add support for "peaks" datastream for drawing waveforms

.gitignore

@@ -0,0 +1,2 @@
+
+.DS_Store

includes/admin.form.inc

@@ -128,6 +128,13 @@ function islandora_video_admin(array $form, array &$form_state) {
       ),
     ),
   );
+  // PEAKS derivatives.
+  $form['derivatives']['islandora_video_make_peaks_locally'] = array(
+    '#type' => 'checkbox',
+    '#title' => t('Create Peaks datastream locally'),
+    '#description' => t('Generate a peaks file for audio waveform display (not yet implemented).'),
+    '#default_value' => variable_get('islandora_video_make_archive', FALSE),
+  );
 
   return system_settings_form($form);
 }

includes/derivatives.inc

@@ -144,6 +144,27 @@ function islandora_video_create_mkv(AbstractObject $object, $force = FALSE) {
   }
 }
 
+/**
+ * Creates the PEAKS derivative from the given video file.
+ *
+ * @param AbstractObject $object
+ *   An AbstractObject representing an object in Fedora.
+ * @param bool $force
+ *   Whether the derivative generation is being forced.
+ *
+ * @return array
+ *   An array describing the outcome of the PEAKS creation.
+ *
+ * @see hook_islandora_derivative()
+ */
+function islandora_video_create_peaks(AbstractObject $object, $force = FALSE) {
+  // placeholder function, not yet implemented. Needs to generate peaks file in json format using
+  // "audiowaveform": https://github.com/bbc/audiowaveform
+  // see https://wavesurfer-js.org/faq/
+  // probably needs to be a 2-step process, first extracting the audio and then generating the peaks
+  return;
+}
+
 /**
  * Create the thumbnail for the given file.
  *

islandora_video.module

@@ -182,6 +182,17 @@ function islandora_video_islandora_sp_videocmodel_islandora_derivative() {
       'file' => drupal_get_path('module', 'islandora_video') . '/includes/derivatives.inc',
     );
   }
+  if (variable_get('islandora_video_make_peaks_locally', TRUE)) {
+    $derivatives[] = array(
+      'source_dsid' => NULL,
+      'destination_dsid' => 'PEAKS',
+      'weight' => 1,
+      'function' => array(
+        'islandora_video_create_peaks',
+      ),
+      'file' => drupal_get_path('module', 'islandora_video') . '/includes/derivatives.inc',
+    );
+  }
   return $derivatives;
 }
 

theme/theme.inc

@@ -52,6 +52,13 @@ function template_preprocess_islandora_video(array &$variables) {
 
   $mime = 'video/mp4';
 
+  if (isset($object['PEAKS'])) {
+    $peaks_url = url("islandora/object/{$object->id}/datastream/PEAKS", array('absolute' => TRUE));
+	}
+  else {
+	  $peaks_url = null;
+  }
+
   $video_params = array(
     'pid' => $object->id,
   );
@@ -61,6 +68,7 @@ function template_preprocess_islandora_video(array &$variables) {
     $video_params += array(
       'mime' => $mime,
       'url' => $video_url,
+      'peaks' => $peaks_url,
     );
   }
   // Thumbnail.

xml/islandora_video_ds_composite_model.xml

@@ -24,21 +24,24 @@
   <dsTypeModel ID="TECHMD">
     <form MIME="application/xml"/>
   </dsTypeModel>
-  <dsTypeModel ID="TN" optional="false">
+  <dsTypeModel ID="TN" optional="true">
     <form MIME="image/jpeg"/>
     <form MIME="image/png"/>
     <form MIME="image/gif"/>
   </dsTypeModel>
-  <dsTypeModel ID="OGG" optional="false">
+  <dsTypeModel ID="OGG" optional="true">
     <form MIME="video/ogg"/>
   </dsTypeModel>
-  <dsTypeModel ID="MKV" optional="false">
+  <dsTypeModel ID="MKV" optional="true">
     <form MIME="video/x-matroska"/>
   </dsTypeModel>
-  <dsTypeModel ID="TECHMD_FITS" optional="false">
+  <dsTypeModel ID="TECHMD_FITS" optional="true">
     <form MIME="application/xml"/>
   </dsTypeModel>
-  <dsTypeModel ID="MP4" optional="false">
+  <dsTypeModel ID="MP4" optional="true">
     <form MIME="video/mp4"/>
   </dsTypeModel>
+  <dsTypeModel ID="PEAKS" optional="true">
+    <form MIME="application/json"/>
+  </dsTypeModel>
 </dsCompositeModel>