type = av_hwdevice_find_type_by_name(hw_dev);
if( type == AV_HWDEVICE_TYPE_NONE ) {
fprintf(stderr, "Device type %s is not supported.\n", hw_dev);
type = av_hwdevice_find_type_by_name(hw_dev);
if( type == AV_HWDEVICE_TYPE_NONE ) {
fprintf(stderr, "Device type %s is not supported.\n", hw_dev);