diff --git a/over-video.py b/over-video.py
index 76f9b22..0278440 100755
--- a/over-video.py
+++ b/over-video.py
@@ -23,7 +23,7 @@ X264_BANNED_PIXFMTS = {'bgr24'}
 # see doc/command_assembler.png
 command = over.core.types.ndict()
 command.identify = Command('ffprobe', '-v', 'quiet', '-print_format', 'json', '-show_format', '-show_streams', 'INFILE')
-command.normalize_prepass = Command('ffmpeg', '-i', 'INFILE', '-af', 'volumedetect', '-f', 'null', '/dev/null')
+command.normalize_prepass = Command('ffmpeg', '-i', 'INFILE', '-filter:a', 'volumedetect', '-f', 'null', '/dev/null')
 command.encode_generic = Command('ffmpeg', '-i', 'INFILE', 'VIDEO', 'AUDIO', '-sn', 'OUTFILE')
 command.sub_vorbis = Command('-codec:a', 'libvorbis', '-qscale:a', 'QUALITY', 'NORMALIZE')
 command.sub_pcm = Command('-codec:a', 'pcm_s16le', 'NORMALIZE')
@@ -250,18 +250,24 @@ if __name__ == '__main__':
 					elif out is None:
 						break
 				
+				pb.end()
+				
 				output = b''.join(output_buffer)
 				
 				if b'mean_volume: ' in output:
-					info.mean_volume = float(re.findall(b'mean_volume: (-\d+\.\d+) dB', output)[0])
+					info.mean_volume = float(re.findall(b'mean_volume: (-?\d+\.\d+) dB', output)[0])
+					info.max_correction = -float(re.findall(b'max_volume: (-?\d+\.\d+) dB', output)[0])
 					info.volume_correction = main.cfg.normalize_target - info.mean_volume
 				else:
 					main.print('§runexpected ffmpeg output§/, dump follows', prefix.fail, suffix=':\n')
 					print(output.decode('utf-8'))
 					raise RuntimeError
 				
-				pb.end()
-				main.print('detected volume %.1f dB, correction %.1f dB' %(info.mean_volume, info.volume_correction))
+				main.print('detected volume %.1f dB, correction %.1f dB, max. correction %.1f dB' %(info.mean_volume, info.volume_correction, info.max_correction))
+				
+				if info.volume_correction > info.max_correction:
+					d = info.volume_correction - info.max_correction
+					main.print("suggested correction is %.1f dB above the stream's maximum and will cause clipping" %(d), prefix.warn)
 			
 			else:
 				info.volume_correction = main.cfg.normalize_override
@@ -386,7 +392,11 @@ if __name__ == '__main__':
 				elif out is None:
 					break
 				
-				pb.set("s", files.tmpfile.stat().st_size)
+				try:
+					pb.set("s", files.tmpfile.stat().st_size)
+				except FileNotFoundError: # a race condition with ffmpeg
+					pass
+				
 				pb.render()
 			
 			new_filesize = over.core.text.Unit(files.tmpfile.stat().st_size, 'o')