My problem is the throughput of FFmpeg is severely limited by the speed of SMB performance. Using Wireshark I found out that FFmpeg writes are sent to my Synology SMB share in 500 byte packets with Windows 7. Running the same version of FFmpeg on Linux, on the same pc, transcoding the same file, writing to the same Synology SMB share, 65536 byte packets are sent to the SMB server resulting in almost double the throughput. How can I make Windows use larger packet sizes?
The problem is that this throughput bottleneck means using Windows for FFmpeg makes it 50% slower than running it on Linux and getting Linux servers to run it is not an option.
The same speed is achieved when writing to a Windows server SMB share, so it is not specific to the Linux Samba software.