from asammdf import MDF mdf = MDF("my_vehicle_log.mf4") print(mdf) # Displays metadata, channel count, and duration Even with modern tools, BLF to MF4 conversion can hit snags. Here are the latest fixes for 2025. Problem 1: "Unsupported Bus Type" Error: ValueError: Unknown bus type 5 Cause: The BLF contains FlexRay or Ethernet data that asammdf cannot parse natively. Solution: Use Vector’s blf2mdf.exe or filter the BLF to only CAN channels using Vector CANalyzer’s conversion matrix. Problem 2: Timestamp Overflow (The 48-hour bug) Error: Timestamps appear as negative numbers or wrap around. Cause: Old BLF files use 32-bit microsecond timestamps that overflow. New fix: In asammdf , force 64-bit conversion:
convert_blf_to_mf4(sys.argv[1], sys.argv[2]) python convert_blf.py my_vehicle_log.blf my_vehicle_log.mf4 Step 4: Verification (Optional but Recommended) Load the new MF4 back into asammdf to verify channels: convert blf to mf4 new
mdf = MDF(input_path, sync_timestamps=True) Error: MF4 output is 10x larger than the BLF input. Cause: Default MF4 saves XML data uncompressed. Fix: Use compression=2 (Deflate) or compression=3 (LZ4) when saving: from asammdf import MDF mdf = MDF("my_vehicle_log
The "new" CLI and Python methods are roughly 4x faster than the old GUI workflow. The Future: Beyond MF4 (And Why You Still Need This) You might wonder: Is MF4 still relevant? With the rise of Apache Parquet and Arrow Flight , some teams are skipping MF4. However, ASAM MDF 4.20 (released Q4 2024) adds native support for Zstandard compression and JSON-based attachments. Solution: Use Vector’s blf2mdf