- Implemented.

Safari/iPhone recording now uses MP4/AAC when WebM is unavailable.
WebM remains the default when supported and FFmpeg is disabled.
Added optional FFmpeg profiles: recommended M4A/AAC-LC or requested 
MP4/H.264 + AAC.
Added MIME-aware, playsinline audio playback.
Added dashboard controls under Plans & Platform → Voice Transcoding / 
FFmpeg.
Added Apache/Nginx media MIME configuration and documentation.
Core implementation: voice_transcoder.php (line 72), messages.php (line 
86), and cyberchat-app.js (line 635).

api/archive.php

@@ -47,6 +47,7 @@ $payload = array_map(function(array $row): array {
         'id' => (int)$row['id'],
         'message' => $row['message'], 'message_type' => $row['message_type'],
         'voice_url' => $row['message_type'] === 'voice' && !empty($row['voice_file']) ? voicePublicPath($row['voice_file']) : null,
+        'voice_mime' => $row['voice_mime'] ?? null,
         'voice_duration' => $row['voice_duration'] !== null ? (float)$row['voice_duration'] : null,
         'created_at' => (int)$row['created_at'], 'day_key' => $row['day_key'],
     ];

api/config.php

@@ -21,6 +21,8 @@ jsonResponse([
         'max_duration_seconds' => $config['voice']['max_duration_seconds'] ?? 60,
         'max_upload_bytes' => $config['voice']['max_upload_bytes'] ?? 12582912,
         'auto_play_default' => $config['voice']['auto_play_default'] ?? true,
+        'transcoding_enabled' => $config['voice']['transcoding']['enabled'] ?? false,
+        'output_profile' => $config['voice']['transcoding']['profile'] ?? 'm4a_aac',
     ],
     'subscriptions' => ['enabled' => $config['subscriptions']['enabled'] ?? true],
 ]);

api/messages.php

@@ -1,6 +1,7 @@
 <?php
 define('CYBERCHAT_API', true);
 require_once __DIR__ . '/../bootstrap.php';
+require_once ROOT_DIR . '/lib/voice_transcoder.php';
 sendCorsHeaders();
 
 try { archiveYesterdayIfNeeded(); } catch (Throwable $e) { error_log($e->getMessage()); }
@@ -83,26 +84,48 @@ function sendVoiceMessage(): never {
     }
 
     $mime = class_exists('finfo') ? (string)(new finfo(FILEINFO_MIME_TYPE))->file($file['tmp_name']) : '';
-    $header = (string)file_get_contents($file['tmp_name'], false, null, 0, 12);
+    $header = (string)file_get_contents($file['tmp_name'], false, null, 0, 16);
     if (str_starts_with($header, "\x1A\x45\xDF\xA3")) $mime = 'audio/webm';
     elseif (str_starts_with($header, 'RIFF') && substr($header, 8, 4) === 'WAVE') $mime = 'audio/wav';
+    elseif (strlen($header) >= 8 && substr($header, 4, 4) === 'ftyp') $mime = 'audio/mp4';
+    elseif (strlen($header) >= 2 && ord($header[0]) === 0xFF && (ord($header[1]) & 0xF0) === 0xF0) $mime = 'audio/aac';
     $allowed = [
         'audio/webm' => 'webm',
         'video/webm' => 'webm',
         'audio/wav' => 'wav',
         'audio/x-wav' => 'wav',
         'audio/wave' => 'wav',
+        'audio/mp4' => 'm4a',
+        'video/mp4' => 'm4a',
+        'audio/aac' => 'aac',
+        'audio/x-aac' => 'aac',
     ];
-    if (!isset($allowed[$mime])) jsonResponse(['error' => 'Voice clips must be WAV or WebM'], 400);
+    if (!isset($allowed[$mime])) jsonResponse(['error' => 'Voice clips must be WebM, MP4/M4A, AAC, or WAV'], 400);
 
     $dir = voiceUploadDir();
     ensureWritableDirectory($dir, 'Voice storage');
-    $filename = bin2hex(random_bytes(20)) . '.' . $allowed[$mime];
-    if (!move_uploaded_file($file['tmp_name'], $dir . '/' . $filename)) {
+    $token = bin2hex(random_bytes(20));
+    $sourceFilename = $token . '.' . $allowed[$mime];
+    $sourcePath = $dir . '/' . $sourceFilename;
+    if (!move_uploaded_file($file['tmp_name'], $sourcePath)) {
         jsonResponse(['error' => 'Could not store voice clip'], 500);
     }
 
-    $storedMime = $mime === 'video/webm' ? 'audio/webm' : $mime;
+    $sourceMime = match ($mime) {
+        'video/webm' => 'audio/webm',
+        'video/mp4' => 'audio/mp4',
+        'audio/x-wav', 'audio/wave' => 'audio/wav',
+        'audio/x-aac' => 'audio/aac',
+        default => $mime,
+    };
+    try {
+        $stored = transcodeVoiceRecording($sourcePath, $sourceFilename, $sourceMime);
+    } catch (Throwable $e) {
+        if (is_file($sourcePath)) @unlink($sourcePath);
+        throw $e;
+    }
+    $filename = $stored['filename'];
+    $storedMime = $stored['mime'];
     $db = getDB();
     try {
         $db->prepare("INSERT INTO messages