For all three types of violent crime, most of the racial disparity is due to blacks committing crimes at much higher rates. You might think this is obvious, but many liberals think the gap is due to a racist criminal justice system. Some of the difference in convictions is due to a greater black risk, given a crime, of being arrested. Some of this might be due to lower average black intelligence which leads to riskier crimes.
Finally, little or none of the racial gap is due to blacks being more likely to be convicted of a felony (which is likely to land one in prison for at least a year). In fact, given an arrest for rape, a white man is more likely to be convicted than a black man. This might be, in part, due to less willingness of African American jurors to put a fellow black behind bars for a crime that can be difficult to prove. Or perhaps victims of black offenders--often black themselves--tend to be less reliable.
Overall, if liberals are bothered by the racial disparity in prison (myself, I care about punishing bad guys), the data suggests that they should focus on black criminality, not the system.