livephoto: multiple trailers in Google (fix #373)

lib/Controller/VideoController.php

@@ -139,6 +139,15 @@ class VideoController extends ApiBase
             } catch (\Exception $e) {
                 return new JSONResponse(['message' => 'Embedded video not found'], Http::STATUS_NOT_FOUND);
             }
+        } elseif (str_starts_with($liveid, 'self__traileroffset=')) {
+            // Remove prefix
+            $offset = (int) substr($liveid, \strlen('self__traileroffset='));
+            if ($offset <= 0) {
+                return new JSONResponse(['message' => 'Invalid offset'], Http::STATUS_BAD_REQUEST);
+            }
+
+            // Read file from offset to end
+            $blob = file_get_contents($path, false, null, $offset);
         } else {
             // Get stored video file (Apple MOV)
             $lp = $this->timelineQuery->getLivePhoto($fileid);

lib/Db/LivePhoto.php

@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace OCA\Memories\Db;
 
+use OCA\Memories\Exif;
 use OCP\DB\QueryBuilder\IQueryBuilder;
 use OCP\Files\File;
 use OCP\IDBConnection;
@@ -26,7 +27,7 @@ class LivePhoto
     }
 
     /** Get liveid from photo part */
-    public function getLivePhotoId(array &$exif)
+    public function getLivePhotoId(File &$file, array &$exif)
     {
         // Apple JPEG (MOV has ContentIdentifier)
         if (\array_key_exists('MediaGroupUUID', $exif)) {
@@ -41,7 +42,36 @@ class LivePhoto
         // Google JPEG and Samsung HEIC (Apple?)
         if (\array_key_exists('MotionPhoto', $exif)) {
             if ('image/jpeg' === $exif['MIMEType']) {
-                // Google JPEG -- image should hopefully be in trailer
+                // Google Motion Photo JPEG
+
+                // We need to read the DirectoryItemLength key to get the length of the video
+                // These keys are duplicate, one for the image and one for the video
+                // With exiftool -G4, we get the following:
+                //
+                //    "Unknown:DirectoryItemSemantic": "Primary"
+                //    "Unknown:DirectoryItemLength": 0
+                //    "Copy1:DirectoryItemSemantic": "MotionPhoto"
+                //    "Copy1:DirectoryItemLength": 3011435    // <-- this is the length of the video
+                //
+                // The video is then located at the end of the file, so we can get the offset.
+                // Match each DirectoryItemSemantic to find MotionPhoto, then get the length.
+                $path = $file->getStorage()->getLocalFile($file->getInternalPath());
+                $extExif = Exif::getExifWithDuplicates($path);
+
+                foreach ($extExif as $key => $value) {
+                    if (str_ends_with($key, ':DirectoryItemSemantic')) {
+                        if ('MotionPhoto' === $value) {
+                            $videoLength = $extExif[str_replace('Semantic', 'Length', $key)];
+                            if (\is_int($videoLength) && $videoLength > 0) {
+                                $videoOffset = $file->getSize() - $videoLength;
+
+                                return 'self__traileroffset='.((string) $videoOffset);
+                            }
+                        }
+                    }
+                }
+
+                // Fallback: video should hopefully be in trailer
                 return 'self__trailer';
             }
             if ('image/heic' === $exif['MIMEType']) {

lib/Exif.php

@@ -282,6 +282,11 @@ class Exif
         }
     }
 
+    public static function getExifWithDuplicates(string $path)
+    {
+        return self::getExifFromLocalPathWithSeparateProc($path, ['-G4']);
+    }
+
     /** Get path to exiftool binary */
     private static function getExiftool()
     {
@@ -407,10 +412,10 @@ class Exif
         }
     }
 
-    private static function getExifFromLocalPathWithSeparateProc(string &$path)
+    private static function getExifFromLocalPathWithSeparateProc(string &$path, array $extraArgs = [])
     {
         $pipes = [];
-        $proc = proc_open(array_merge(self::getExiftool(), ['-api', 'QuickTimeUTC=1', '-n', '-U', '-json', '--b', $path]), [
+        $proc = proc_open(array_merge(self::getExiftool(), ['-api', 'QuickTimeUTC=1', '-n', '-U', '-json', '--b'], $extraArgs, [$path]), [
             1 => ['pipe', 'w'],
             2 => ['pipe', 'w'],
         ], $pipes);