In version 3.0.0 this command worked fine as a postbuild step:
arm-none-eabi-objcopy -O srec "myprog.elf" "myprog.srec"
& C:\Users\hp\Documents\"Visual Studio 2013"\Projects\encode\Debug\encode "myprog.srec" "myprog.hex"
But when I converted it to 3.2 I had to add an & AND move the quotes in the directory in order to get it to work without an unterminated quote syntax error message:
arm-none-eabi-objcopy -O srec "myprog.elf" "myprog.srec"
&& C:"\Users\hp\Documents\Visual Studio 2013\Projects\encode\Debug\encode" "myprog.srec" "myprog.hex"