
+    field_path.on_select = [this](TextField&) {
+        auto open_view = nav_.push<FileLoadView>(".C*");
         open_view->push_dir(u"CAPTURES");
         open_view->on_changed = [this](fs::path path) {
-            read_capture(path);
             path_ = std::move(path);
+            profile_capture();
+            compute_range();
             refresh_ui();
         };
     };
 
-    button_trim.on_select = [this, &nav](Button&) {
-        if (!path_.empty() && trim_range_.file_size > 0) {
-            progress_ui.show_trimming();
-            TrimFile(path_, trim_range_);
-            read_capture(path_);
+    text_samples.set_style(&Styles::light_grey);
+    text_max.set_style(&Styles::light_grey);
+
+    field_start.on_change = [this](int32_t v) {
+        if (field_end.value() < v)
+            field_end.set_value(v, false);
+        set_dirty();
+    };
+
+    field_end.on_change = [this](int32_t v) {
+        if (field_start.value() > v)
+            field_start.set_value(v, false);
+        set_dirty();
+    };
+
+    field_cutoff.set_value(7);  // 7% of max is a good default.
+    field_cutoff.on_change = [this](int32_t) {
+        compute_range();
+        refresh_ui();
+    };
+
+    button_trim.on_select = [this](Button&) {
+        if (trim_capture()) {
+            profile_capture();
+            compute_range();
             refresh_ui();
-        } else {
-            nav.display_modal("Error", "Select a file first.");
         }
     };
 }
 
 void IQTrimView::paint(Painter& painter) {
-    if (!path_.empty()) {
+    if (info_) {
+        uint32_t power_cutoff = field_cutoff.value() * static_cast<uint64_t>(info_->max_power) / 100;
+
         // Draw power buckets.
         for (size_t i = 0; i < power_buckets_.size(); ++i) {
-            auto amp = power_buckets_[i].power;
+            auto power = power_buckets_[i].power;
+            uint8_t amp = 0;
+
+            if (power > power_cutoff && info_->max_power > 0)
+                amp = (255ULL * power) / info_->max_power;
+
             painter.draw_vline(
                 pos_lines + Point{(int)i, 0},
                 height_lines,
@@ -72,8 +103,8 @@ void IQTrimView::paint(Painter& painter) {
         }
 
         // Draw trim range edges.
-        int start_x = screen_width * trim_range_.start / trim_range_.file_size;
-        int end_x = screen_width * trim_range_.end / trim_range_.file_size;
+        int start_x = screen_width * field_start.value() / info_->sample_count;
+        int end_x = screen_width * field_end.value() / info_->sample_count;
 
         painter.draw_vline(
             pos_lines + Point{start_x, 0},
@@ -92,27 +123,72 @@ void IQTrimView::focus() {
 
 void IQTrimView::refresh_ui() {
     field_path.set_text(path_.filename().string());
-    text_range.set(to_string_dec_uint(trim_range_.start) + "-" + to_string_dec_uint(trim_range_.end));
+    text_samples.set(to_string_dec_uint(info_->sample_count));
+    text_max.set(to_string_dec_uint(info_->max_power));
     set_dirty();
 }
 
-bool IQTrimView::read_capture(const fs::path& path) {
+void IQTrimView::update_range_controls(iq::TrimRange trim_range) {
+    auto max_range = info_ ? info_->sample_count : 0;
+    auto step = info_ ? info_->sample_count / screen_width : 0;
+
+    field_start.set_range(0, max_range);
+    field_start.set_step(step);
+    field_end.set_range(0, max_range);
+    field_end.set_step(step);
+
+    field_start.set_value(trim_range.start_sample, false);
+    field_end.set_value(trim_range.end_sample, false);
+}
+
+void IQTrimView::profile_capture() {
     power_buckets_ = {};
-    PowerBuckets buckets{
+    iq::PowerBuckets buckets{
         .p = power_buckets_.data(),
         .size = power_buckets_.size()};
 
     progress_ui.show_reading();
-    auto range = ComputeTrimRange(path, amp_threshold, &buckets, progress_ui.get_callback());
+    info_ = iq::profile_capture(path_, buckets);
     progress_ui.clear();
-
-    if (range) {
-        trim_range_ = *range;
-        return true;
-    } else {
-        trim_range_ = {};
-        return false;
-    }
 }
 
-}  // namespace ui
\ No newline at end of file
+void IQTrimView::compute_range() {
+    if (!info_)
+        return;
+
+    iq::PowerBuckets buckets{
+        .p = power_buckets_.data(),
+        .size = power_buckets_.size()};
+    auto trim_range = iq::compute_trim_range(*info_, buckets, field_cutoff.value());
+
+    update_range_controls(trim_range);
+}
+
+bool IQTrimView::trim_capture() {
+    if (!info_) {
+        nav_.display_modal("Error", "Open a file first.");
+        return false;
+    }
+
+    bool trimmed = false;
+    iq::TrimRange trim_range{
+        static_cast<uint32_t>(field_start.value()),
+        static_cast<uint32_t>(field_end.value()),
+        info_->sample_size};
+
+    if (trim_range.start_sample >= trim_range.end_sample) {
+        nav_.display_modal("Error", "Invalid trimming range.");
+        return false;
+    }
+
+    progress_ui.show_trimming();
+    trimmed = iq::trim_capture_with_range(path_, trim_range, progress_ui.get_callback());
+    progress_ui.clear();
+
+    if (!trimmed)
+        nav_.display_modal("Error", "Trimming failed.");
+
+    return trimmed;
+}
+
+}  // namespace ui
diff --git a/firmware/application/apps/ui_iq_trim.hpp b/firmware/application/apps/ui_iq_trim.hpp
index 345ca1da..c3bae915 100644
--- a/firmware/application/apps/ui_iq_trim.hpp
+++ b/firmware/application/apps/ui_iq_trim.hpp
@@ -24,6 +24,7 @@
 
 #include "file.hpp"
 #include "iq_trim.hpp"
+#include "optional.hpp"
 #include "ui.hpp"
 #include "ui_navigation.hpp"
 #include "ui_styles.hpp"
@@ -49,7 +50,7 @@ class TrimProgressUI {
 
     void show_progress(uint8_t percent) {
         auto width = percent * screen_width / 100;
-        p.draw_hline({0, 6 * 16}, width, Color::yellow());
+        p.draw_hline({0, 6 * 16 + 2}, width, Color::yellow());
     }
 
     void clear() {
@@ -73,18 +74,36 @@ class IQTrimView : public View {
     void focus() override;
 
    private:
+    /* Update controls with latest values. */
     void refresh_ui();
-    bool read_capture(const std::filesystem::path& path);
+
+    /* Update the start/end controls with trim range info. */
+    void update_range_controls(iq::TrimRange trim_range);
+
+    /* Collect capture info and samples to draw the UI. */
+    void profile_capture();
+
+    /* Determine the start and end buckets based on the cutoff. */
+    void compute_range();
+
+    /* Trims the capture file based on the settings. */
+    bool trim_capture();
+
+    NavigationView& nav_;
 
     std::filesystem::path path_{};
-    TrimRange trim_range_{};
-    std::array<PowerBuckets::Bucket, screen_width> power_buckets_{};
-    uint8_t amp_threshold = 5;
+    Optional<iq::CaptureInfo> info_{};
+    std::array<iq::PowerBuckets::Bucket, screen_width> power_buckets_{};
     TrimProgressUI progress_ui{};
 
     Labels labels{
         {{0 * 8, 0 * 16}, "Capture File:", Color::light_grey()},
-        {{0 * 8, 6 * 16}, "Range:", Color::light_grey()},
+        {{0 * 8, 6 * 16}, "Start  :", Color::light_grey()},
+        {{0 * 8, 7 * 16}, "End    :", Color::light_grey()},
+        {{0 * 8, 8 * 16}, "Samples:", Color::light_grey()},
+        {{0 * 8, 9 * 16}, "Max Pwr:", Color::light_grey()},
+        {{0 * 8, 10 * 16}, "Cutoff :", Color::light_grey()},
+        {{12 * 8, 10 * 16}, "%", Color::light_grey()},
     };
 
     TextField field_path{
@@ -94,12 +113,37 @@ class IQTrimView : public View {
     Point pos_lines{0 * 8, 4 * 16};
     Dim height_lines{2 * 16};
 
-    Text text_range{
-        {7 * 8, 6 * 16, 20 * 8, 1 * 16},
-        {}};
+    NumberField field_start{
+        {9 * 8, 6 * 16},
+        10,
+        {0, 0},
+        1,
+        ' '};
+
+    NumberField field_end{
+        {9 * 8, 7 * 16},
+        10,
+        {0, 0},
+        1,
+        ' '};
+
+    Text text_samples{
+        {9 * 8, 8 * 16, 10 * 8, 1 * 16},
+        "0"};
+
+    Text text_max{
+        {9 * 8, 9 * 16, 10 * 8, 1 * 16},
+        "0"};
+
+    NumberField field_cutoff{
+        {9 * 8, 10 * 16},
+        3,
+        {1, 100},
+        1,
+        ' '};
 
     Button button_trim{
-        {11 * 8, 9 * 16, 8 * 8, 3 * 16},
+        {20 * 8, 16 * 16, 8 * 8, 2 * 16},
         "Trim"};
 };
 
diff --git a/firmware/application/file.cpp b/firmware/application/file.cpp
index 709f1a46..b22c7133 100644
--- a/firmware/application/file.cpp
+++ b/firmware/application/file.cpp
@@ -279,46 +279,6 @@ std::vector<std::filesystem::path> scan_root_directories(const std::filesystem::
     return directory_list;
 }
 
-std::filesystem::filesystem_error trim_file(const std::filesystem::path& file_path, uint64_t start, uint64_t length) {
-    constexpr size_t buffer_size = std::filesystem::max_file_block_size;
-    uint8_t buffer[buffer_size];
-    auto temp_path = file_path + u"-tmp";
-
-    /* Scope for File instances. */
-    {
-        File src;
-        File dst;
-
-        auto error = src.open(file_path);
-        if (error) return error.value();
-
-        error = dst.create(temp_path);
-        if (error) return error.value();
-
-        src.seek(start);
-        auto remaining = length;
-
-        while (true) {
-            auto result = src.read(buffer, buffer_size);
-            if (result.is_error()) return result.error();
-
-            auto to_write = std::min(remaining, *result);
-
-            result = dst.write(buffer, to_write);
-            if (result.is_error()) return result.error();
-
-            remaining -= *result;
-
-            if (*result < buffer_size || remaining == 0)
-                break;
-        }
-    }
-
-    // Delete original and overwrite with temp file.
-    delete_file(file_path);
-    return rename_file(temp_path, file_path);
-}
-
 std::filesystem::filesystem_error delete_file(const std::filesystem::path& file_path) {
     return {f_unlink(reinterpret_cast<const TCHAR*>(file_path.c_str()))};
 }
diff --git a/firmware/application/file.hpp b/firmware/application/file.hpp
index eb94712b..d8662c9a 100644
--- a/firmware/application/file.hpp
+++ b/firmware/application/file.hpp
@@ -265,7 +265,6 @@ struct FATTimestamp {
     uint16_t FAT_time;
 };
 
-std::filesystem::filesystem_error trim_file(const std::filesystem::path& file_path, uint64_t start, uint64_t length);
 std::filesystem::filesystem_error delete_file(const std::filesystem::path& file_path);
 std::filesystem::filesystem_error rename_file(const std::filesystem::path& file_path, const std::filesystem::path& new_name);
 std::filesystem::filesystem_error copy_file(const std::filesystem::path& file_path, const std::filesystem::path& dest_path);
@@ -302,6 +301,7 @@ static_assert(sizeof(FIL::err) == 1, "FatFs FIL::err size not expected.");
 #define FR_BAD_SEEK (0x102)
 #define FR_UNEXPECTED (0x103)
 
+/* NOTE: sizeof(File) == 556 bytes because of the FIL's buf member. */
 class File {
    public:
     using Size = uint64_t;
diff --git a/firmware/application/iq_trim.cpp b/firmware/application/iq_trim.cpp
new file mode 100644
index 00000000..335f30e0
--- /dev/null
+++ b/firmware/application/iq_trim.cpp
@@ -0,0 +1,195 @@
+/*
+ * Copyright (C) 2023 Kyle Reed
+ *
+ * This file is part of PortaPack.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include "iq_trim.hpp"
+
+#include <memory>
+#include "string_format.hpp"
+
+namespace fs = std::filesystem;
+
+namespace iq {
+
+/* Trimming helpers based on the sample type (complex8 or complex16). */
+template <typename T>
+uint32_t power(T value) {
+    auto real = value.real();
+    auto imag = value.imag();
+    return (real * real) + (imag * imag);
+}
+
+/* Collects capture file metadata and sample power buckets. */
+template <typename T>
+Optional<CaptureInfo> profile_capture(
+    const std::filesystem::path& path,
+    PowerBuckets& buckets,
+    uint8_t samples_per_bucket) {
+    File f;
+    auto error = f.open(path);
+    if (error)
+        return {};
+
+    CaptureInfo info{
+        .file_size = f.size(),
+        .sample_count = f.size() / sizeof(T),
+        .sample_size = sizeof(T),
+        .max_power = 0};
+
+    auto profile_samples = buckets.size * samples_per_bucket;
+    auto sample_interval = info.sample_count / profile_samples;
+    uint32_t bucket_width = std::max(1ULL, info.sample_count / buckets.size);
+    uint64_t sample_index = 0;
+    T value{};
+
+    while (true) {
+        f.seek(sample_index * info.sample_size);
+        auto result = f.read(&value, info.sample_size);
+        if (!result) return {};  // Read failed.
+
+        if (*result != info.sample_size)
+            break;  // EOF
+
+        auto mag_squared = power(value);
+
+        if (mag_squared > info.max_power)
+            info.max_power = mag_squared;
+
+        auto bucket_index = sample_index / bucket_width;
+        buckets.add(bucket_index, mag_squared);
+        sample_index += sample_interval;
+    }
+
+    return info;
+}
+
+Optional<CaptureInfo> profile_capture(
+    const fs::path& path,
+    PowerBuckets& buckets,
+    uint8_t samples_per_bucket) {
+    auto sample_size = fs::capture_file_sample_size(path);
+
+    switch (sample_size) {
+        case sizeof(complex16_t):
+            return profile_capture<complex16_t>(path, buckets, samples_per_bucket);
+
+        case sizeof(complex8_t):
+            return profile_capture<complex8_t>(path, buckets, samples_per_bucket);
+
+        default:
+            return {};
+    };
+}
+
+TrimRange compute_trim_range(
+    CaptureInfo info,
+    const PowerBuckets& buckets,
+    uint8_t cutoff_percent) {
+    bool has_start = false;
+    uint8_t start_bucket = 0;
+    uint8_t end_bucket = 0;
+
+    uint32_t power_cutoff = cutoff_percent * static_cast<uint64_t>(info.max_power) / 100;
+
+    for (size_t i = 0; i < buckets.size; ++i) {
+        auto power = buckets.p[i].power;
+
+        if (power > power_cutoff) {
+            if (has_start)
+                end_bucket = i;
+            else {
+                start_bucket = i;
+                end_bucket = i;
+                has_start = true;
+            }
+        }
+    }
+
+    // End should be the first bucket after the last with signal.
+    // This makes the math downstream simpler. NB: may be > buckets.size.
+    end_bucket++;
+
+    auto samples_per_bucket = info.sample_count / buckets.size;
+    return {
+        start_bucket * samples_per_bucket,
+        end_bucket * samples_per_bucket,
+        info.sample_size};
+}
+
+bool trim_capture_with_range(
+    const fs::path& path,
+    TrimRange range,
+    const std::function<void(uint8_t)>& on_progress) {
+    constexpr size_t buffer_size = std::filesystem::max_file_block_size;
+    uint8_t buffer[buffer_size];
+    auto temp_path = path + u"-tmp";
+
+    // end_sample is the first sample to _not_ include.
+    auto start_byte = range.start_sample * range.sample_size;
+    auto end_byte = (range.end_sample * range.sample_size);
+    auto length = end_byte - start_byte;
+
+    // 'File' is 556 bytes! Heap alloc to avoid overflowing the stack.
+    auto src = std::make_unique<File>();
+    auto dst = std::make_unique<File>();
+
+    auto error = src->open(path);
+    if (error) return false;
+
+    error = dst->create(temp_path);
+    if (error) return false;
+
+    src->seek(start_byte);
+    auto processed = 0UL;
+    auto next_report = 0UL;
+    auto report_interval = length / 20UL;
+
+    while (true) {
+        auto result = src->read(buffer, buffer_size);
+        if (result.is_error()) return false;
+
+        auto remaining = length - processed;
+        auto to_write = std::min(remaining, *result);
+
+        result = dst->write(buffer, to_write);
+        if (result.is_error()) return false;
+
+        processed += *result;
+
+        if (*result < buffer_size || processed >= length)
+            break;
+
+        if (processed >= next_report) {
+            on_progress(100 * processed / length);
+            next_report += report_interval;
+        }
+    }
+
+    // Close files before renaming/deleting.
+    src.reset();
+    dst.reset();
+
+    // Delete original and overwrite with temp file.
+    delete_file(path);
+    rename_file(temp_path, path);
+    return true;
+}
+
+}  // namespace iq
\ No newline at end of file
diff --git a/firmware/application/iq_trim.hpp b/firmware/application/iq_trim.hpp
index cc53f236..a6d1546f 100644
--- a/firmware/application/iq_trim.hpp
+++ b/firmware/application/iq_trim.hpp
@@ -29,146 +29,65 @@
 #include <functional>
 #include <limits>
 
-struct TrimRange {
-    uint64_t start;
-    uint64_t end;
-    uint64_t sample_count;
+namespace iq {
+
+/* Information about a capture. */
+struct CaptureInfo {
     uint64_t file_size;
+    uint64_t sample_count;
     uint8_t sample_size;
+    uint32_t max_power;
 };
 
+/* Holds sample average power by bucket. */
 struct PowerBuckets {
     struct Bucket {
-        uint8_t power;
+        uint32_t power = 0;
+        uint8_t count = 0;
     };
 
     Bucket* p = nullptr;
-    size_t size = 0;
+    const size_t size = 0;
 
-    void add(size_t index) {
-        // This originally was meant to be an average power for the bucket,
-        // but it was a lot of extra math just for a little bit of UI and
-        // the math really slowed down processing. Instead, just count the
-        // number of samples above the threshold.
+    /* Add the power to the bucket average at index. */
+    void add(size_t index, uint32_t power) {
         if (index < size) {
-            if (p[index].power < 255)
-                p[index].power++;
+            auto& b = p[index];
+            auto avg = static_cast<uint64_t>(b.power) * b.count;
+
+            b.count++;
+            b.power = (power + avg) / b.count;
         }
     }
 };
 
-inline bool TrimFile(const std::filesystem::path& path, TrimRange range) {
-    // NB: range.end should be included in the trimmed result, so '+ sample_size'.
-    auto result = trim_file(path, range.start, (range.end - range.start) + range.sample_size);
-    return result.ok();
-}
-
-template <typename T>
-class IQTrimmer {
-    static constexpr uint8_t max_amp = 0xFF;
-    static constexpr typename T::value_type max_value = std::numeric_limits<typename T::value_type>::max();
-    static constexpr uint32_t max_mag_squared{2 * (max_value * max_value)};  // NB: Braces to detect narrowing.
-
-   public:
-    static Optional<TrimRange> ComputeTrimRange(
-        const std::filesystem::path& path,
-        uint8_t amp_threshold,  // 0 - 255
-        PowerBuckets* buckets,
-        std::function<void(uint8_t)> on_progress) {
-        TrimRange range{};
-
-        File f;
-        auto error = f.open(path);
-        if (error)
-            return {};
-
-        constexpr size_t buffer_size = std::filesystem::max_file_block_size;
-        uint8_t buffer[buffer_size];
-
-        bool has_start = false;
-        size_t sample_index = 0;
-        File::Offset offset = 0;
-        uint8_t last_progress = 0;
-        size_t samples_per_bucket = 1;
-        // Scale from 0-255 to 0-max_mag_squared.
-        uint32_t threshold = (max_mag_squared * amp_threshold) / max_amp;
-        T value{};
-
-        range.file_size = f.size();
-        range.sample_size = sizeof(T);
-        range.sample_count = range.file_size / range.sample_size;
-
-        if (buckets)
-            samples_per_bucket = std::max(1ULL, range.sample_count / buckets->size);
-
-        while (true) {
-            auto result = f.read(buffer, buffer_size);
-
-            if (!result)
-                return {};
-
-            for (size_t i = 0; i < *result; i += sizeof(T)) {
-                ++sample_index;
-
-                value = *reinterpret_cast<T*>(&buffer[i]);
-                auto real = value.real();
-                auto imag = value.imag();
-                uint32_t mag_squared = (real * real) + (imag * imag);
-
-                // Update range if above threshold.
-                if (mag_squared >= threshold) {
-                    if (has_start) {
-                        range.end = offset + i;
-                    } else {
-                        range.start = offset + i;
-                        range.end = range.start;
-                        has_start = true;
-                    }
-
-                    // Update the optional power bucket.
-                    if (buckets) {
-                        auto bucket_index = sample_index / samples_per_bucket;
-                        buckets->add(bucket_index);
-                    }
-                }
-            }
-
-            if (*result < buffer_size)
-                break;
-
-            offset += *result;
-
-            if (on_progress) {
-                uint8_t current_progress = 100 * offset / range.file_size;
-                if (last_progress != current_progress) {
-                    on_progress(current_progress);
-                    last_progress = current_progress;
-                }
-            }
-        }
-
-        return range;
-    }
+/* Data needed to trim a capture by sample range.
+ * end_sample is the sample *after* the last to keep. */
+struct TrimRange {
+    uint64_t start_sample;
+    uint64_t end_sample;
+    uint8_t sample_size;
 };
 
-inline Optional<TrimRange> ComputeTrimRange(
+/* Collects capture file metadata and samples power buckets. */
+Optional<CaptureInfo> profile_capture(
     const std::filesystem::path& path,
-    uint8_t amp_threshold = 5,
-    PowerBuckets* buckets = nullptr,
-    std::function<void(uint8_t)> on_progress = nullptr) {
-    Optional<TrimRange> range;
-    auto sample_size = std::filesystem::capture_file_sample_size(path);
+    PowerBuckets& buckets,
+    uint8_t samples_per_bucket = 10);
 
-    switch (sample_size) {
-        case sizeof(complex16_t):
-            return IQTrimmer<complex16_t>::ComputeTrimRange(path, amp_threshold, buckets, on_progress);
+/* Computes the trimming range given profiling info.
+ * Cutoff percent is a number 1-100. */
+TrimRange compute_trim_range(
+    CaptureInfo info,
+    const PowerBuckets& buckets,
+    uint8_t cutoff_percent);
 
-        case sizeof(complex8_t):
-            return IQTrimmer<complex8_t>::ComputeTrimRange(path, amp_threshold, buckets, on_progress);
+/* Trims the capture file with the specified range. */
+bool trim_capture_with_range(
+    const std::filesystem::path& path,
+    TrimRange range,
+    const std::function<void(uint8_t)>& on_progress);
 
-        default:
-            return {};
-    };
-}
+}  // namespace iq
 
-#endif /*__IQ_TRIM_H__*/
\ No newline at end of file
+#endif /*__IQ_TRIM_H__*/
diff --git a/firmware/application/ui_record_view.cpp b/firmware/application/ui_record_view.cpp
index 2ad9f71a..31e136f7 100644
--- a/firmware/application/ui_record_view.cpp
+++ b/firmware/application/ui_record_view.cpp
@@ -36,6 +36,7 @@ using namespace portapack;
 #include "utility.hpp"
 
 #include <cstdint>
+#include <vector>
 
 namespace ui {
 
@@ -303,17 +304,25 @@ void RecordView::update_status_display() {
 }
 
 void RecordView::trim_capture() {
-    if (file_type != FileType::WAV && auto_trim && !trim_path.empty()) {
-        trim_ui.show_reading();
-        auto range = ComputeTrimRange(
-            trim_path,
-            /*threshold*/ 5,
-            /*power array*/ nullptr,
-            trim_ui.get_callback());
+    using bucket_t = iq::PowerBuckets::Bucket;
+
+    if (file_type != FileType::WAV && auto_trim && !trim_path.empty()) {
+        // Need to heap alloc the buckets in this case. The large static buffer overflows the stack.
+        std::vector<bucket_t> buckets(size_t(255), bucket_t{});
+        ;
+        iq::PowerBuckets power_buckets{
+            .p = &buckets[0],
+            .size = buckets.size()};
+
+        trim_ui.show_reading();
+        auto info = iq::profile_capture(trim_path, power_buckets);
+
+        if (info) {
+            // 7% - decent trimming without being too aggressive.
+            auto trim_range = iq::compute_trim_range(*info, power_buckets, 7);
 
-        if (range) {
             trim_ui.show_trimming();
-            TrimFile(trim_path, *range);
+            iq::trim_capture_with_range(trim_path, trim_range, trim_ui.get_callback());
         }
 
         trim_ui.clear();
diff --git a/firmware/common/ui_widget.cpp b/firmware/common/ui_widget.cpp
index d6c4722e..2ed9348f 100644
--- a/firmware/common/ui_widget.cpp
+++ b/firmware/common/ui_widget.cpp
@@ -1987,6 +1987,9 @@ void SymField::set_value(uint64_t value) {
         value_[i] = uint_to_char(temp, radix);
         v /= radix;
     }
+
+    if (on_change)
+        on_change(*this);
 }
 
 void SymField::set_value(std::string_view value) {