C8 capture support (#1286)

* C8 conversion

* C8 conversion

* C8 support

* C8 support

* C8 support

* C8 support

* Don't auto-convert GPS C8 files

* C8 support

* C8 support

* C8 support

* Remove hang workaround (different PR)

* Comment change

* Clang

* Clang

* Clang

* Merged change from PR #1287

* C8 support

* C8 support

* Improve bandwidth display

* Merged minor optimization from PR 1289

* Merge change from PR 1289

* Use complex types for C8/C16 conversion

* C8 support

* C8 support

* C8 support

* C8 support

* Roll back changes

* Roll back C8 changes

* C8 support

* C8 support

* C8 support

* C8 support

* C8 support

* Don't transmit samples past EOF

* Don't transmit samples past EOF

* Clang

* Clang attempt

* Clang attempt

* C8 support

* Clang

firmware/application/CMakeLists.txt

@@ -179,6 +179,7 @@ set(CPPSRC
 	file.cpp
 	freqman_db.cpp
 	freqman.cpp
+	io_convert.cpp
 	io_file.cpp
 	io_wave.cpp
 	irq_controls.cpp

firmware/application/apps/capture_app.cpp

@@ -44,6 +44,7 @@ CaptureAppView::CaptureAppView(NavigationView& nav)
         &field_lna,
         &field_vga,
         &option_bandwidth,
+        &option_format,
         &record_view,
         &waterfall,
     });
@@ -62,6 +63,11 @@ CaptureAppView::CaptureAppView(NavigationView& nav)
         this->field_frequency.set_step(v);
     };
 
+    option_format.set_selected_index(0);  // Default to C16
+    option_format.on_change = [this](size_t, uint32_t file_type) {
+        record_view.set_file_type((RecordView::FileType)file_type);
+    };
+
     option_bandwidth.on_change = [this](size_t, uint32_t base_rate) {
         sampling_rate = 8 * base_rate;  // Decimation by 8 done on baseband side
                                         /* base_rate is used for FFT calculation and display LCD, and also in recording writing SD Card rate. */

firmware/application/apps/capture_app.hpp

@@ -58,6 +58,7 @@ class CaptureAppView : public View {
 
     Labels labels{
         {{0 * 8, 1 * 16}, "Rate:", Color::light_grey()},
+        {{11 * 8, 1 * 16}, "Format:", Color::light_grey()},
     };
 
     RSSI rssi{
@@ -87,6 +88,12 @@ class CaptureAppView : public View {
         5,
         {}};
 
+    OptionsField option_format{
+        {18 * 8, 1 * 16},
+        3,
+        {{"C16", RecordView::FileType::RawS16},
+         {"C8", RecordView::FileType::RawS8}}};
+
     RecordView record_view{
         {0 * 8, 2 * 16, 30 * 8, 1 * 16},
         u"BBD_????.*",

firmware/application/apps/replay_app.cpp

@@ -26,6 +26,8 @@
 
 #include "ui_fileman.hpp"
 #include "io_file.hpp"
+#include "io_convert.hpp"
+
 #include "baseband_api.hpp"
 #include "metadata_file.hpp"
 #include "portapack.hpp"
@@ -75,7 +77,8 @@ void ReplayAppView::on_file_changed(const fs::path& new_file_path) {
     progressbar.set_max(file_size);
     text_filename.set(truncate(file_path.filename().string(), 12));
 
-    auto duration = ms_duration(file_size, sample_rate, 4);
+    uint8_t sample_size = capture_file_sample_size(current()->path);
+    auto duration = ms_duration(file_size, sample_rate, sample_size);
     text_duration.set(to_string_time_ms(duration));
 
     button_play.focus();
@@ -110,7 +113,7 @@ void ReplayAppView::start() {
 
     std::unique_ptr<stream::Reader> reader;
 
-    auto p = std::make_unique<FileReader>();
+    auto p = std::make_unique<FileConvertReader>();
     auto open_error = p->open(file_path);
     if (open_error.is_valid()) {
         file_error();
@@ -191,7 +194,7 @@ ReplayAppView::ReplayAppView(
     };
 
     button_open.on_select = [this, &nav](Button&) {
-        auto open_view = nav.push<FileLoadView>(".C16");
+        auto open_view = nav.push<FileLoadView>(".C*");
         open_view->on_changed = [this](fs::path new_file_path) {
             on_file_changed(new_file_path);
         };

firmware/application/apps/ui_fileman.cpp

@@ -39,7 +39,10 @@ namespace fs = std::filesystem;
 namespace ui {
 static const fs::path txt_ext{u".TXT"};
 static const fs::path ppl_ext{u".PPL"};
+static const fs::path c8_ext{u".C8"};
 static const fs::path c16_ext{u".C16"};
+static const fs::path c32_ext{u".C32"};
+static const fs::path cxx_ext{u".C*"};
 static const fs::path png_ext{u".PNG"};
 static const fs::path bmp_ext{u".BMP"};
 }  // namespace ui
@@ -78,14 +81,17 @@ fs::path get_partner_file(fs::path path) {
         return {};
     auto ext = path.extension();
 
-    if (path_iequal(ext, txt_ext))
+    if (is_cxx_capture_file(path))
-        ext = c16_ext;
+        path.replace_extension(txt_ext);
-    else if (path_iequal(ext, c16_ext))
+    else if (path_iequal(ext, txt_ext)) {
-        ext = txt_ext;
+        path.replace_extension(c8_ext);
-    else
+        if (!fs::file_exists(path))
+            path.replace_extension(c16_ext);
+        if (!fs::file_exists(path))
+            path.replace_extension(c32_ext);
+    } else
         return {};
 
-    path.replace_extension(ext);
     return fs::file_exists(path) && !fs::is_directory(path) ? path : fs::path{};
 }
 
@@ -141,6 +147,7 @@ void FileManBaseView::load_directory_contents(const fs::path& dir_path) {
     current_path = dir_path;
     entry_list.clear();
     auto filtering = !extension_filter.empty();
+    bool cxx_file = path_iequal(cxx_ext, extension_filter);
 
     text_current.set(dir_path.empty() ? "(sd root)" : truncate(dir_path, 24));
 
@@ -150,7 +157,7 @@ void FileManBaseView::load_directory_contents(const fs::path& dir_path) {
             continue;
 
         if (fs::is_regular_file(entry.status())) {
-            if (!filtering || path_iequal(entry.path().extension(), extension_filter))
+            if (!filtering || path_iequal(entry.path().extension(), extension_filter) || (cxx_file && is_cxx_capture_file(entry.path())))
                 insert_sorted(entry_list, {entry.path(), (uint32_t)entry.size(), false});
         } else if (fs::is_directory(entry.status())) {
             insert_sorted(entry_list, {entry.path(), 0, true});
@@ -497,7 +504,7 @@ bool FileManagerView::handle_file_open() {
     if (path_iequal(txt_ext, ext)) {
         nav_.push<TextEditorView>(path);
         return true;
-    } else if (path_iequal(c16_ext, ext) || path_iequal(ppl_ext, ext)) {
+    } else if (is_cxx_capture_file(path) || path_iequal(ppl_ext, ext)) {
         // TODO: Enough memory to push?
         nav_.push<PlaylistView>(path);
         return true;

firmware/application/apps/ui_playlist.cpp

@@ -27,6 +27,8 @@
 #include "convert.hpp"
 #include "file_reader.hpp"
 #include "io_file.hpp"
+#include "io_convert.hpp"
+
 #include "string_format.hpp"
 #include "ui_fileman.hpp"
 #include "utility.hpp"
@@ -48,7 +50,6 @@ namespace fs = std::filesystem;
 namespace ui {
 
 // TODO: consolidate extesions into a shared header?
-static const fs::path c16_ext = u".C16";
 static const fs::path ppl_ext = u".PPL";
 
 void PlaylistView::load_file(const fs::path& playlist_path) {
@@ -258,7 +259,7 @@ void PlaylistView::send_current_track() {
         chThdSleepMilliseconds(current()->ms_delay);
 
     // Open the sample file to send.
-    auto reader = std::make_unique<FileReader>();
+    auto reader = std::make_unique<FileConvertReader>();
     auto error = reader->open(current()->path);
     if (error) {
         show_file_error(current()->path, "Can't open file to send.");
@@ -323,9 +324,10 @@ void PlaylistView::update_ui() {
         chDbgAssert(!at_end(), "update_ui #1", "current_index_ invalid");
 
         text_filename.set(current()->path.filename().string());
-        text_sample_rate.set(unit_auto_scale(current()->metadata.sample_rate, 3, 0) + "Hz");
+        text_sample_rate.set(unit_auto_scale(current()->metadata.sample_rate, 3, (current()->metadata.sample_rate > 1000000) ? 2 : 0) + "Hz");
 
-        auto duration = ms_duration(current()->file_size, current()->metadata.sample_rate, 4);
+        uint8_t sample_size = capture_file_sample_size(current()->path);
+        auto duration = ms_duration(current()->file_size, current()->metadata.sample_rate, sample_size);
         text_duration.set(to_string_time_ms(duration));
         field_frequency.set_value(current()->metadata.center_frequency);
 
@@ -336,7 +338,7 @@ void PlaylistView::update_ui() {
 
         progressbar_track.set_max(playlist_db_.size() - 1);
         progressbar_track.set_value(current_index_);
-        progressbar_transmit.set_max(current()->file_size);
+        progressbar_transmit.set_max(current()->file_size * sizeof(complex16_t) / sample_size);
     }
 
     button_play.set_bitmap(is_active() ? &bitmap_stop : &bitmap_play);
@@ -406,7 +408,7 @@ PlaylistView::PlaylistView(
     button_add.on_select = [this, &nav]() {
         if (is_active())
             return;
-        auto open_view = nav_.push<FileLoadView>(".C16");
+        auto open_view = nav_.push<FileLoadView>(".C*");
         open_view->push_dir(u"CAPTURES");
         open_view->on_changed = [this](fs::path path) {
             add_entry(std::move(path));
@@ -459,7 +461,7 @@ PlaylistView::PlaylistView(
     auto ext = path.extension();
     if (path_iequal(ext, ppl_ext))
         on_file_changed(path);
-    else if (path_iequal(ext, c16_ext))
+    else if (is_cxx_capture_file(path))
         add_entry(fs::path{path});
 }
 

firmware/application/file.cpp

@@ -21,12 +21,18 @@
  */
 
 #include "file.hpp"
+#include "complex.hpp"
 
 #include <algorithm>
 #include <codecvt>
 #include <cstring>
 #include <locale>
 
+namespace fs = std::filesystem;
+static const fs::path c8_ext{u".C8"};
+static const fs::path c16_ext{u".C16"};
+static const fs::path c32_ext{u".C32"};
+
 Optional<File::Error> File::open_fatfs(const std::filesystem::path& filename, BYTE mode) {
     auto result = f_open(&f, reinterpret_cast<const TCHAR*>(filename.c_str()), mode);
     if (result == FR_OK) {
@@ -507,6 +513,21 @@ bool path_iequal(
     return false;
 }
 
+bool is_cxx_capture_file(const path& filename) {
+    auto ext = filename.extension();
+    return path_iequal(c8_ext, ext) || path_iequal(c16_ext, ext) || path_iequal(c32_ext, ext);
+}
+
+uint8_t capture_file_sample_size(const path& filename) {
+    if (path_iequal(filename.extension(), c8_ext))
+        return sizeof(complex8_t);
+    if (path_iequal(filename.extension(), c16_ext))
+        return sizeof(complex16_t);
+    if (path_iequal(filename.extension(), c32_ext))
+        return sizeof(complex32_t);
+    return 0;
+}
+
 directory_iterator::directory_iterator(
     const std::filesystem::path& path,
     const std::filesystem::path& wild)

firmware/application/file.hpp

@@ -168,6 +168,8 @@ path operator/(const path& lhs, const path& rhs);
 
 /* Case insensitive path equality on underlying "native" string. */
 bool path_iequal(const path& lhs, const path& rhs);
+bool is_cxx_capture_file(const path& filename);
+uint8_t capture_file_sample_size(const path& filename);
 
 using file_status = BYTE;
 

firmware/application/io_convert.cpp

@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2023 Mark Thompson
+ *
+ * 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 "io_convert.hpp"
+#include "complex.hpp"
+
+namespace fs = std::filesystem;
+static const fs::path c8_ext = u".C8";
+static const fs::path c32_ext = u".C32";
+
+namespace file_convert {
+
+// Convert buffer contents from c16 to c8.
+// Same buffer used for input & output; input size is bytes; output size is bytes/2.
+void c16_to_c8(const void* buffer, File::Size bytes) {
+    complex16_t* src = (complex16_t*)buffer;
+    complex8_t* dest = (complex8_t*)buffer;
+
+    for (File::Size i = 0; i < bytes / sizeof(complex16_t); i++) {
+        auto re_out = src[i].real() >> 8;
+        auto im_out = src[i].imag() >> 8;
+        dest[i] = {(int8_t)re_out, (int8_t)im_out};
+    }
+}
+
+// Convert c8 buffer to c16 buffer.
+// Same buffer used for input & output; input size is bytes; output size is 2*bytes.
+void c8_to_c16(const void* buffer, File::Size bytes) {
+    complex8_t* src = (complex8_t*)buffer;
+    complex16_t* dest = (complex16_t*)buffer;
+    uint32_t i = bytes / sizeof(complex8_t);
+
+    if (i != 0) {
+        do {
+            i--;
+            auto re_out = (int16_t)src[i].real() * 256;  // C8 to C16 conversion;
+            auto im_out = (int16_t)src[i].imag() * 256;  // Can't shift signed numbers left, so using multiply
+            dest[i] = {(int16_t)re_out, (int16_t)im_out};
+        } while (i != 0);
+    }
+}
+
+// Convert c32 buffer to c16 buffer.
+// Same buffer used for input & output; input size is bytes; output size is bytes/2.
+void c32_to_c16(const void* buffer, File::Size bytes) {
+    complex32_t* src = (complex32_t*)buffer;
+    complex16_t* dest = (complex16_t*)buffer;
+
+    for (File::Size i = 0; i < bytes / sizeof(complex32_t); i++) {
+        auto re_out = src[i].real() >> 16;
+        auto im_out = src[i].imag() >> 16;
+        dest[i] = {(int8_t)re_out, (int8_t)im_out};
+    }
+}
+
+} /* namespace file_convert */
+
+// Automatically enables C8/C16 or C32/C16 conversion based on file extension
+Optional<File::Error> FileConvertReader::open(const std::filesystem::path& filename) {
+    convert_c8_to_c16 = path_iequal(filename.extension(), c8_ext);
+    convert_c32_to_c16 = path_iequal(filename.extension(), c32_ext);
+    return file_.open(filename);
+}
+
+// If C8 conversion enabled, half the number of bytes are read from the file & expanded to fill the whole buffer.
+// If C32 conversion enabled, the full byte count is read from the file, and compressed to half the buffer size.
+File::Result<File::Size> FileConvertReader::read(void* const buffer, const File::Size bytes) {
+    auto read_result = file_.read(buffer, convert_c8_to_c16 ? bytes / 2 : bytes);
+    if (read_result.is_ok()) {
+        if (convert_c8_to_c16) {
+            file_convert::c8_to_c16(buffer, read_result.value());
+            read_result = read_result.value() * 2;
+        } else if (convert_c32_to_c16) {
+            file_convert::c32_to_c16(buffer, read_result.value());
+            read_result = read_result.value() / 2;
+        }
+        bytes_read_ += read_result.value();
+    }
+    return read_result;
+}
+
+// Automatically enables C8/C16 conversion based on file extension
+Optional<File::Error> FileConvertWriter::create(const std::filesystem::path& filename) {
+    convert_c16_to_c8 = path_iequal(filename.extension(), c8_ext);
+    return file_.create(filename);
+}
+
+// If C8 conversion is enabled, half the number of bytes are written to the file.
+File::Result<File::Size> FileConvertWriter::write(const void* const buffer, const File::Size bytes) {
+    if (convert_c16_to_c8) {
+        file_convert::c16_to_c8(buffer, bytes);
+    }
+    auto write_result = file_.write(buffer, convert_c16_to_c8 ? bytes / 2 : bytes);
+    if (write_result.is_ok()) {
+        if (convert_c16_to_c8) {
+            write_result = write_result.value() * 2;
+        }
+        bytes_written_ += write_result.value();
+    }
+    return write_result;
+}

firmware/application/io_convert.hpp

@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2023 Mark Thompson
+ *
+ * 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.
+ */
+
+#pragma once
+
+#include "io_file.hpp"
+
+#include "io.hpp"
+#include "file.hpp"
+#include "optional.hpp"
+
+#include <cstdint>
+
+namespace file_convert {
+
+void c8_to_c16(const void* buffer, File::Size bytes);
+void c32_to_c16(const void* buffer, File::Size bytes);
+void c16_to_c8(const void* buffer, File::Size bytes);
+
+} /* namespace file_convert */
+
+class FileConvertReader : public stream::Reader {
+   public:
+    FileConvertReader() = default;
+
+    FileConvertReader(const FileConvertReader&) = delete;
+    FileConvertReader& operator=(const FileConvertReader&) = delete;
+    FileConvertReader(FileConvertReader&& file) = delete;
+    FileConvertReader& operator=(FileConvertReader&&) = delete;
+
+    Optional<File::Error> open(const std::filesystem::path& filename);
+
+    File::Result<File::Size> read(void* const buffer, const File::Size bytes) override;
+    const File& file() const& { return file_; }
+
+    bool convert_c8_to_c16{};
+    bool convert_c32_to_c16{};
+
+   protected:
+    File file_{};
+    uint64_t bytes_read_{0};
+};
+
+class FileConvertWriter : public stream::Writer {
+   public:
+    FileConvertWriter() = default;
+
+    FileConvertWriter(const FileConvertWriter&) = delete;
+    FileConvertWriter& operator=(const FileConvertWriter&) = delete;
+    FileConvertWriter(FileConvertWriter&& file) = delete;
+    FileConvertWriter& operator=(FileConvertWriter&&) = delete;
+
+    Optional<File::Error> create(const std::filesystem::path& filename);
+
+    File::Result<File::Size> write(const void* const buffer, const File::Size bytes) override;
+    const File& file() const& { return file_; }
+
+    bool convert_c16_to_c8{};
+
+   protected:
+    File file_{};
+    uint64_t bytes_written_{0};
+};

firmware/application/ui_record_view.cpp

@@ -26,6 +26,7 @@ using namespace portapack;
 
 #include "io_file.hpp"
 #include "io_wave.hpp"
+#include "io_convert.hpp"
 
 #include "baseband_api.hpp"
 #include "metadata_file.hpp"
@@ -194,6 +195,7 @@ void RecordView::start() {
             }
         } break;
 
+        case FileType::RawS8:
         case FileType::RawS16: {
             const auto metadata_file_error =
                 write_metadata_file(get_metadata_path(base_path),
@@ -204,8 +206,8 @@ void RecordView::start() {
                 return;
             }
 
-            auto p = std::make_unique<RawFileWriter>();
+            auto p = std::make_unique<FileConvertWriter>();
-            auto create_error = p->create(base_path.replace_extension(u".C16"));
+            auto create_error = p->create(base_path.replace_extension((file_type == FileType::RawS8) ? u".C8" : u".C16"));
             if (create_error.is_valid()) {
                 handle_error(create_error.value());
             } else {

firmware/application/ui_record_view.hpp

@@ -40,8 +40,10 @@ class RecordView : public View {
     std::function<void(std::string)> on_error{};
 
     enum FileType {
+        RawS8 = 1,
         RawS16 = 2,
-        WAV = 3,
+        RawS32 = 3,
+        WAV = 4,
     };
 
     RecordView(
@@ -57,6 +59,8 @@ class RecordView : public View {
 
     void set_sampling_rate(const size_t new_sampling_rate);
 
+    void set_file_type(const FileType v) { file_type = v; }
+
     void start();
     void stop();
     void on_hide() override;
@@ -83,7 +87,7 @@ class RecordView : public View {
 
     const std::filesystem::path filename_stem_pattern;
     const std::filesystem::path folder;
-    const FileType file_type;
+    FileType file_type;
     const size_t write_size;
     const size_t buffer_count;
     size_t sampling_rate{0};

firmware/baseband/proc_gps_sim.cpp

@@ -44,27 +44,27 @@ ReplayProcessor::ReplayProcessor() {
 void ReplayProcessor::execute(const buffer_c8_t& buffer) {
     /* 2.6MHz, 2048 samples */
 
-    if (!configured) return;
+    if (!configured || !stream) return;
 
     // File data is in C8 format, which is what we need
     // File samplerate is 2.6MHz, which is what we need
     // To fill up the 2048-sample C8 buffer @ 2 bytes per sample = 4096 bytes
-    if (stream) {
+    const size_t bytes_to_read = sizeof(*buffer.p) * 1 * (buffer.count);
-        const size_t bytes_to_read = sizeof(*buffer.p) * 1 * (buffer.count);
+    size_t bytes_read_this_iteration = stream->read(iq_buffer.p, bytes_to_read);
-        size_t bytes_read_this_iteration = stream->read(iq_buffer.p, bytes_to_read);
+    size_t samples_read_this_iteration = bytes_read_this_iteration / sizeof(*buffer.p);
-        bytes_read += bytes_read_this_iteration;
 
-        // NB: Couldn't we have just read the data into buffer.p to start with, or some DMA/cache coherency concern?
+    bytes_read += bytes_read_this_iteration;
-        //
-        // for (size_t i = 0; i < buffer.count; i++) {
-        //     auto re_out = iq_buffer.p[i].real();
-        //     auto im_out = iq_buffer.p[i].imag();
-        //     buffer.p[i] = {(int8_t)re_out, (int8_t)im_out};
-        // }
-        memcpy(buffer.p, iq_buffer.p, bytes_read_this_iteration);  // memcpy should be more efficient than 1 byte at a time
-    }
 
-    spectrum_samples += buffer.count;
+    // NB: Couldn't we have just read the data into buffer.p to start with, or some DMA/cache coherency concern?
+    //
+    // for (size_t i = 0; i < buffer.count; i++) {
+    //     auto re_out = iq_buffer.p[i].real();
+    //     auto im_out = iq_buffer.p[i].imag();
+    //     buffer.p[i] = {(int8_t)re_out, (int8_t)im_out};
+    // }
+    memcpy(buffer.p, iq_buffer.p, bytes_read_this_iteration);  // memcpy should be more efficient than 1 byte at a time
+
+    spectrum_samples += samples_read_this_iteration;
     if (spectrum_samples >= spectrum_interval_samples) {
         spectrum_samples -= spectrum_interval_samples;
 

firmware/baseband/proc_replay.cpp

@@ -43,7 +43,7 @@ ReplayProcessor::ReplayProcessor() {
 void ReplayProcessor::execute(const buffer_c8_t& buffer) {
     /* 4MHz, 2048 samples */
 
-    if (!configured) return;
+    if (!configured || !stream) return;
 
     // File data is in C16 format, we need C8
     // File samplerate is 500kHz, we're at 4MHz
@@ -52,13 +52,14 @@ void ReplayProcessor::execute(const buffer_c8_t& buffer) {
     // 2048 samples * 2 bytes per sample = 4096 bytes
     // Since we're oversampling by 4M/500k = 8, we only need 2048/8 = 256 samples from the file and duplicate them 8 times each
     // So 256 * 4 bytes per sample (C16) = 1024 bytes from the file
-    if (stream) {
+    const size_t bytes_to_read = sizeof(*buffer.p) * 2 * (buffer.count / 8);  // *2 (C16), /8 (oversampling) should be == 1024
-        const size_t bytes_to_read = sizeof(*buffer.p) * 2 * (buffer.count / 8);  // *2 (C16), /8 (oversampling) should be == 1024
+    size_t bytes_read_this_iteration = stream->read(iq_buffer.p, bytes_to_read);
-        bytes_read += stream->read(iq_buffer.p, bytes_to_read);
+    size_t oversamples_this_iteration = bytes_read_this_iteration * 8 / (sizeof(*buffer.p) * 2);
-    }
+
+    bytes_read += bytes_read_this_iteration;
 
     // Fill and "stretch"
-    for (size_t i = 0; i < buffer.count; i++) {
+    for (size_t i = 0; i < oversamples_this_iteration; i++) {
         if (i & 7) {
             buffer.p[i] = buffer.p[i - 1];
         } else {
@@ -68,7 +69,7 @@ void ReplayProcessor::execute(const buffer_c8_t& buffer) {
         }
     }
 
-    spectrum_samples += buffer.count;
+    spectrum_samples += oversamples_this_iteration;
     if (spectrum_samples >= spectrum_interval_samples) {
         spectrum_samples -= spectrum_interval_samples;
         channel_spectrum.feed(iq_buffer, channel_filter_low_f, channel_filter_high_f, channel_filter_transition);