yading@11: testsrc=r=5:n=1:d=2 [v1];
yading@11: sine=440:b=2:d=1    [a1];
yading@11: testsrc=r=5:n=1:d=1 [v2];
yading@11: sine=622:b=2:d=2    [a2];
yading@11: testsrc=r=5:n=1:d=1 [v3];
yading@11: sine=880:b=2:d=1    [a3];
yading@11: 
yading@11: [v1][a1][v2][a2][v3][a3] concat=v=1:a=1:n=3