I got a little further. #updateErrorPipelineStream helped to get the error messages as they came.
p := PipeableOSProcess command: '/usr/local/bin/HandBrakeCLI -e x264 -q 20 -m --start-at duration:1 --stop-at duration:5 -i /Volumes/DISK_01 -o "/path/to/DISK_01.mp4"'. [p isComplete] whileFalse: [ p updateErrorPipelineStream. Transcript show: p errorUpToEnd ].
-- View this message in context: http://forum.world.st/PipeableOSProcess-incremental-output-tp3946435p3946565... Sent from the Squeak - Beginners mailing list archive at Nabble.com.