Improve error handling.

src/tscut/tools/ffmpeg.py

@@ -14,6 +14,7 @@ from tqdm import tqdm
 from typeguard import typechecked
 
 from tscut.exceptions import ExternalToolError, InvalidMediaError, TemporaryFileError
+from tscut.temporaries import TemporaryFiles
 from tscut.tools.ffprobe import (
     get_frames_in_stream,
     get_video_dimensions,
@@ -21,7 +22,6 @@ from tscut.tools.ffprobe import (
 )
 from tscut.tools.ppm import dump_ppm
 from tscut.tools.timeframe import get_packet_duration, parse_timestamp
-from tscut.temporaries import TemporaryFiles
 
 logger = logging.getLogger(__name__)
 
@@ -263,8 +263,6 @@ def extract_all_streams(ffmpeg_path:str, ffprobe_path:str, input_file:IO[bytes],
                 logger.debug("Found %d packets to be extracted from audio track.", nb_packets)
                 if nb_packets > 0:
                     packet_duration = get_packet_duration(packets[0])
-                    if packet_duration is None:
-                        return None
                 else:
                     packet_duration = 0