Fix regression in multiple audio tracks.
Fix regression in multiple audio tracks.

Regresssion introduced with audiochannels normalization filter.

zzhhui/mlt,gmarco/mlt-orig,xzhavilla/mlt,ttill/MLT,siddharudh/mlt,gmarco/mlt-orig,siddharudh/mlt,mltframework/mlt,xzhavilla/mlt,zzhhui/mlt,anba8005/mlt,siddharudh/mlt,siddharudh/mlt,anba8005/mlt,j-b-m/mlt,j-b-m/mlt,siddharudh/mlt,wideioltd/mlt,mltframework/mlt,ttill/MLT,xzhavilla/mlt,ttill/MLT,anba8005/mlt,zzhhui/mlt,mltframework/mlt,anba8005/mlt,wideioltd/mlt,zzhhui/mlt,ttill/MLT,xzhavilla/mlt,xzhavilla/mlt,gmarco/mlt-orig,anba8005/mlt,siddharudh/mlt,j-b-m/mlt,wideioltd/mlt,anba8005/mlt,zzhhui/mlt,ttill/MLT,anba8005/mlt,xzhavilla/mlt,gmarco/mlt-orig,anba8005/mlt,siddharudh/mlt,ttill/MLT,j-b-m/mlt,j-b-m/mlt,mltframework/mlt,gmarco/mlt-orig,ttill/MLT,j-b-m/mlt,xzhavilla/mlt,gmarco/mlt-orig,j-b-m/mlt,gmarco/mlt-orig,wideioltd/mlt,mltframework/mlt,mltframework/mlt,zzhhui/mlt,ttill/MLT,wideioltd/mlt,gmarco/mlt-orig,wideioltd/mlt,xzhavilla/mlt,mltframework/mlt,gmarco/mlt-orig,siddharudh/mlt,siddharudh/mlt,xzhavilla/mlt,ttill/MLT,zzhhui/mlt,zzhhui/mlt,mltframework/mlt,anba8005/mlt,mltframework/mlt,wideioltd/mlt,j-b-m/mlt,zzhhui/mlt,wideioltd/mlt,j-b-m/mlt,wideioltd/mlt,mltframework/mlt,j-b-m/mlt