if( trk_h < bd_height ) trk_h = bd_height;
for( Track *vtrk=tracks->first; vtrk; vtrk=vtrk->next ) {
if( vtrk->data_type != TRACK_VIDEO ) continue;
if( trk_h < bd_height ) trk_h = bd_height;
for( Track *vtrk=tracks->first; vtrk; vtrk=vtrk->next ) {
if( vtrk->data_type != TRACK_VIDEO ) continue;