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gr-satnogs
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Code Issues Releases Wiki Activity

Final cleanup and some more comments

This commit is contained in:
Sebastian 2018-01-04 16:06:54 +01:00 committed by Sebastian
parent a844248164
commit 5e8958703f
2 changed files with 82 additions and 15 deletions
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86
lib/noaa_apt_sink_impl.cc
View File

@ -107,18 +107,27 @@ namespace gr
void
noaa_apt_sink_impl::init_images () {
// Split the filename option into path + filename and extension
size_t len = d_filename_png.size();
size_t pos = d_filename_png.rfind('.');
std::string base_filename = d_filename_png.substr(0, pos);
std::string extension = d_filename_png.substr(pos+1, len-1);
d_full_filename = base_filename + std::to_string(d_num_images) + "." + extension;
// Construct numbered filename for the full image
d_full_filename = base_filename + std::to_string(d_num_images)
+ "." + extension;
// Create a new empty png
d_full_image = png::image<png::gray_pixel>(d_width, d_height);
if(d_split) {
d_left_filename = base_filename + "_left" + std::to_string(d_num_images) + "." + extension;
d_right_filename = base_filename + "_right" + std::to_string(d_num_images)+ "." + extension;
if(d_split) {
// In case split images are requested construct filenames for those as well
d_left_filename = base_filename + "_left"
+ std::to_string(d_num_images) + "." + extension;
d_right_filename = base_filename + "_right"
+ std::to_string(d_num_images)+ "." + extension;
// Create new empty pngs for the split images
d_left_image = png::image<png::gray_pixel>(d_width/2, d_height);
d_right_image = png::image<png::gray_pixel>(d_width/2, d_height);
}
@ -126,22 +135,30 @@ namespace gr
void
noaa_apt_sink_impl::write_image (png::image<png::gray_pixel> image, std::string filename) {
noaa_apt_sink_impl::write_image (png::image<png::gray_pixel> image,
std::string filename)
{
// In case the flip option is set
if(d_flip) {
size_t width = image.get_width();
size_t height = image.get_height();
// An image of same size is created ...
png::image<png::gray_pixel> flipped(width, height);
// ... and all the lines are copied over reverse order
for(size_t y = 0; y < height; y++) {
for(size_t x = 0; x < width; x++) {
auto pixel = image.get_pixel(x, height - y - 1);
flipped.set_pixel(x, y, pixel);
}
}
// Write out the flipped image
flipped.write(filename);
}
// In case the flip option is not set
else {
// Write out the original
image.write(filename);
}
}
@ -149,9 +166,11 @@ namespace gr
void
noaa_apt_sink_impl::write_images () {
// Write out the full image
write_image(d_full_image, d_full_filename);
if(d_split) {
// Write out the split images if the split option is enabled
write_image(d_left_image, d_left_filename);
write_image(d_right_image, d_right_filename);
}
@ -159,15 +178,20 @@ namespace gr
noaa_apt_sink_impl::~noaa_apt_sink_impl () {
// Nothing happens here
}
bool
noaa_apt_sink_impl::stop () {
// As a teardown action, the remaining pngs
//should be cropped to the correct size and written to disk
// Grab the buffers from the fullsize pngs
auto buf_full_image = d_full_image.get_pixbuf();
auto buf_left_image = d_left_image.get_pixbuf();
auto buf_right_image = d_right_image.get_pixbuf();
// Create new smaller pngs using the old buffers
d_full_image = png::image<png::gray_pixel>(d_width, d_current_y + 1);
d_full_image.set_pixbuf(buf_full_image);
@ -177,6 +201,7 @@ namespace gr
d_right_image = png::image<png::gray_pixel>(d_width/2, d_current_y + 1);
d_right_image.set_pixbuf(buf_right_image);
// Write the smaller images to disk
write_images();
return true;
@ -184,10 +209,15 @@ namespace gr
void noaa_apt_sink_impl::set_pixel (size_t x, size_t y, float sample) {
// Adjust dynamic range, using minimum and maximum values
sample = (sample - f_min_level) / (f_max_level - f_min_level) * 255;
// Set the pixel in the full image
d_full_image.set_pixel(x, y, sample);
// Id the split otions is set
if(d_split) {
// Set the pixel in the right image,
// depending on its coordinate
if(x < d_width / 2) {
d_left_image.set_pixel(x, y, sample);
}
@ -200,24 +230,35 @@ namespace gr
void
noaa_apt_sink_impl::skip_to (size_t new_x, size_t pos, const float *samples) {
// Check if the skip is forward or backward
if(new_x > d_current_x) {
// In case it is forward there will be a new_x - d_current_x sized hole
// in the image. Holes up 39 pixels can be filled from the modules history
size_t dist = std::min(size_t(39), new_x - d_current_x);
// Fill the hole using the previous samples of pos
for(size_t i = 0; i < dist; i++) {
set_pixel(new_x - dist + i, d_current_y, samples[pos - dist + i]);
}
}
// Jump to new location
d_current_x = new_x;
}
noaa_apt_sync_marker
noaa_apt_sink_impl::is_marker(size_t pos, const float *samples) {
// Initialize counters for 'hacky' correlation
size_t count_a = 0;
size_t count_b = 0;
for(size_t i = 0; i < 40; i++) {
// history of previous 39 samples + current one
// -> start 39 samples in the past
float sample = samples[pos - 39 + i];
// Remove DC-offset (aka. the average value of the sync pattern)
sample = sample - f_average;
// Very basic 1/0 correlation between pattern constan and history
if((sample > 0 && synca_seq[i]) || (sample < 0 && !syncb_seq[i])) {
count_a += 1;
}
@ -228,6 +269,7 @@ namespace gr
}
// Prefer sync pattern a as it is detected more reliable
if(count_a > 35) {
return noaa_apt_sync_marker::SYNC_A;
}
@ -247,26 +289,43 @@ namespace gr
{
const float *in = (const float *) input_items[0];
for (size_t i = d_history_length - 1; i < noutput_items + d_history_length - 1; i++) {
// Structure of in[]:
// - d_history_length many historical samples
// - noutput_items many samples to process
for (size_t i = d_history_length - 1;
i < noutput_items + d_history_length - 1; i++) {
// Get the current sample
float sample = in[i];
// Update min and max level to adjust dynamic range in set pixel
f_max_level = std::fmax(f_max_level, sample);
f_min_level = std::fmin(f_min_level, sample);
// Update exponential smoothing average used in sync pattern detection
f_average = f_average_alpha * sample + (1.0 - f_average_alpha) * f_average;
// If line sync is enabled
if(d_synchronize_opt) {
if(is_marker(i, in) == noaa_apt_sync_marker::SYNC_A) {
// Check if the history for the current sample is a sync pattern
noaa_apt_sync_marker marker = is_marker(i, in);
// For pattern a
if(marker == noaa_apt_sync_marker::SYNC_A) {
// Skip to right location, pattern starts 40 samples in the past
skip_to(39, i, in);
// If this is the first sync, reset min and max
if(!d_has_sync) {
f_max_level = 0.0;
f_min_level = 1.0;
d_has_sync = true;
}
}
else if(is_marker(i, in) == noaa_apt_sync_marker::SYNC_B) {
// For pattern b
else if(marker == noaa_apt_sync_marker::SYNC_B) {
// Skip to right location, pattern starts 40 samples in the past
skip_to(d_width / 2 + 39, i, in);
// If this is the first sync, reset min and max
if(!d_has_sync) {
f_max_level = 0.0;
f_min_level = 1.0;
@ -275,17 +334,24 @@ namespace gr
}
}
// Set the the pixel at the current position
set_pixel(d_current_x, d_current_y, sample);
// Increment x position
d_current_x += 1;
// If we are beyond the end of line
if(d_current_x >= d_width) {
// Increment y position
d_current_y += 1;
// Reset x position to line start
d_current_x = 0;
// If there are enough lines decoded write the image to disk
if(d_current_y % d_row_write_threshold == 0) {
write_images();
}
// Split the image if there are enough lines decoded
if(d_current_y >= d_height) {
d_current_y = 0;
d_num_images += 1;
@ -295,7 +361,7 @@ namespace gr
}
}
// Tell gnu radio how many samples were consumed
return noutput_items;
}

11
lib/noaa_apt_sink_impl.h
View File

@ -76,22 +76,23 @@ namespace gr
work (int noutput_items, gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items);
// For teardown actions, like writing the remaining images to disk
bool
stop ();
private:
// Generate empty images and filenames to save them to
// Generates new empty images and the filenames for them
void
init_images ();
/*
* Check if the history portion of the input contains a sync marker.
* Checks if the history portion of the input contains a sync marker.
* Matches the 40 samples before pos against the patterns.
*/
noaa_apt_sync_marker
is_marker (size_t pos, const float *samples);
// Set the pixel indicated by coordinates in the images (both full and split)
// Sets the pixel indicated by coordinates in the images (both full and split)
void
set_pixel (size_t x, size_t y, float sample);
@ -102,11 +103,11 @@ namespace gr
void
skip_to (size_t new_x, size_t pos, const float *samples);
// Write the images to disk
// Writes all images to disk
void
write_images ();
// Write a single image to disk, also takes care of flipping
// Writes a single image to disk, also takes care of flipping
void
write_image (png::image<png::gray_pixel> image, std::string filename);
};