fix crash with 0 channels
fix crash with 0 channels

Motiejus/sox,jacksonh/sox,Distrotech/sox,jacksonh/sox,MageSlayer/sox,Motiejus/sox,uklauer/sox,uklauer/sox,pcqpcq/sox,MageSlayer/sox,Distrotech/sox,CaptainHayashi/sox,mhartzel/sox_personal_fork,CaptainHayashi/sox,MageSlayer/sox,jacksonh/sox,mhartzel/sox_personal_fork,Motiejus/sox,davel/sox,Motiejus/sox,davel/sox,MageSlayer/sox,uklauer/sox,pcqpcq/sox,CaptainHayashi/sox,pcqpcq/sox,mhartzel/sox_personal_fork,CaptainHayashi/sox,pcqpcq/sox,mhartzel/sox_personal_fork,Distrotech/sox,davel/sox,cbagwell/sox,cbagwell/sox,cbagwell/sox,Distrotech/sox,davel/sox,uklauer/sox,MageSlayer/sox,cbagwell/sox,jacksonh/sox