From d75e699fa67e2ca8ea670c79090493e326730a6f Mon Sep 17 00:00:00 2001
From: Cedric Spindler <cedric.spindler@gmail.com>
Date: Mon, 4 Dec 2023 13:56:21 +0100
Subject: [PATCH] Split spectrogram for long files

---
 batdetect2_gui/generate_data.py        | 25 ++++++++++++++++++++-----
 batdetect2_gui/templates/annotate.html |  8 +++++++-
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/batdetect2_gui/generate_data.py b/batdetect2_gui/generate_data.py
index 7779b1a..57052bf 100644
--- a/batdetect2_gui/generate_data.py
+++ b/batdetect2_gui/generate_data.py
@@ -65,11 +65,26 @@ def compute_image_data(audio_raw, sampling_rate, spec_params):
     cmap = plt.get_cmap("inferno")
     spec = (cmap(spec_raw)[:, :, :3] * 255).astype(np.uint8)
 
+    n_segments = 4
+    segment_width = spec.shape[1] // n_segments
+
+    # split spec into multiple parts along the x axis
+    spec_parts = []
+    for i in range(n_segments):
+        start = i * segment_width
+        # For the last segment, take all remaining columns
+        # to handle non-divisible cases
+        end = None if i == n_segments - 1 else start + segment_width
+        segment = spec[:, start:end, :]
+        spec_parts.append(segment)
+
     # create output image
-    im = Image.fromarray(spec)
-    im_file = BytesIO()
-    im.save(im_file, "JPEG", quality=90)
-    im_data = base64.b64encode(im_file.getvalue()).decode("utf-8")
-    im_file.close()
+    im_data = []
+    for i, spec_part in enumerate(spec_parts):
+        im = Image.fromarray(spec_part)
+        im_file = BytesIO()
+        im.save(im_file, "JPEG", quality=90)
+        im_data.append(base64.b64encode(im_file.getvalue()).decode("utf-8"))
+        im_file.close()
 
     return im_data, spec.shape
diff --git a/batdetect2_gui/templates/annotate.html b/batdetect2_gui/templates/annotate.html
index f7181fa..39e8f86 100755
--- a/batdetect2_gui/templates/annotate.html
+++ b/batdetect2_gui/templates/annotate.html
@@ -10,7 +10,13 @@
     <!--<img src='/static/hz_scale_150_right.png' />-->
   </div>
   <div class="spec_well">
-    <img id="spec_im" src="data:image/jpeg;base64,{{im_data}}" alt="{{annotation.id}}" />
+    <div id="spec_im" style="width: {{ file_params.spec_width }}px">
+        <div id="specgroup" style="display: grid; grid-template-columns: 1fr 1fr 1fr 1fr;width: {{ file_params.spec_width }}px">
+          {% for item in im_data %}
+          <img src="data:image/jpeg;base64,{{item}}" alt="{{annotation.id}}" />
+          {% endfor %}
+        </div>
+    </div>
 
     <div class="progress" id="progress">
       <div class="progress-bar" id="progress-bar" role="progressbar" aria-valuenow="0" aria-valuemin="0" aria-valuemax="100"></div>